NEIMME Transactions
Volume 3
NORTH OF ENGLAND INSTITUTE OF MINING ENGINEERS.
TRANSACTIONS.
VOL. 3.
1854 & 1855.
LONDON: JOHN WEALE; NEWCASTLE-ON-TYNE: ANDREW REID, 40, PILGRIM
STREET.
1855.
INDEX TO VOL. III.
A
Air-ways, J. J. Atkinson on................................ 185
Analysis of Rocks, by H. Taylor, Esq......................... 14
Anthracite, Analysis of.................................... 23
Airey, Professor, his Letter to Mr. Anderson.................. 68
Anatolia, Coal in........................................ 61
Atkinson, J. J., on the Theory of Mine Ventilation.............. 73
B Blowers, Practice with Gas at............................. 33
C
Coke, Analysis of Morrison's Patent.......................... 23
Cleveland Iron-stone, Analysis of............................ 24
College of Mining Science.................................. 57
Conveyance of Coal Underground, N. Wood on...............'. 239
Coal found in Roumelia and Anatolia..............A........ 61
D Division of Air Currents ..................................129
B
Elastic Power of Aqueous Vapour .......................... 180
Elemore Colliery, Experiments at............................252
Friction of Tubs Conveying Coal............................ 251
G Gas at Blowers, Practice with.............................. 33
(iv)
Gas Discharged through Pipes.............................. 217
Greenwell on Mine Engineering- ............................ 229
Gas at Blowers, Conversation on............................ 230
H
Hobberlaw Limestone, Analysis of .......................... 24
Holy Island Limestone, Analysis of.......................... 24
Horses Underground »..................................... 267
I
Iron-stone of Cleveland, Analysis of.......................... 24
K
Killingworth Colliery, Experiments at........................ 253
L
Longridge, II. G., on Turkish Coal Formations................ 61
Lanarkshire, Section of Coal Measures in...................... 235
M
Mine Ventilation, Atkinson on ..............,............... 73
Motive Power on Railways Underground...................... 200
P
Playfair on Turkish Coal .................................. 69
Practical Ventilation.........................•>............ 148
Pressure Guages......................................... 148
Pontop Colliery, Experiments at............................ 254
R
Reid, P. S., on Practice with Gas at Blowers.................. 33
Roumelia, Coal in........................................ 61
Rocks, Analysis of, by Mr. H. Taylor........................ 14
Railways Underground, Motive Power on .................... 200
S
Shotton Coal, Analysis of.................................. 23
Sinclair, Mr,, Experiments by .............................. 259
T
Taylor, H., his Analysis of Rocks .......................... 14
Turkey, Coal Found in ............,....................... 69
(v)
U Undergound, Conveyance of Coal............................239
V \
Ventilation, Theory of, by J. J. Atkinson .................... 73
Ventilation of Mines, Supplementary Matter to a Paper on the
Theory of, by Mr. J. J. Atkinson......................321
Ventilation of Mines, Notes on Mr. J. J. Atkinson's Paper on the
Theory of, by Mr. T. J. Taylor........................ 341
Ventilating Furnaces, Fuel Consumed by ....................100
Ventilation, Currents of Divided ............................129
Vapour, Aqueous, Elastic Force of..........................180
w
Wood, Nicholas, on the Conveyance of Coal Underground ......239
ADVERTISEMENT.
The Institution is not, as a body, responsible for the facts and
opinions advanced in the following Papers read, and in the Abstracts of
the Conversations which occurred at the Meetings during the Session.
taunt %tpxl, ku
In presenting their Annual Report, the Council have to congratulate the
meeting on the close of the third successful year of the establishment
of the Institute- There are now comprised in the roll of its members the
names of gentlemen resident not only in Northumberland and Durham, but
also in Yorkshire, Lancashire, Derbyshire, Staffordshire, Warwickshire,
Somerset, Monmouthshire, Cumberland, Gloucestershire, Shropshire, and
North and South Wales, so that the Institute represents in its own body
all the principal mining districts of England and Wales. Thus has been
already accomplished one of the leading and most important objects which
called the Society into existence, that of establishing a communication
between the several mining districts, and enabling each to acquaint
itself with the peculiar, and in some cases superior, practice of the
others. The meeting will probably agree with the Council that from the
new species of circulation thus produced of the mining knowledge and
talent of the country, the most valuable consequences may be expected to
result. It is to the Institute that the initiation of a design so
comprehensive is due; and a firm hope may be expressed that the
Institute will continue to be the persevering and successful medium of
perpetuating its own good work.
During the past year the Society, besides numerous verbal discussions on
various topics, have had papers and documents read or communicated on
the following subjects.
Analysis of the Strata of the Coal Formation, by II. Taylor, Esq.,
communicated by Thomas John Taylor, Esq.
Account of the Coal Formations of Erekli and Radosto, with Specimens, by
H. G. Longridge, Esq.
(viii)
The Theory of the Ventilation of Mines, by J. J. Atkinson, Esq.
On Practice of Gas at Blowers, by P. S. Eeid, Esq.
Analysis of the Specimens of Coal accompanying Mr. H. G. Long-ridge's
Paper, by Dr. Richardson.
Communications from Messrs. Grant on the subject of their Patent Safety
Cages.
On the Conveyance of Coals Underground, by N. Wood, Esq., President of
the Institute.
Abstract of Mr. T. Y. Hall's list of Pits in the Great Northern Coal
Field.
A Vertical Section of the Coal Measures of Lanarkshire, presented by
Ralph Moore, Esq.
Several Volumes of the Mining Journal, presented by William Anderson,
Esq.
A Practical Treatise on Mining Engineering, presented by the Author,
George C. Greenwell, Esq.
The Council recommend to the Institute the adoption of a more systematic
method of reciprocating with other Scientific Institutions. The three
Volumes of Transactions which will shortly be published, contain, it may
fairly be affirmed, a mass of information well worthy of the notice of
such Institutions, and, therefore, entitling the Society to expect an
interchange. On this ground the Council advise that communications be
addressed to the leading National and Continental Scientific Bodies
offering to exchange publications. To a certain extent this has been
already done; but not in the most effective manner, rior indeed, with
the same inducements that the improved position of the Society enables
it now to offer.
The Council also advise the extension of the Library of the Institute,
now that rooms are prepared for its reception: and would draw attention
to the resolution enabling Members to recommend books or documents to be
purchased, if approved by the Council: a privilege which, it is hoped,
will be more extensively used by individual Members. The Council may
here mention that an opportunity is now afforded of securing a
collection of the fossils of the coal formation, which is the more
valuable as being the one that furnished the illustrations to "Lindley
and Hut-ton's Fossil Flora." As this subject will be discussed in the
meeting subsequently to the reading of the Report; the Council content
themselves at present with drawing attention to the subject; and with
expressing a hope, that this collection will not be permitted to quit
the district to
(ix)
which it so properly belongs, and which, they understand, is likely to
be its fate, unless the Society interfere to prevent it.
The project of the establishment of a College of Mining and
Manufacturing Science has been already before this society. It was also
brought before the Coal Trade of these districts generally, by the
diffusion of the Report read on the occasion of the last anniversary,
and received the unanimous and cordial approbation of the trade at a
general meeting. It was, however, of course, one of the conclusions to
which the Council came, on considering the subject, that such an
establishment, to be successful, must be of an enlarged and even
national character. And as a delegation, representing the Coal Mining
interests of the kingdom at large, assembled in London, in the course of
the summer just passed, it was deemed a favourable opportunity for
bringing the subject before that meeting, with a view to obtain their
concurrence in the proposed measure. This was done, accordingly; and the
subject was brought before the delegates, together with such Members of
Parliament as happened to be present, by the gentlemen representing, on
that occasion, the Coal Mining interests of this district.
The gentlemen present from various parts of England, connected with the
Coal and Iron Mining interests, were quite alive to the strength of the
motives for founding, if possible, such an institution upon a broad and
firm foundation; and in accordance with this feeling', a resolution was
unanimously agreed to, expressive of their concurrence in the proposed
design. A committee was also appointed, composed of gentlemen
representing the Mining interests, to whom the duty was allotted of
making the project known in the several districts, and again meeting for
the purpose of discussing and agreeing upon the necessary details, and
of embodying the plan, so matured, in the shape of a Prospectus, to be
submitted to the Mining and Manufacturing interests of Great Britain.
Such is the position which a project, originated by this Society, and
fostered by the approval of the Coal Trade of Northumberland and Durham,
has taken.
For the Financial position and prospects of the Society the Council
refer to the Report of the Finance Committee, and recommend the adoption
of the measures which have been already adverted to, as being calculated
to add to the funds of the Society, and thus to increase its means of
utility.
The Council especially recommend that application be made to the owners
of those collieries whose subscriptions have not yet been received.
h '
00
In conclusion, the Council cannot but congratulate the Society at the
close of this third year of the Institution upon the progress made by
it— a progress which has extended the ramifications of the Society
throughout the entire Coal Mining districts of England and Wales. Of the
purposes which led to its establishment none have been lost sight of,
and all have been more or less realized.
An increase of 21 members has taken place during the past year; the
total number of ordinary members being now 159, and of honorary members,
English and Foreign, 13.
August 2nd, 1855,
fmmn Cnmmittej's %t$ml
31ST JULY, 1855.
TO THE MEMBERS OF THE NORTHERN INSTITUTE OF MINING ENGINEERS. Gentlemen,
We have much pleasure in bringing the results of the third year of the
Society's operations to your notice.
It appears from the Treasurer's accounts that the cash outlay for the
year ending July 31,1855, amounts to £292 17s. 5d., and the income from
various sources to £616 15s. 3d., leaving an amount in the hands of the
Treasurer of £323 17s. lOd.
The liabilities, as per annexed balance sheet and general statement,
would appear to amount to £58 19s. 0d., and the assets of various kinds
to be of value £557 5s. 10d., leaving a balance in favour of the future
of £498 6s. lOd.
We should recommend (with the view of securing the Society's property
against risk of loss by fire), that such a sum be fixed upon as the
probable value of its property each year, in the premises which are
granted by the Coal Trade, which insurance must keep pace with the
position of the Institute, as will eiFectually maintain it from loss
such as it narrowly escaped during the past year.
We think, also, that the Minutes of the Council, with regard to the
Collection of Books, should be acted upon without delay, as so few
standard works upon mining are yet on the shelves of the Library.
We should also advise the publications of the Society to be more freely
advertised, with view of the timely realization of assets, so as not to
accumulate these matters to too great an extent.
Probably a Sub-committee, to include the Treasurer and several members
of the Council, to be called the Library Committee, two of which
(xii)
Should be empowered to act, would be the best way of attaining this
result. And we would advise that the whole care of the Society's Papers,
with that of collecting- fresh works of interest, Models, Specimens, &c,
&c, be given to the Committee, provided that its appointment should be
approved of.
Concluding' with the observation that publicity is the great secret of
success to an institution such as yours, we should recommend every
exertion to be used in making known its objects, not only with regard to
the increase of its members, but also with the view of securing the
co-operation of Coal Owners from distant parts, who, both as regards the
true interest of their collieries and the welfare of their workmen, are
certain to become supporters of your society, when its wants and objects
are more fully known and appreciated.
We believe that wherever the Institution has been spoken of, both in
this country and abroad, the opinion of its efforts and aims has excited
much interest, which has been unanimous in its favour.
Leaving the further elucidation of the Society's position to the able
Report of the Council,
We are, Gentlemen,
Your obedient servants,
WILLIAM BARKUS,
P. S. REID,
EDW. F. BOYD, Treasurer.
(xiii)
^ o? o coo ooooo oco
Ph oi p-i 00 CO O . O O (M fH OJ
IN. 10
P rl
rH
rH rH
S ,', "^ W OTH OiOCQrHO
COCO
£5 MM rH Ci C3 « C!
\ (M
rH
r-4 r-i
\
CO CD
<-< S d ^ • 00 r«i • • .
f-i ;j-< \
£ ^ ^ -d ^ ^ ^ ^^ £ pi, -o \•
TB
Kj' I njOSOS 03 Oj
OS OS Cu C3
p . cq-~ - - «. 5 a »-
5 '«? I.
ud ^ -h
tT o co
0 GO ^
H £_____________________________ _ ___
Ph "ZT"aJ © ©
O CO CO"
i_4 i • «& <0 CO
O IN.
to
Xj ,.-, CO CS IN.
CO no
CO
rH Hi O IN O}
CO r-l ¦—I
O c^ c\*
co
^ • O . fe • 6fl
-d •
Hi ; „ • j 'f OOOOOOOO
C8 .
^ S 3 • r£ • ^ rH
§ .
pq c_(- ¦• «• s.v^x.x.i:x.x.
f3^
h «? I a -
(xiv)
..Oooooooo ®
1° M ~ m «* o
1Q
. rw © 2 •* Q * S
• . £» • : » . be . g ?. § ; g :
h #2 '. • '3 • ^ • -P4 • -a : .SP •
° • : ^ a £ 3 • ,3 • J§ • £ :
1 :-1 :11 !• I " : 1 '• * 5
-S •- 12 p- -g -H, p ^ p 8 pi o -J 6<
F—i PJhPs^dEiPJo2rOi-^o,~ic!Ci3
5| ¦& * * * * * * s
H I
n ion H 22 ±*
^ s
== •
0 ©
< . o • © ° M
•J . aa r-1
00 N
p « H H co
** q*
i »v • ^ ?-< p. \
^*
P5 -+-> ,2 .2 -3 o . \
jc
us (§ rt .a & -a ^ s \ «!
,-J tM JO t... e- e*H P
\
^. 'S ^ ^ - ,rt \ p
p £ p g § S -g \ - ¦ 3
•9 -9 «« \g
iO CO
His Grace the Duke of Northumberland.
The Right Honourable the Earl of Lonsdale,
The Right Honourable the Earl Grey.
The Right Honourable the Earl of Durham.
The Right Honourable Lord Wharncliffe.
The Right Honourable Lord Kavensworth.
The Right Reverend the Lord Bishop of Durham.
The Very Reverend the Dean and Chapter of Durham.
The Venerable Archdeacon Thorpe, the Warden of Durham
University. Wentworth B. Beaumont, Esq.
|>raikttt
NICHOLAS WOOD, Hetton Hall, Fence Houses.
WM. ANDERSON, St. Hilda's Colliery, South Shields.
ED W. POTTER, Cramlington Colliery, Newcastle.
T. J. TAYLOR, Earsdon, Northumberland.
R. STEPHENSON, M.P., 24, Great George Street, Westminster.
Cmraril
W. ARMSTRONG, Wing-ate Grange, Ferry Hill.
GEO. ELLIOT, Houghton-le-Spring, Fence Houses.
J. A. LONGRIDGE, Quayside, Newcastle.
P. S. REID, Pelton Colliery, Chester-le-Street, Fence Houses.
W. BARKUS, Sen., Gateshead Low Fell, Gateshead.
G. C. GREEN WELL, Radstock Colliery, near Bath.
J. TAYLOR, Haswell Colliery, near Durham.
T. W. JOBBING, St. Mary's Terrace, Newcastle.
C. CARR, Seghill Colliery, Newcastle.
M. LIDDELL, Benton Grange, near Newcastle.
J. ROBSON, North Bailey, Durham.
J. EASTON, Hebhurn Colliery, Gateshead.
€mmm.
E. F. BOYD, Urpefrh Colliery, Chester-le-Street, Fence Houses. THOMAS
DOUBLEDAY.
Edward Shipperdson, Esq., South Bailey, Durham.
Goldsworthy Gurney, Esq., Bude Castle, Cornwall.
Charles Morton, Esq., Mining- Inspector, Wakefield.
Joseph Dickinson, Esq., Mining Inspector, Barr Hill Cottage, Pendleton,
Manchester. Herbert Mackworth, Esq., Mining Inspector, Clifton Wood
House, Bristol. Thomas Wynne, Esq., Mining Inspector, Longton, North
Staffordshire. Matthias Dunn, Esq., Mining Inspector, Newcastle. De Von
Decken, Berghauphnan, Bonn, Prussia. Baron Von Humbolt, Potsdam,
Prussia. Mons. De Vaux, Inspector-General of Mines, Brussels.
Geheimerbergrath Von Carnell, Berlin. Mons. Gonot, Mons., Belguim. Mons.
de Boureialle, Paris.
1 Anderson, W., St. Hilda's Colliery, South Shields.
2 Anderson, C. W., St. Hilda's Colliery, South Shields.
3 Arkley, G. W., Harton Colliery, South Shields.
4 Atkinson, J. J., Pontop, Gateshead.
5 Atkinson, J., Coleford, Gloucestershire.
6 Adams, W., Ebw Vale "Works, Newport, Monmouthshire.
7 Arkless, B., Tantoby, Gateshead.
8 Ashworth, —, Poynton, Cheshire.
9 Armstrong-, W., Wingate Grange, Ferry Hill.
10 Barrass, T., Little Chilton Colliery.
11 Boyd, E. F., Urpeth, Chester-le-Street.
12 Barkus, W., Low Fell, Gateshead.
13 Barkus, W., Jun., Team Colliery, Gateshead.
14 Bell, J. G., 1, Higham Place, Newcastle.
15 Barkley, J. T., Constantinople.
16 Berkley, C, Marley Hill Colliery, Gateshead.
17 Bolckow, H. W. F., Middleshro', near Stockton.
18 Brown, J., 6, North Parade, Derby.
19 Bourne, S., Monkwearmouth Colliery, Sunderland.
20 Bourne, P., Whitehaven, Cumberland.
21 Burn, D., Busy Cottage Iron Works, Newcastle.
22 Bell, W. H., Sacriston Colliery, Chester-le-Street, Fence Houses.
23 Bell, C. W., 1, Gresham Place, Newcastle. 21 Bell, T., Cassop
Colliery, Durham.
25 Bell, J. T. W., Higham Place, Newcastle.
26 Bell, I. L., Washington, Gateshead.
27 Booth, P., Evenwood Colliery, Bishop Auckland.
(xix)
28 Bartholomew, C, Rotherham, Yorkshire.
29 Beacher, E., Grange Colliery, Wakefield, Yorkshire.
30 Baker, J. P., Chillingworth Colliery, Wolverhampton.
31 Binns, C, Claycross, Derbyshire.
32 Bassett, A., Tredegar Mineral Estate Office, Cardiff.
33 Cadwallader, R., Ruabon Colliery, Wrexham.
34 Clark, G., Wallsend Colliery, Newcastle.
35 Croudace, J., Washington Colliery, Gateshead.
36 Croudace, C, Washington, Gateshead.
37 Crawford, T., Bowes House, Fence Houses.
38 Crawford, T., Jun., Little Town Colliery, Durham.
39 Crone, S. C, Little Town Colliery, Durham.
40 Carr, C, Seghill Colliery, Newcastle.
41 Coulson, W., Crossgate Foundry, Durham.
42 Charlton, G., Chesterton, Newcastle-under-Lyne, Staffordshire.
43 Carnes, J., West Hetton, Ferry Hill.
44 Cope, J., King Swinford, near Dudley.
45 Cordner, R., Crawley Side, Stanhope, Wearclale.
46 Cowen, J., Blaydon Burn, near Newcastle.
47 Dixon, R., Claypath, Durham.
48 Dobson, S., Cardiff, Glamorganshire.
49 Douglas, T., Bedford Lodge, Bishop Auckland.
50 Daglish, J., Seaton Colliery, Fence Houses.
51 Davidson, J., Church-street, Durham.
52 Day, J. W., Pelaw, Chester-le-Street, Fence Houses.
53 Dumolo, J., Danton House, Coleshill, Warwickshire.
54 Elliot, G., Houghton-le-Spring, Fence Houses.
55 Elliott, W., Etherley Colliery, by Darlington.
56 Easton, J., Hebburn Colliery, Gateshead.
57 Evans, J., Dowlais Iron Works, Merthyr Tydvil, South Wales.
58 Errington, C. E., Westminster.
59 Foord, J. B., Secretary-General of Mining Association, 52, Broad-
street, London.
60 Forster, J. H., Old Elvet, Durham.
61 Greenwell, G. C, Radstock Colliery, near Bath.
62 Gray, J., Garesfield Colliery, Newcastle.
63 Green, G., Rainton Colliery, Fence Houses.
64 Greene, W., Jun., Framwellgate Colliery, Durham.
65 Hall, T. Y., Eldon-square, Newcastle.
(xx)
66 Heckels, R., Bunker's Hill, Fence Houses.
67 Hedley, J., Waterloo Road, Burslem.
68 Hawthorn, R., Engineer, Newcastle.
69 Hawthorn, W., Engineer, Newcastle.
70 Harrison, T. E., Engineer, Westoe, South Shields.
71 Haggie, P., West-street, Gateshead.
72 Hann, W., Hetton, Fence Houses.
73 Higson, P., Manchester, Lancashire.
74 Holt, J., Stanton Iron Works, Derby.
75 Hunter, W., Quayside, Newcastle.
76 Hunter, S., Tredegar Iron Works, Newport, Wales.
77 Hynde, W., Ruabon Iron Works, Wrexham.
78 Johnson, R. S., West Hetton, Ferry Hill.
79 Johnson, J., Willington Colliery, Newcastle.
80 Johnson, G., Laffak Colliery, St. Helen's, Lancashire.
81 Joicey, J., Quayside, Newcastle.
82 Joicey, J., Tanfield Lea, Durham.
83 Jones, E., Lilleshall Iron Works, Shiffnal, Salop
84 Jobling, T. W., St. Mary's Terrace, Newcastle.
85 Kimpster, W., Washington Office, Quayside, Newcastle..
86 Laws, J., Prudhoe Castle, Northumberland.
87 Liddell, J. R., Killingworth Colliery, Newcastle.
88 Liddell, M., Benton Grange.
89 Longridge, J., Quayside, Newcastle.
90 Longridge, H. G., Barrington Colliery, Newcastle.
91 Locke, Jos., M.P., Westminster.
92 Morton, H., Lambton Office, Fence Houses.
93 Morton, H. T., Lambton Office, Fence Houses.
94 Murray, T., Chester-le-Street, Fence Houses.
95 Marley, J., Bishop Auckland.
96 Mundle, W., Ryton, Gateshead.
97 Middlqton, J., Davison's Hartley Office, Quayside, Newcastle.
98 Mercer, J., St. Helen's, Lancashire.
99 Muleaster, H., High Street, Maryport, Cumberland.
100 MacLean, J. C.
101 Maynard, T. C, North Bailey, Durham.
102 Potter, E., Cramlington Colliery, Newcastle.
103 Potter, W. A., Cramlington Colliery, Newcastle.
104 Palmer, A. S., Seaton Burn Colliery, Newcastle.
(xxi)
105 Palmer, C. M., Quayside, Newcastle.
106 Palmer, J. B., Jarrow, South Shields.
107 Philipson, R. H., Cassop Colliery, Durham.
108 Peace, W., Hague Cottage, Wigan, Lancashire.
109 Plummer, B., 4, Queen's-square, Newcastle.
110 Richardson, Dr., Portland Place, Newcastle.
111 Robson, J., North Bailey, Durham.
112 Robson, J. G., Byer's Green Colliery, Durham.
113 Robson, M. B., Field House, Borough Road, Sunderland.
114 Reed, R. G., Cowpen Colliery, Northumberland.
115 Reid, P. S,, Pelton Colliery, Chester-le-Street, Fence Houses.
116 Rutherford, J., Shincliffe Colliery, Durham.
117 Ramsay, J., Whickham, Gateshead.
118 Southern, G. W., Springwell Colliery, Gateshead.
119 Southern, J. M., Springwell Colliery, Gateshead.
120 Stobart, W., Roker, Sunderland.
121 Stobart, H. S., Etherley, by Darlington.
122 Simpson, R., Ryton, Gateshead.
123 Simpson, L., Medomsley Colliery, Durham.
124 Spencer, W., jun., Woodifield Colliery, Crook, by Darlington.
125 Storey, T., St. Helen's Auckland, Bishop Auckland.
126 Stannier, F., Manor House, near Stoke-upon-Trent, Staffordshire.
127 Smith, J., Thoniley Colliery, Durham.
128 Smith, F., Bridgewater Canal Office, Manchester.
129 Seymour, M., South Wingate, Ferry Hill.
130 Stephenson, R., M.P., 24, George Street, Westminster.
131 Sanderson, R. B., jun., West Jesmond, Newcastle.
132 Sopwith, T., Allenheads, Haydon Bridge.
133 Stott, R., Ferry Hill.
134 Stenson, W., Whitwick Colliery, Ashby-de-la-Zouch.
135 Stenson, W., jun., Whitwick Colliery, Ashby-de-la-Zouch.
136 Sinclair, E., Tredegar, Newport, Monmouthshire.
137 Straker, J., South Shields.
138 Taylor, H., Earsdon, Northumberland.
139 Taylor, T. J., Earsdon, Northumberland.
140 Taylor, J., Haswell Colliery, Durham.
141 Telford, W., Cramlington, Newcastle.
142 Todd, H. W., Mickley Colliery, Newcastle,
143 Thomas, W., Bogilt, Holywell, Flintshire.
(xxii)
144 Thompson, T. C, Kirkhouse, Brampton, Cumberland.
145 Trotter, J., Newnam, Gloucestershire.
146 Vaughan, J., Middlesbro', near Stockton.
147 Ware, W. H., The Ashes, Stanhope, Weardale.
148 Walker, J., Lakelock, Wakefield, Yorkshire.
149 Wales, T., Dowlais Iron Works, Merthyr Tydvil, Wales.
150 Wood, N., Hetton Hall, Fence Houses.
151 Wood, C. L., Blackhoy Colliery, Bishop Auckland.
152 Wood, W., Trimdon, Trimdon Colliery, Hartlepool.
153 Wales, J., Hetton Colliery, Fence Houses.
154 Watson, W., High Bridge, Newcastle.
155 Wilson, J. B., Haydock Rope Works, near Warrington, Lancashire.
156 Woodhouse, J. T., Midland Road, Derby.
157 Walker, T. jun., High Street, Maryport.
158 Watney, A., Gwendraeth, Iron Works, Carmarthenshire.
159 Witham, Rev. Thos., Lartington Hall, Barnard Castle.
1.—That the Members of this Society shall consist of Ordinary Members,
Life Members, and Honorary Members.
2.—That the Annual Subscription of each Ordinary Member shall be £2 2s.
0d., payable in advance, and that the same shall be considered as due
and payable on the first Saturday of August in each year.
3.—That all persons who shall at one time make a Donation of £20 or
upwards, shall be Life Members.
4.—Honorary Members shall be persons who shall have distinguished
themselves by their Literary or Scientific attainments, or made
important communications to the Society.
5.—That a General Meeting of the Society shall be held on the first
Thursday of every month, at 1 o'clock p.m., and the General Meeting in
the month of August shall be the Annual Meeting, at which a report of
the proceedings, and an abstract of the accounts of the previous year,
shall be presented by the Council. A Special Meeting of the Society may
be called whenever the Council shall think fit, and also on a
requisition to the Council, signed by ten or more Members.
6.—No alteration shall be made in any of the Laws, Rules, or Regulations
of the Society, except at the Annual General Meeting, or at a Special
Meeting; and the particulars of every alteration to be then proposed
shall be announced at a previous General Meeting, and inserted in its
minutes, and shall be exhibited in the Society's meeting-room 14 days
previously to such General Annual or Special Meeting.
7.—Every question which shall come before any Meeting of the Society
shall be decided by the votes of the majority of the Ordinary and Life
Members then present and voting.
8.—Persons desirous of being admitted into the Society as Ordinary or
Life Members shall be proposed by three Ordinary or Life Members,
(xxiv) or both, at a General Meeting. The proposition shall be in
writing, and signed by the proposers, and shall state the name and
residence of the individual proposed, whose election shall be ballotted
for at the next following General Meeting, and during the interval
notice of the proposition shall be exhibited in the Society's room.
Every person proposed as an Honorary Member must be recommended by at
least five Members of the Society, and elected by ballot at the General
Meeting next succeeding. A majority of votes shall determine every
election.
9.—The Officers of the Society shall consist of a President, four
Vice-Presidents, and twelve Members who shall constitute a Council
for the direction and management of the affairs of the Society; and of
a Treasurer, and a Secretary ; all of whom shall be elected at the
Annual
Meeting, and shall be re-eligible. Lists containing the names of all
the
persons eligible having been sent by the Secretary to the respective
Members, at least a month previously to the Annual Meeting;—the
election shall take place by written lists, to be delivered by each
voter
in person to the Chairman, who shall appoint scrutineers of the lists;
and the scrutiny shall commence on the conclusion of the other business
of the meeting. At meetings of the Council, five shall be a quorum,
and the record of the Council's proceedings shall be at all times open
to
the inspection of the members of the Society.
10.—The Funds of the Society shall be deposited in the hands of the
Treasurer, and shall be disbursed by him, according to the direction
of the Council.
11.—The Council shall have power to decide on the propriety of
communicating to the Society any papers which may be received, and they
shall be at liberty, when they think it desirable to do so, to direct
that any paper read before the Society shall be printed. Intimation
shall be given at the close of each General Meeting of the subject of
the paper or papers to be read, and of the questions for discussion at
the next meeting, and notice thereof shall be affixed in the Society's
room 10 days previously. The reading of papers shall not be delayed
beyond 3 o'clock, and if the election of members or other business
should not be sooner-dispatched, the President may adjourn such business
until, after the discussion of the subject for the day.
NORTH OF ENGLAND INSTITUTE
OF
MINING ENGINEERS.
GENERAL MEETING, THURSDAY, SEPTEMBER 7th, 1854, IN THE ROOMS OF THE
INSTITUTE, WESTGATE STREET, NEWCASTLE-UPON-TYNE.
Nicholas Wood, Esq., President of the Institute, in the Chair.
Mr. Doubleday, the secretary, having read the minutes of the last
general meeting-, and also of the council,
The President said, that the first business of the meeting was the
consideration of the proceedings of the Council, and the only subject
which required any discussion was the recommendation made of having
detached copies of the proceedings of the last meeting, together with
the Report, printed separately from the volume of the proceedings of the
Institute, and circulated among the members generally, and also sent to
other parties who took an interest in the proceedings of the Institute;
he thought it a very advisable measure, and if no observations were made
on the subject, he would take a show of hands upon it. Agreed to
unanimously.
Mr. T. Y. Hall moved, and Mr. T. J. Taylor seconded the nomination of
Mr. Joseph Cowan, Blaydon Burn, as a member of the Institute.
Mr. Wynne recommended, and Mr Edward Sinclair seconded, the nomination
of Mr. Charles Jones, of Lille Hall Iron Works, and Mr. Browne, of
Oversea!, Ashby-de-la-Zouch, as members of the Institute.
The President begged to observe, for the future information of members
generally, with reference to new members being proposed, that there was
a rule applicable to that part of their proceedings, which was as
follows, Vol. III.—Sept., 1854.
b
4
that, u Persons desirous of being* admitted into the Society as ordinary
or life members, shall be proposed by three ordinary or life members, or
both, at a general meeting. The proposition shall be in writing, and
signed by the proposers, and shall state the name and residence of the
individual proposed, whose election shall be ballotted for at the next
following general meeting; and that during the interval notice of the
proposition shall be exhibited in the Society's room." Heretofore they
had no room to exhibit the names of parties proposed, but the Institute
having now got one, he thought it was necessary that the above rule
should be carried out hereafter; and that being so, they had better
begin with those gentlemen who had just been proposed. He therefore
suggested, that the names of those gentlemen be placed in their room,
and that at the next meeting their admission be subject to a ballot.
The suggestion of the President was then assented to, and in future the
names of all parties, proposed as members, will be exhibited according
to rule.
The President next remarked, that he thought it would be in the
recollection of all the members present, that at the annual meeting he
stated, owing- to the temporary indisposition of Mr. Taylor, the report
of the Council of last year's proceedings had not been drawn up. He (the
President) was glad to see Mr. Taylor among them that day, quite
recovered, and in "good spirits, with the Report which would then be
read-Mr. Doubleday, the secretary, then read the Report. The President
then moved that the Report just read be received and adopted, which was
carried unanimously.
The President, after stating that the next subject for consideration was
the Paper of Mr. T. Y. Hall, " On the Extent and Probable Duration of
the Northern Coal Field," proceeded to remark, that the Institute was
much indebted to Mr. Hall for his very elaborate Paper, which contained
a little of every subject relating to their coal field, and comprised a
selection of very useful information. He should be glad to hear any
observations on it from any gentleman present. He thought discussion a
subject of great importance, inasmuch as the Paper contained a maps of
statistical information of every locality. Ifc was therefore desirable
that a document of this description should have the most careful
consideration, so that if there appeared to be any errors in it, they
might be corrected by such discussion, which would be circulated with
the Paper itself. Looking at the wide and discursive nature of the
communication, it was not unlikely that a few inaccuracies might exist;
and, therefore, if corrected by the members acquainted with the
localities, it
5
Would render the Paper more useful. Such a course, besides being*
desirable, did not detract in any degree from the merits of the Paper.
Mr. Hall said, that when he was in Austria the Paper was in the
printer's hands, and part of which he never had the opportunity of
correcting until it was sent to him in that country. On glancing-
over the proofs he discovered a few inaccuracies, upon which he
immediately wrote to the secretary, apprising him of them, and begged
that he would lay the matter before the Council, in order that they
might be corrected. Part of the errors were connected with the coal
field, and others consisted of some figures misplaced opposite the
names of the iron works, all of which had since been corrected.
As, however, the members had got their copies, he proposed to
reprint four pages containing the corrections, which, with the
appendix, could be placed at the end of the Paper. Each member,
therefore, before he got the entire proceedings of the year bound could
easily take away the incorrect, and place the corrected pages instead of
them.
The President here gave instructions to the secretary to transmit to
every member a copy of the corrected pages; after which he proceeded to
say that there were two or three statements which, being matters of
opinion, he begged to make an observation or two upon. In the first
place, in forming a calculation of the extent of the coal field, Mr.
Hall set it forth to be 700 square miles; while Mr. Hugh Taylor made it
837 square miles; Mr. R. C. Taylor, another writer on the same subject,
makes it 780 square miles. In his opinion, he was inclined to say that
Mr. Hugh Taylor's estimate was the most correct, and that Mr, Hall's was
too low.
Mr. T. J. Taylor begged to observe, that the estimate of Mr. Hugh
Taylor, just referred to, was made about 25 years ago, and it did not
take in the portions under the sea.
The President resuming—Another point to which he would take the liberty
of adverting, was respecting the dip and rise of the strata. Mr, Hall,
in page 108, says "The coal measures slope or dip from the outcrop
towards the sea, from Widdrington Castle, on the North Coast, to Castle
Eden, near Hartlepool, in a south-easterly direction." And again, in
page 129, " As the coal measures dip towards the sea, in a southeasterly
direction from the general line of outcrop which varies in distance
proceeding for the sea westward." Prom those quotations, an impression
would be made that the strata of the coal field dipped from the westward
in a south-east direction to Hartlepool and Castle Eden; that, however,
was not a correct delineation of the position of the beds of the coal
field. The coal field of Durham and Northumberland was, in fact,
6
of a basin-like shape, cut through by the line of the coast in almost
the centre or nearer one edge of the basin. An inquirer standing with
his back to the sea at about the mouth of the harbour at Sunderland, and
looking towards Jarrow, on the Tyne, would be looking along the line of
deepest depression of the strata ; such line rising gradually from
Sunderland towards the north and west, and from every point of that line
of deepest depression the strata rises at right angles to the sea on the
one hand and to the west on the other. This line of deepest depression
is called the "swally," rising along its line to the north-west, and
dipping towards the south-east; while, along the coast to the north, and
to the south the strata rises, more rapidly to the north as being at a
greater angle from the line of deepest depression, and less towards the
south as being at a less angle therefrom; hence, along the line of coast
on each side of this line, towards the south and west on the one side,
and also towards the north and west edge of the basin on the other, the
strata gradually, but regularly, (except where disturbed by dykes or
faults) rises and crops out to the surface, or into the super-incumbent,
unconformable, magnesian limestone.
Mr. Hall—I made a similar remark in my Paper, excepting that I went a
little further south than the President. I know the seam begins to rise
south as stated, but then there must be a level from that point to
Ryhope, which I consider to be the deepest.
The President replied, that he did not find in Mr. Hall's description
any allusion to this.
Mr. Hall—Because he would find it in the Appendix. The President—The
appendix has not yet been circulated, but the deepest part of the coal
field was certainly between Monkwearmouth and By hope, and from that
point as a centre, it radiated north-west, and south from the sea-coast;
but how far the basin continued into the sea was not yet ascertained.
But the deepest known point was near Monkwearmouth. Mr. Barkus—On the
north-side of the river the coal was very fiat and appeared to be the
bottom of the basin, and probably it was, as it took its rise from that
point to the sea.
Mr. Boyd—There was a rise towards the sea from South Shields. Mr. T. J.
Taylor—A calculation had been made in the sinking at Eyhope for a rise
in that direction from Wearmouth.
The President—It was not a correct basin, as there was a " swally" from
Wearmouth, passing through Jarrow Slake until it came to the Great Dyke;
crossing which there was a continuation of the " swally/ but not quite
in the same direction.
7
Mr. T. J. Taylor supposed that that might be attributable to a local
alteration of the Dyke.
Mr. Hall—The estimate I made dipped towards Monkwearmouth.
Mr. T. J. Taylor thought the deepest point was not at Monkwearmouth, but
further east.
Mr. Hall—That is exactly my view of the subject.
The President—Certainly, but every part of Ryhope was at a less depth
than Monkwearmouth.
Mr. Hall—But Mr. Taylor and Mr Forster thought different, as well as
himself.
The President certainly was sorry to differ from three gentlemen of such
acknowledged talents. All that he felt anxious about was that the
most correctly ascertained facts should go forth in the proceedings of
the Institute. He was quite sure that such an interchange of opinions
would not detract from the merits of Mr. Hall's Paper; they might be the
means of making it more accurate and useful. Another point to which
he would next allude was with reference to the Dykes, which, on the map,
were generally extremely correct, but there were some little
inaccuracies. With respect to the Butterknowle Dyke, the Gordon
Colliery was on the north-side of it, while the plan showed it as on
the south-side. Also, as regards Westerton Colliery, which was about
2C0 yards south of the Dyke, while on the plan it was about the same
distance north of it. Such inaccuracies, upon the whole, were not
numerous, but it was desirable they should be pointed out. In looking
over the map, another matter also took his attention, which was the
distribution of the districts into different descriptions of coal, an
object of great importance, as it would tend to convey information to
parties at a distance, but this the map failed to give. He perceived
that the household coals of the Tyne were laid down as existing only on
the north-side of the Great Dyke, while on the south-side (designated
No. 4), and where household coals had existed in the greatest
perfection, Mr. Hall had omitted to colour that as household coal. He
alluded particularly to the Wallsend district.
Mr. Hall replied, that he considered it of no use shading- that part of
the Map, as all the household coals at the best seams at Wallsend and
other collieries connected with that portion of the coal field had been
worked off.
The President, however, thought it ought not to be allowed to go abroad
that the famous Wallsend district had been neglected. Again,
8
he also thought that it would have been better to have enumerated and
distinguished the characteristics of the coal field by seams rather than
by the different qualities of the coal. Take the Hut ton seam
for instance. In the southern part of the coal field the Hutton seam
was the best household coal, as at Hetton; Haswell, Stewart's, &c.
Proceeding-northward until they came to the north side of the Wear, it
became the best gas coal as at Springwell, Heworth, Usworth, &c.
Further north it became the best steam coal, as at Cramlington, Seghill,
Cowpen, &c. From thence at right angles they might pursue their
examination into the coking district, as at Marley Hill, where it
became a coking coal, in each of which places it was famous for the
particular quality of the particular locality, but in no one locality
did it partake of all the different qualities-Then the High Main seam
never varied in quality, wherever it was found its quality was a
household coal, from Earsdon at the extreme north. Southwards to
Wallsend, Hebburn, and to the Wear, still its character was the same.
Then the same was the case with the Bensham seam, as at Harton and
Hilda and southward all the way from Monkwear-mouth to Byhope and
Seaham; so that although the household coals were coloured on the map
as confined to the north-side of the Great Dyke, yet in reality they
extended from Earsdon on the north into the Seaton and extreme southern
district, throughout the whole extent of the coal field, so that if
some explanation had not been given an erroneous impression
would be produced by parties supposing that the household coals were
limited to the colours on the plan. The same remarks might apply to
the coking district. There was a seam at Thorn-ley colliery, in the
Hartlepool district, which was used as a coking coal, called the "
Harvey Seam." The same seam exists at Whitworth and Byer's Green, and
on the Tees, while the name was given to this seam on the Tyne where it
was also a coking coal. This quality of coal could, therefore,
scarcely be said to exist in any particular district, as it seemed to
extend through districts where both gas and household coals existed. He,
therefore, was inclined to think that it would have been better if the
separate seams had been delineated rather than the divisions into the
different qualities adopted on the plan. He trusted that some member
of the Institute would be induced to furnish the society with a series
of maps coloured in seams, in the manner described.
Mr. T. J. Taylor thought such a plan could not be given unless one plan
was devoted to each seam or bed of Coal.
The President again remarked how much the Institution was indebted to
Mr. Hall, as he had laid the foundation of an attempt to delineate
9
the different descriptions of coal in the coal field, but which were too
numerous to be sketched clearly and distinctly on one plan.
Mr. Hall begged to say that instead of the various plans for the
different seams, he was preparing sections similar to what was alluded
to in chap. XIV, to enable him to complete a model of the north coal
field. The Appendix, then in the printer's hand, would give a further
description, with the numerous levels of stations and pits; and thus,
with what they already proposed, together with the government levels, a
model might be made pretty complete. Nothing else but a model could
describe the coal field.
Mr. T. J. Taylor here introduced a stranger from the West Riding of
Yorkshire, whom he thought would offer a few remarks on the present
subject.—The gentleman's name is Mr. Hartop.
Mr. Hartop then rose, and addressed the meeting.—He observed that as Mr.
Taylor had alluded to him as a stranger, and also perceiving the great
interest taken in the subject alluded to by the President and others,
perhaps a few observations from him might tend to throw some light on
the subject. If he were allowed to refer to the Yorkshire coal field,
he flattered himself that he could clearly show that they were in a
similar condition to their own district. He read a Paper twelve years
ago which tended to remove the idea that coals lay in basins in large
quantities: for it so happened that he had the direct management of
various coal and iron mines in Derbyshire and Yorkshire, up to the
mag-nesian limestone above Leeds. He therefore was conversant with
that entire district, and could show then the advantages of tracing coal
and ironstone by the water level, particularly in the mountainous
districts. Mr. Hartop then entered at some length into an explanation of
the results of tracing the water levels in Yorkshire, but as he
illustrated his observations by occasional diagrams formed hastily on
the table, it was impossible to give his remarks consecutively. He
however was understood to attempt to prove that the Yorkshire coal field
was not a basin but that it was a continuous coal field, extending
itself northwards until it connected itself with the Great Northern Coal
Field of Durham.
The President, as well as Mr. Taylor, doubted the position of Mr. Hartop
as being able to form a continuous connection between the two coal
fields, but if he could prove it they would be very glad to have a paper
on the subject from him, which would be highly acceptable to the
Institute. The President then observed that they were much indebted to
Mr. Hartop for his remarks, and hoped that he would be induced to favour
the Institute with a paper on the Yorkshire coal field.
10
Mr. Hartop liad already published a paper on the subject, which was in
the Yorkshire Geological Society.
The President called attention to the paper of Mr. Hedley, but as that
gentleman was not present he thought it advisable to postpone the
discussion upon it. Any remarks on Mr. Greenwell's paper he supposed
also, must be postponed for the same reason.
Mr. T. J. Taylor then read the following paper " On the Analysis of
Rocks," by Hugh Taylor, Esq., Cramlington.
The meeting then adjourned until the first Thursday in October.
1]
ANALYSES OP EOCKS
OF THE
COAL FORMATION
BY HUGH TAYLOR, Esq., CRAMLINGTON.
COMMUNICATED TO THE INSTITUTE BY
MR. T. JOHN TAYLOR.
Up to a very recent period the attention of geologists has scarcely been
directed to the facts which chemistry is capable of supplying in support
of the doctrines of their science, although it admits of no doubt that
the analysis of rocks and comparison of their chemical characters may,
in many instances, materially contribute to the solution of its
problems, or to the determination of disputed points. Of late, however,
the chemical investigation of the volcanic rocks of Iceland and of some
other districts has led to interesting results, and though the
stratified rocks in some respects afford a less promising field of
inquiry, much valuable information may be derived from a knowledge of
their chemical composition.* In regard to this class of rocks, we are
still almost entirely'des-titute of chemical information; and, under
these circumstances, I venture to hope that the following analyses of
the rocks of the coal formation may not be without value, in so far as,
to the best of my knowledge, none of them—with the exception of coal
itself—have yet been analysed. The analyses were made in the laboratory
of Dr. Anderson of Edinburgh, to whose kind assistance and encouragement
I have been much indebted during their prosecution.
The rocks analysed were taken principally from Buddie's Hartley
* We recommend to the particular attention of students of the chemistry
of rocks the many valuable memoirs of Mr. M. A. Delesse in the Annates
des Mines, &c.; and also the important Lehrbuch der Chemischen und
Physikalischen Geologle of the celebrated Dr. Gustav Bischof.—Edit, of
Edin. Phil. Jour.
Vol. TIL—Sept., 1854. c
12
Colliery in the Newcastle coal field, and, though few in number, are
calculated to throw more light on the general constitution of such rocks
than might he at first sight expected, each specimen being selected as
the type of a family, the members of which differ little in their
physical or chemical properties; so much so, indeed, that no difficulty
exists in referring any individual stratum to the family to which it
belongs.
On examining the section of the coal field, a certain definite
arrangement of the beds is apparent, and a tendency to the repetition of
small groups of strata—each group consisting of the same, or nearly the
same, series of rocks. The succession of the members of those groups is,
of course, liable to a certain amount of variation, individual beds
sometimes disappearing or "cropping out''—and so destroying the
uniformity of the series; but it may be observed generally that each
seam of coal is the centre of a group, and is enclosed above and below
by a succession of strata more or less impregnated by a bituminous or
coaly matter, those in immediate contact with the coal partaking so much
of its character as to be capable of undergoing combustion, which in
receding from it they become gradually more and more earthy, until
eventually all trace of organic matter is lost.
The succession of the rocks in each group, taking them in the most
general point of view, is as follows, in descending order :—
Fire-clay or Thill.
Sandstone.
Blue shale.
Bituminous shale
Coarse coal (sometimes Cannel).
Coal.
Coarse coal.
Fire-clay.
This succession, as already observed, is not absolutely invariable, for
even sandstone is occasionally found in contact with the coal, and other
strata (as clay iron-stone for instance) are sometimes associated with
the foregoing, whilst in other instances one or more members of the
group are entirely wanting. But these are exceptional cases, the
arrangement in the majority of instances being that which I have given
above. The rocks employed for analysis were as far as possible selected
from one group, and embrace all its characteristic members, so that from
the analysis of these few substances we have a tolerably correct idea of
the composition of the rocks of the whole formation.
The actual order of superposition of the specimens analysed is as fol-
V
13
lows:—The order is ascending, and figures are attached to the strata
analysed.
Feet. In.
1. Fire-clay (or Thill) . . 2 0 in
thickness Coarse coal . . .07.,
2. Good coal . . 5 2
„
3. Coarse coal . . 0 3
„
4. Bituminous shale . .32,,
5. Blue shale, or slate-clay .31,,
6. Micaceous sandstone . .07,, Blue shale (again) .
0 10 „ Sandstone (again) . . 0 7 „ Blue shale,
inclosing nodules \ q 1
of ironstone . . j
"
Bituminous shale and coal .06,,
Ironstone with shells . 1 11 „
7. Muscle-bind . . .06,,
Before entering upon the details, it may be desirable to glance at the
methods of analysis.
Carbon and Hydrogen were determined by combustion with chromate of lead,
copper turnings being made use of for the deoxidation of any nitrous
acid formed during the process. Nitrogen by Warrentrap and Wills'
method. The Sulphur was determined by deflagrating the substance with
pure nitrate of potash and carbonate of soda, precipitating with
chloride of barium, and calculating the sulphur from the sulphate of
baryta obtained. Ash of coals by complete ignition in a platinum
crucible. The Inorganic substances were estimated in the hydrochloric
acid solution. The portion not soluble in acids (or a substance in
the first instance only slightly affected by them) was fused with a
mixture of carbonates of potash and soda, and the analysis conducted in
the usual manner. The alkalies were determined in some instances by
fusion with carbonate of baryta, in others by attacking' the substance
with hydrofluoric acid. The carbonic acid was determined in the
ordinary way. All the substances were dried at 212°; and in those which
contained no organic matter the water of combination was determined by
ignition. The details of the analyses are as follows:—
No. 1. Fire-clay.—Sp. gr. 2*.519, of a 'grey colour, streak dull, very
soapy to the touch. It constitutes usually the basement of each coal
seam. As that from " Buddie's Hartley" was not a fine specimen, one was
taken from the base of the coal at Blaydon Burn Colliery in Tyne-side,
where it is made use of for the manufacture of fire-bricks, &c.
14
Composition.
Water of combination . . . 10-524
Lime ..... -668
Magnesia . . . .
"746
Peroxide of iron . . . 2-008
Alumina .... 27-753
Potash .... 2-189
Chloride of sodium and sulphate of soda '439
Silicic acid .... 55-500
99-827 No. 2. Good Coal.—Sp. gr. 1*259, fracture conchoidal.
Interspersed rather abundantly with iron pyrites; depth from surface 64
fathoms; is from the " Low main seam/' principally used for steam
purposes, to which end it is largely exported.
Composition. Carbon .... 78-690 Hydrogen
.... 6*000
Nitrogen .... 2-370
Oxygen .... 10-068 Sulphur ....
1-509
Ash.....1-363
100-000 Ash of the above.
Peroxide of iron . . . 14-237
Alumina .... 10-883
Lime . 8-915
Magnesia .... 1*010
Potash .... 1-039 Chlorine, traces
Sulphuric acid . . . 8-210
Silicic acid .... 53-151
TJnburnt charcoal . . . 2-657
100-102 No. 3. Coarse Coal.—Sp. gr. 1-269; fracture slaty; lies
immediately over the good coal; and the bed varies from two to six
inches in thickness. It contains a large amount of iron pyrites, and
is put to no useful
purpose.
Composition.
Carbon .... 70-307
Hydrogen .... 4-714
Nitrogen .... 1*446
Oxygen .... 5*433
Sulphur .... 1*236
Ash..... 16-864
100-000
15 Ash of the above.
/Lime .... 1-286
» Magnesia .... 0*420
*« Iron .... 2-187
< Alumina .... 21-231
•S Potash .... 2-200 J« Soda, traces
g Sulphuric acid ... 1*705
02 Silicic acid - -
1-118
I
---------30-147
-a /Lime, traces
4? Magnesia .... 0-662
.g Iron, traces
,® ( Alumina -
6-530
ji Silicic acid .... 60-812
'g Unburnt charcoal and loss - - 1-849
£ \
---------69-853
100-000
No. 4. Bituminous Shale.—Sp. gr. 1-860; rests on coarse coal; two to
three inches in thickness; black, hard, and brittle, of a slaty
structure; contains impressions of the Flora of the period.
Composition.
Carbon .... 26*700
Hydrogen - -. - - 2*630
Oxygen .... 9.090
Nitrogen - - - -
*934
Lime .... 1-027
Magnesia - - - -
*519
Protoxide of iron - ¦ - 4*275
Alumina .... 19*347
Potash .... -839
Soda .... -374 Chlorine, traces
Silicic acid .... 34-276
100-011
No. 5. Blue Shale (Slate-clay).—Sp. gr. 2-536; in thickness about three
feet; of a bluish-grey colour; is of a much more earthy appearance than
last, on which it rests; is softer and not so slaty, and is studded with
nodules of ironstone. Is nearly related to the fire-clay, both in
composition and physical properties.
16
Composition.
Water of combination - - 11*083
Lime -
0-595
Magnesia - - - - 1-377
Peroxide of iron ... 4*569
Protoxide of iron - 4*545
Alumina .... 23*290
Potash .... 2-089 Chloride of sodium, traces
Sulphuric acid, traces
Silicic acid .... 52*452
100*000
No. 6. Micaceous Sandstone.—Sp. gr. 2*598, over last, varying from six
inches to six feet in thickness; of a fine white colour, close-grained,
and with small plates of mica, very conspicuously seen.
Composition. Water of combination -
6*888
Peroxide of iron - - - 9*539
Alumina .... 8-126
Lime .... 1-112
Magnesia .... 0*325
Potash .... 1-655
Soda .... 1-859
Silicic acid .... 70-257
99-761 No. 7. Muscle-Bind.—Sp. gr. 2*592; in thickness, six inches; is a
clay-ironstone, thickly embedded with indurated shells of a brown
colour> and very brittle. This bed resembles the muscle-bind of the
Derbyshire and Yorkshire coal-fields; and is found also in the
coal-fields of Scotland-It lies, in this instance, at the depth of 62
fathoms from the surface, or
9ij feet above the " Low-main coal."
Composition. /Organic matter and water of combination 11*221
Protoxide of iron
18 637
TS Manganese, traces
^ Alumina ... - 1*194
<s Lime .... 4*084
'^ \ Magnesia ... - 1*078
£§ Chloride of sodium, traces
4 Potash .... 1*319
02 1 Silicic acid, traces
\Carbonic acid - - - 14-057
.5 /Oxide of iron, traces
----------51*590
<d «3 Alumina - - -
16*292
1-1 Lime .... 0*988
'o <j J Magnesia ... - 0*288
| VSiliSic acid -
31*068
---------- 48*636
100*226
1?
No. 8. Cannel Coal.—~Sp. gr. 1*319; is a black, homogenous mass, hard,
brittle, and capable of taking a fine polish; fracture conchoidal.
Though not in the section of u Buddie's Hartley," is often found in
connection with the coal, as roof, base, or even interstratified with
it; that analysed is a fine specimen from " Blaydon Main" colliery, in
Tyneside.
Composition. Carbon .... 78-056
Hydrogen .... 5*805
Nitrogen .... 1-854
Oxygen - - - -
3*119
Sulphur .... 2*223
Ash .... 8*943
100*000 A comparative view of these analyses leads to some interesting
results, and appears to indicate a pretty close connection between some
of the members of the coal formation.
Comparing the organic constituents of the different coals and bituminous
shale, it will be observed that they so far resemble one another, as all
to contain carbon, hydrogen, nitrogen, and oxygen, and a general
similarity is apparent in the quantitative relations of these elements.
But this relation is to a great extent concealed by the variable
proportion of inorganic matter which the substances contain, aud becomes
much more striking when the ash is substracted, and the composition of
the organic part calculated on 100 parts. When this is done, we obtain
the following numbers :—
Coal. Coarse Coal. Cannel Coal
Bituminous
Shale. Carbon - 81*01 85*83
87*36 67-84
Hydrogen - 6*17 5*75
6*53 6*68
Nitrogen - 2*44 1*76
2-09 237
Oxygen - 10*38 &6Q 2*53
23*11
100*00 100*00 100*00 100-00
From these numbers it appears that all these substances present a pretty
close resemblance, except the organic matter of the bituminous shale,
which is very much richer in oxygen than any of the others. This
difference, however, is more apparent than real, and I believe it to
depend upon the method of analysis employed, by which any water which
may exist in combination with the inorganic constituents, comes to be
determined along with, and reckoned as part of the organic matter. I " I
shall have occasion, in discussing the inorganic constituents of the
rocks to show that the inorganic part of the bituminous shale does in
all pro-
18
bability contain water, the exact amount of which cannot, in presence of
organic matter, he determined by analysis, but which, from other
considerations, would appear to amount to about 6-6 per cent. If we
therefore subtract from the organic matter of the shale the quantities
of hydrogen and oxygen corresponding to 6'6 per cent, of water, and then
calculate the result upon one hundred parts, we obtain the following
numbers, which agree in a remarkable manner with those obtained from
the good coal.
Carbon - - 81-62
Hydrogen ... 578
Nitrogen ... 2-84=
Oxygen _ _ - 97(5
100-00 These analyses may then be considered as establishing the fact,
that the organic matter which permeates the strata of the coal-formation
is chemically identical with coal itself; in fact, that bituminous shale
differs in no respect from coal, except in containing a largely
preponderating amount of ash, and that whatever may have been the manner
in which coal has been formed, bituminous shale must be produced under
precisely similar circumstances. The analyses appear, however,
further to indicate the existence in the coal field of vegetable matter
in two different phases of decomposition, for the cannel and coarse
coals contain a very much larger amount of carbon, and smaller of
oxygen, than the other two, which ap-proximate very closely to one
another in composition. Now the gradual decomposition of vegetable
matter is attended by the gradual diminution of the oxygen present,
carbonic acid, which for every six parts of carbon carries off 22 of
oxygen, being gradually evolved, and it is fair to admit that the
composition of the good coal and organic matter of the bituminous shale,
indicates a less advanced state of decomposition than that of the other
two; and as it must be manifest that all are exposed to the same causes
of decomposition now, the difference which is observed must be due to
causes operating before the deposition of the superincumbent
strata.
The analyses of the inorganic constituents of the different rocks also
afford evidence of a certain connection among the different members of
the formation, though it is less obvious both on account of their
greater complexity and the certainty of their being, in some instances,
mere mechanical mixtures, liable to great variations. If, however, we
compare only that portion of certain of these substances which is
insoluble in acids, and which analysis shows to be of constant
composition, we arrive at
19
some interesting conclusions. The whole of the fire-clay, with the
exception of small quantities of lime and potash, is insoluble in acids.
Now, the clays already known to us, are definite mineral compounds,
presenting an invariable composition. Porcelain clay, for instance, is a
hydrated sesquisilicate of alumina represented by the formula 2A12 03
3Si 03 + 3HO, and the same composition is found in all our purer clays,
and the fire-clay of the coal formation is also a definite silicate,
though not identical with porcelain-clay, its composition, setting aside
as non-essential the small quantities of lime and potash, corresponding
very closely with the formula Al„ 03 2Si, 03 + 2HO. Now, the same clay
can be traced in other members of the coal formation; thus the
muscle-bind is a mixtur3 of this silicate with carbonates of iron and
lime. This connection is not seen as the analysis stands, but becomes
apparent by comparing the fireclay, calculated as anhydrous, and the
insoluble matter of the muscle-bind calculated to 100 parts.
¦v;~„ «i„,r Insoluble matter
r ire-clay. „ , ,. ,
J of musle- bind.
Silicic acid - - 62-14 63-89
Alumina - ' - 31-07 33'49
Peroxide of iron - 2-24
Lime - - 0-74 2-01
Magnesia - - 0.83 0-61
Potash - - 2-45
100-00 100-00
Here the sole difference appears to be that, in the fire-clay, a small
quantity of alumina is replaced by the isomorphous peroxide of iron, and
both lead to the same formula Al2 03 2Si 03. This represents both
substances as anhydrous, but the fire-clay contains water in
combination, corresponding, as before observed, to two equivalents, and
it admits of no doubt that the insoluble matter of the muscle-bind, as
it exists in the rock, is also hydrated, although, from the presence of
organic matter, it is impossible to determine the amount of water in an
accurate manner. An attempt was however made to determine the quantity
of water by gently heating the substance so as to avoid decomposing the
organic matter; and in this way 3-08 per cent, of water was obtained,
but obviously no reliance can be placed upon this as a quantitative
determination, because it was impossible to obtain sufficient heat to
expel the whole of the water without destroying the organic matter, but
it is sufn- * cient to establish the fact that water actually was
present.
The blue shale and inorganic matter of the bituminous shale, form
another pair very similar .to one another, though different from the
fire-Vol. III.—Sept., 1854. d
so
clay. In order to render this similarity apparent, I give the results
of the analyses calculated, the blue shale as anhydrous, and the
inorganic
matter of the "bituminous shale in 100 parts.
Blue shale. Bituminous shale.
Silicic acid - - 58-99 56-51
Alumina - - 26-19 31-89
Peroxide of iron - 5-14
Protoxide of iron - 5*11 7-04
Lime - - - 0-67 1-69
Magnesia - - 1-54 0-85
Potash - - - 2-34 1-38
Soda - - - .. 0-61
100-00 ' 100-00 In these two substances, in addition to
silicic acid and alumina, we have a large amount of bases with one
equivalent of oxygen, among which protoxide of iron and potash
predominate. The relation of silica to the sesquiatomic bases is the
same in both, alumina in the blue shale, being in part replaced by
peroxide of iron, and though the quantity of monatomic bases in the
bituminous shale considerably exceeds that in the blue shale, still the
similarity of the two is sufficiently striking. It will be observed
that, in the above calculation, both substances are represented as
anhydrous, while the blue shale actually contains 11 per cent, of water.
I infer, however, from the analogy of the two substances, that the
inorganic matter of the bituminous shale must also be a hydrated
compound, containing the same proportion of water which I have
accordingly supposed it to be in the calculation of the constitution of
its organic part, given in page 147 of the " Edinburgh New
PhilosophicalJournal,"
for Jan., 1851.
The inorganic matter of the other rocks is too various to admit of any
conclusions being drawn regarding their constitution, although they
present some points of interest, which, however, I shall not at present
attempt to discuss.
In conclusion, I may be permitted to hope, that the results of these
analyses are sufficiently interesting to lead others into the same field
of inquiry, and that from the accumulation of facts we may eventually be
led to some general laws regulating the deposition of the stratified
rocks.
NOTE.—(By the Author.) The minerals of which analyses are given in the
following paper (with the exception of the coals), seem to be a mere
mixture of various substances; their composition, therefore, is not
sufficiently definite to be capable of expression by means of formulae.
But for those substances insoluble in acids, the purity of which can be
more safely calculated on,
21
formulae are given below, though not so much with the expectation of
exhibiting their true composition, as of thus affording a more ready
means of comparison. Formulae for—
Fire clay................KO, Si03 +2 A1203, 5 Si03 +4 HO
Slate clay ..............KO, Si03 +2 A1203, 4 Si03 +5 HO
Micaceous sandstone......CaO, Si03 +2 Af203, 8 Si03 +6 HO
WublematterofmusdeO Ca0j m^+2 ^^ g g.^
Insoluble matter of coarse 3 A1 n 10 a.A coal................}Al2U3>
l«biU3
Insoluble matter of bitu- j FeQ m +2M0 4Si0 mmous shale ........y
' 3 ^23? 3
It is not to be supposed that the silicates have the exact constitution
here given, but simply that these are the results afforded by
calculating the per-centages. Nor does the base of each silicate consist
wholly of the constituent above given, for the constituent in greatest
quantity gave its name to the base. Some of the silicates are
represented with water of combination, others without it, but no
conclusion is to be drawn from this circumstance, as the silicates
apparently anhydrous were ignited previous to analysis, and would
therefore give off their water of combination.
The foregoing analyses were made by Mr. Hugh Taylor, while studying
chemistry in the laboratory of Dr. Anderson, of Edinburgh.
Those which follow, not being yet made public, are to be viewed as an
original communication, which I have much pleasure in making in the
author's name.
Like the previous analyses, these also have been made with the greatest
degree of care, and without reference to time or expence. They may
therefore be safely considered as accurate, according to existing
chemical views and methods.
The most remarkable results are perhaps those showing the alteration in
the chemical composition of coal as it approaches a whin dike, the
particular locality being, in this case, that of Shotton colliery,
exhibiting analyses of the cindered coal adjoining the dike, and of the
coal sixty-three yards from the dike, as compared with the Haswell
Hutton seam in an unaltered state.
I have inserted, by way of note to those analyses, the constituents of
Anthracite from Coalbrook Dale and from Pembrokeshire, on a comparison
with which it appears that the coal at sixty-three yards from the whin
dyke, and before it becomes cindered, may be classed as an An-
22
thracite. This is a curious fact, and naturally suggests that the
formation of Anthracite is due to an action upon Bituminous Coal,
similar to the one which has taken place in the vicinity of the igneous
rock under
consideration.
The quantity of Carbonate of Magnesia in one of the analyses of
Carboniferous Limestone (Holy Island) is remarkable, being upwards of 35
per cent. On the contrary the bed, called the White Bed of the Whitley
Magnesian Limestone, is almost a pure Carbonate of Lime, containing much
less than 1 per cent, of Magnesia. Circumstances like these show the
inadequacy of our present system of generalization, and how much they
require to be modified to make them correspond with the actual
operations of nature.
Analysis.
1. Waste Heap, Buddle's West Hartley.
The sample analysed was a reddish powder, obtained by screening a
considerable quantity of heap; clinkers and stones are, therefore, not
included.
-h /Water of combination - - VoS2
| Lime - -
4J76
!i Magnesia -
™
.2 \ Potash - - - -
-188
jjs I Chloride of sodium - - " *J
3 XSulphuric acid - - -
7'b(5ti -,a.vkq
! Organic matter - - q.^qo
Peroxide of iron - - " °voU
Alumina - - - - ^70
-r • .
1740
Lime -
ftq
Magnesia - /0°£
jrotasn ¦
coo
3 Soda -
"588 -3 Sulphuret of iron, trace
m I Carbonic acid - -
'^g
ySilica * " '
_J___20-335
g /Peroxide of iron - - 11-473
•3 Alumina ' - "
-271
H Lime - "
'456
IS" : : " *»
99*754
23
2. Analyses of Coal from Hutton Seam, Shotton and Haswell Collieries.
Effect of Whin Bike.
Cinder Coal, Coal, 63 Yards Haswell Htjtton
adjoining Dike. from Dike.* Seam.
Including Deducting Including Deducting Including
Deducting Ash. Ash. Ash. Ash.
Ash. Ash.
Carbon - 80-255 92-888 89-916 91768 84-284
84-890
Hydrogen - 2-405 2783 3-441 3-511 5-522
5-561
Nitrogen - 1-170 1-354 2-129 2-172 2-075
2-089
Oxygen - -923 1-068 1-228 1-253
6-223 6-267
Sulphur - 1-646 1-905 1-267 1-293
1-181 1-189
Ash - 13-601 2-019
-715
_______________ioo-ooqI_________loo-ooo_________loo-ooo________
* Analysis of Anthracite, for comparison:—
A from Coalbrook Dale, by Jacquelin. B from Pembrokeshire, by
Sehafhautl.
A B Mean of the Two.
Carbon .......................90-58 ....94'10........92-34
Hydrogen ...................... 3-60----- 2-39........3-00
Nitrogen........................ 0-29 ----- 0-87 ........ 0'58
Oxygen.................. .....3-81 ----- 1-34 ........ 2*57
Sulphur is not noticed, if any
Ash............................ 1-72 .... 1-30 ........ 1,51
100- 100- 100-
3—Analysis of Coke manufactured by Mr. J. Morrison, Fence Houses,
Durham, under M. Barbe's Patent, the impurities being separated from the
" Dust Coal," by Washing.
From From
Hutton Seam. Low Main Seam.
Carbon - - 93-150 - 91-658
Hydrogen - - -721 - 708
°x7gen ] - -905 - 1-296
JNitrogen S
Sulphur - - 1*276 - 1-183
Ash - - 3-948 - 5-155
100-000 100-000
24
4.—Analysis of Hobberlaw (Carboniferous) Limestone,
Alnwick. Carbonate of Lime ... 96-986 Carbonate of
Magnesia - 1*006
Peroxide of Iron and Alumina - - '590
Sand.....1-209
99-791 5.—Analysis of Carboniferous Limestone, North Sunderland.
Carbonate of Lime - 96*637
Carbonate of Magnesia . - - 1*938
Peroxide of Iron and Alumina - - *526
Sand.....-707
99*808 6.—Analysis of Holy Island (Carboniferous) Limestone. (Top-bed.)
Carbonate of Lime - 59*280
Carbonate of Magnesia - - - 35*121
Iron and Alumina - 3-746
Sand -
1*384
99.531 7.—Ditto Bottom-bed. Carbonate of Lime ... 96-234
Carbonate of Magnesia - - 2*076
Iron and Alumina - -242
Sand.....1*273
99-825 8.—Analysis of Ironstone from Cleveland. Sample analysed was from
Eston Nab, Cleveland Hills, Yorkshire, the bed being 16 feet in
thickness, and apparently of the same quality throughout.
Lime.....5-803
Magnesia -
3*504
t, . . i /. T C Metallic Iron 36*951) -q-,0
Protoxide of Iron j 0xyg<eQ 10.g67 J 47818
Manganese—traces - - - ......
Alumina - ... 6*499
Chloride of Potassium, with a little) -. n,-0
Chloride of Sodium - j rU0J
Sulphuric Acid—traces - - ......
Carbonic Acid - - - 24*939
Silicic Acid .... 7-257
Water of Combination and a little or-) „ , ?-.
ganic matter ~ " )
100 023
25
Above combined (?).
Carbonate of Lime ... 10*292
Carbonate of Magnesia - - 7*228
Carbonate of Iron ... 43*487
CT i f Peroxide of Iron 21*0571 Silicate Alumina
. 6.499
awUL^ -{Silica - - 7*257 V 37*964
Alummate w , en ^
Cy „ Water or Com* «ki
ofIron' L binaticm } 3151_ Chlorides of Potassium and
Sodium - 1*052
100*023
27 NORTH OF ENGLAND INSTITUTE
OP
MINING ENGINEERS.
MONTHLY MEETING, THUESDAY, OCTOBER 5th, 1854, IN THE ROOMS OP
THE INSTITUTE, WESTGATE STREET, NEWCASTLE-UPON-TYNE.
Nicholas Wood, Esq., President of the Institute, in the Chair.
The minutes of the Council having been read by the Secretary,
Tiie President begged to call attention to the large accumulation of
books which lay at present useless in the Institute, several gentlemen
had spoken to him of the difficulty they had in obtaining a copy of the
proceedings. He, therefore, thought it would be advisable to place their
books in the hands of some London publisher, with a view of advertising
them, so that parties wanting them may have no difficulty hereafter in
getting* copies, as they would then know where they were to be had. If,
therefore, it met the approbation of the meeting, as he would be in
London in a short time, he would endeavour to make some such arrangement
with some of the London publishers.
Several members having expressed their hearty concurrence in such a
course, the suggestion of the President was at once adopted.
The President next informed the meeting that the reason the members had
not got the last paper of the year's proceedings arose from the
circumstance of Mr. Hall's paper being much longer than at first
intended, but he was glad to say that it was now all printed, and would
be in the hands of the members by Monday first.
The following members, who had been proposed at the last monthly meeting
were ballotted for, and unanimously elected, viz:—Mr. Joseph Vol.
III.—Oct., 1854. e
28
Cowan, Blaydon Burn; Mr. Edward Jones, Lilleshall Iron Works, Shiff-nal,
Salop; and Mr. John Browne, Overseal, Ashby-de-la-Zouch. Several new
members were proposed for ballot at the next meeting. The President then
said that they were promised last month a paper by Mr. P. S. Reid, but
as that gentleman had been prevented from illness in completing- his
paper, and was unable to attend, they would not have the paper until the
next meeting. There were, however, two papers before them for
discussion, and there was also the Appendix to the Northern Coal Field,
by Mr. Hall, which, although printed, had never been read at the
Institute. One of the papers deferred was Mr. Greenwell's on the East
Somersetshire Coal Field, and the other, Mr. Hedley's paper. He supposed
that if any observation had to be made on these two last-named papers
they must be in the absence of the authors, as it seemed not at all
likely they would be present. He thought, however, that they could not
better employ their time that day than in reading the Appendix of Mr.
Hall's paper, and in examining the Map of the Coal Field.
The Secretary then proceeded to read the Appendix, which occasionally in
its details called forth some discussion, but it principally consisted
of explanatory remarks relative to certain portions alluded to by the
President, Mr. Potter, and other members, but more especially as to what
was considered the deepest point of the Coal Field, After the Appendix
was finished,
The President complimented Mr. Hall upon the usefulness of his work, and
thought his suggestion regarding a model of the Coal Field well worth
the consideration of the Institute. He, therefore, solicited the opinion
of the Institute as to what could be done by way of accomplishing so
desirable an object.
Some discussion then ensued, in which, all who took part seemed to be
favourable to the construction of a model; and finally, the following
resolution was unanimously agreed to :—
" That the Council be requested to take into consideration the
practicability of constructing a model, or plans and sections,
illustrative of the Coal Field of this district, together with the scale
upon which such model or plan ought to be constructed; and that the
Council also take into their consideration Professor Owen's application
for plans and sections, or specimens illustrating the Geology of the
Northern Coal Field, for the Parisian Industrial Exhibition."
The President next referred to the further consideration of Mr.
Greenwell's paper, and especially referred to the strata which crosses
the overlap " faults" of the Coal Field of Radstock. This he
considered
2d
rather extraordinary, and to his mind the overlap appeared the effect of
the dyke producing a lateral slide of the strata, so as to cause one
portion to overlap the other.
After a brief discussion the subject dropped.
The President thought it necessary before they separated to refer to
Messrs. White and Grant's Patent Safety Cages for Mines, a model of
which they had then before them, and had also witnessed its mode of
operation. For himself he thought the invention very simple, and likely
to be useful to the trade. It was, therefore, proper that such an
invention should be noticed by the Institute; and, as he then held in
his hand the names of a few of the iron and coal masters of Scotland who
had these cages in use, together with some statements relative to some
accidents prevented by their use, he thought it desirable that they
should be read to the meeting. The Secretary then read the following
:—
Names of a few of the more prominent Iron and Coal Masters of Scotland,
with the
number of Patent Safety Cages they have in constant use in their Works.
In use. Orders to make.
William Dixon, Esq., Govan Iron Works................ 12 ..
0
Calder Iron Works................ 15 .. 0
" " Possell Colliery.................. 8
.. 0
Monkland Iron and Steel Company........;............ 20 ..
6
Langloan Iron Company.............................. 14 ..
14
John Wilson, Esq., Dundyvan, Kinniel, Lugar, and Muirkirk
Iron Works........................................ 24 ..
30
William Baird and Co., Gartsherrie...................... 8 ..
32
Carron Iron Co., Falkirk .............................. 18 ..
. 12
Lochgelly Iron Company .............................. 10 ..
0
Forth Iron Company ................................ 20 ..
2
Combination of Airdrie Coal Masters .................... 15
.. 0
Archd. Russell, Wishaw Collieries ...................... 10
.. 0
Lord Bellhaven ...................................... 4 ..
0
Duke of Buccleugh.................................... 3 ..
0
Duke of Hamilton .................................... 8 ..
0
John Horn, Esq....................................... 6 ..
0 ,
195 96 In short every coal master in Seotland has more
or less of them.
Note of a few of the Accidents prevented by our Patent Safety Cages.
June, 1851.—At Stephenson Colliery, Holytown, four men from being1
overwound on a two-story double cag'e, the engine being beyond the
control of the engineman, caused by the breakage of the tramp.
July, 1851.—Rope broke at Omoa Iron Works: cage arrested with its load.
At this work there are sixteen in constant use, and there would have
been frequent accidents, both from ropes breaking and overwinding, but
happily prevented by their adoption.
July, 1851.—Barleith Colliery, Kilmarnock, cage and load prevented from
being overwound. A similar accident occurred previously to getting our
safety cages, when the damage done to the machinery cost upwards of £70.
Sept., 1851.—Five boys' lives would have been sacrificed by being
overwound on a very high pit-frame, at Forth Iron Co.'s Works. The cage
and its valuable load were safely arrested underneath the pit-head
pulley. Also, one instance of a rope breaking-with a man on the cage ;
and very numerous instances with loads of minerals.
Feb., 1852.—At Govan Iron Works, the rim of a pit-head pulley broke, the
sudden jerk severed the wire rope, but the cage and its load were
arrested 50 fathoms from the surface, with a load of two tons.
30
Feb., 1852.—At Carron Iron Co.'s Works, a cage overdrawn with one man on
it: it was safely arrested underneath the pit head pulley.
Dec., 1852.—At Springhill Colliery, Bailieston, cage and load overdrawn:
in consequence of the dense fog, the engineman did not see the mark on
the rope.
Mr. Ainsworth, of Cleator, Cumberland, states, that in consequence of
the short distance between platform and top of pit-head frame, the cages
were frequently overwound and much damage done; but since the adoption
of our safety cages, those kind of accidents have been entirely
prevented.
May, 1852.—Mr. James Stuart, Omoa Iron Works, informs us that there have
been nearly twenty instances where accidents would have occurred at
their pits, both in overwinding and ropes breaking, which were
effectually prevented by our safety cages.
June 2, 1852.—Two men overdrawn at Mr. Russell's pit, Wishaw but were
safely arrested at the top of pit-head frame. Mr. Russell says that it
is worth the price of twenty cages.
Oct. 8, 1852.—Mr. Dixon's Pit, Rutherglen. Accident prevented by
overwinding: one man on the cage.
March 10, 1853.—Mr. Watts' Pit, Slamanan. Rope broke, two men on the
cage; they were instantly arrested, having sustained no injury.
March 11, 1853.—At Mr. Robert Bell's Pit, Wishaw, one cage and man
overwound; but being arrested, sustained no injury.
Sept. 14, 1853.—At Duke of Hamilton's Pit, Redding Colliery, a cage and
one man overdrawn; sustained no injury.
Dec. 9, 1853.—At Kilmarnock, a boy on the top of hutch of coal was
overwound; sustained no injury.
Many numerous other instances of more recent date could be given, but
the above will give the idea of the kind of accidents usually occurring
and prevented.
The meeting then separated.
31
f NOETH OF ENGLAND INSTITUTE
OF
MINING ENGINEERS.
MONTHLY MEETING, THURSDAY, NOVEMBER 2, 1854, IN THE ROOMS
of the institute, westgate street, newcastle-on-tyne. Nicholas Wood,
Esq., President of the Institute, in the Chair.
The minutes of the last meeting-, together with the proceedings of the
Council, having been read, the meeting proceeded with the election of
the following gentlemen, who were declared to be duly elected members of
the Institute:—Mr. John Walker, Wakefield j Mr. Kicbard Cordner,
Crawleyside, Stanhope j Mr. John Trotter, Newnam, Gloucestershire.
Mr. Reid next proceeded to read his paper "On Practice with Gas at
Blowers."
33
ON PEACTICE
WITH
GAS AT BLOWERS.
BY MR. P. S. REID.
In introducing the subject which has been chosen as the title of this
Paper, it will not be amiss to refer back, and take a retrospective
glance at the history of that tremendously destructive power existing
under the name of " Carburetted Hydrogen Gas/' which is so well worthy
of all our energies to endeavour to guard against its effects.
The first accurate views of the real nature of Carburetted Hydrogen are
due to Dalton, some time about 1770 or 1780, and they have been followed
up most instructively by Henry, Thompson, Davy, Faraday, &c.
The subject, however, of the normal condition in which gases are found
in mines has sadly lacked investigation in a practical manner', so much
has this been the case as to cause us to enquire how this is ?
It appears to me to admit of a reply, and to some extent this may be a
true one, that the genius of Davy when it invented the safety lamp, at
the same time that he presented society with such a boon, gave us also
an overweaning confidence in its efficacy, which caused us to relinquish
enquiries as useless, when difficulties could be so easily combatted
with so exquisite an invention, and that in many cases the gift has been
accepted without due regard to its properties, and, in others, it has
been thought that further investigation was unnecessary.
Our attention having been now pointedly directed to this matter by Mr.
Taylor, let us hope it is only a beginning, and that many new facts will
be contributed to so interesting a subject; let me, for my own part?
anticipate that they will be more conclusive than what I am now going
34
to present you, which I regret to say is defective from several causes,
the chief of which is, that it was not put into its present shape till
long after the occurrences narrated, and with the lapse of time I need
not repeat here, that memory becomes defective in many little points
essential to accuracy.
With these remarks I proceed to say that in the Pelton Colliery, about
270 yards to the west of the present drawing- shafts, there is a dip
trouble which throws down the Hutton seam 10 fathoms to the westward,
and brings down the low main seam, which at the shafts is 10 fathoms
above it, exactly even at the point referred to ; hence, in passing
through the trouble we have the Hutton on one side and the low main on
the other.
The course of this trouble is nearly north and south, and both to the
north and south of the point at which the fault was found to have a
downthrow of 10 fathoms; the main trouble diminishes in size in the
first direction, at a distance of three-fourths of a mile to 4 fathoms,
and in the other towards Waldridge Colliery, where it is known about a
mile off to be a 6 fathom downthrow to the westward. Hence, it is
evident that where the trouble has been cut is about the point of
greatest depression of the strata, caused by the downthrow fault.
In the years 1845-6, it became necessary to explore the coal to the west
of this trouble, with the view of supplying the colliery demand.
For this purpose, a drift was made in the direction as shewn on the
annexed plan, and as the Hutton seam was known to have a natural rise of
about 7 fathoms to the westward, in the 270 yards from the pits to where
the trouble was proved, this drift was driven dead level, so as to cut
out as much as possible of the downthrow, and so as (by continuing on)
to take advantage of the natural rise of the seam west of the trouble,
and cut it at the lowest possible level.
No brattice was used in this drift, but the airage during its
prosecution was effected by staples, sunk as shown at the points A and B
on the plan and section, that at A being sunk from the old Hutton seam
waste, and that at B from the Low main seam, into which a place was
driven of such size as to furnish a proper return air course (after the
coal should be won) communicating with the Hutton seam waste, and thence
to the upcast shaft, about half a mile to the north-east of the point B.
Whilst this drift was in progress several large feeders of gas were met
with, mostly in the hard white whin stone post between the two stapples,
which, as it was desirable to avoid the use of brattices, were conveyed
into the returns by means of 2 bore holes, 3 inches in diameter, put
down from the Hutton seam waste, which thus answered the double purpose
of
35
a temporary return, and cleared the drift of the gas as fast as it
accumulated.
By these means we arrived at the point C where, with the view of not
spending too much money by driving in a very hard stone, it was
determined to sink down upon the coal and ascertain its position, and it
was found at a depth of three fathoms below the drift, with its regular
rise to the westward, and we thus had encouragement to proceed to the
westward with the expectation of cutting the coal at a distance of 144
yards, as indicated by the rise of the seam, which appeared here to be
about 1| inches to the yard.
As the stone at this place, however, was very hard, and we required
coals very much, it was determined, in order to gain time, to incline
downwards so as to cut the coal sooner, the drift was therefore drooped
in the direction C D, as shewn by the dotted line, and the coal was cut
at the point D.
Simultaneously with this, the staple B was sunk to E, so as to provide a
return air course in the coal, in preference to driving one in stone,
which would have occupied too much time, and we were encouraged to this
by finding the seam tolerably dry at this place.
So soon as the coal was reached in the drift at D, a place was turned
away both north and south, and after being driven 12 yards in the
former, and 10 yards in the latter direction, was turned east, and thus
driven until each were holed into the staple at E, and a communication
thus effected with the chief return air courses, the southmost of these
bords being driven under the main drift, and thus holed into the
stapple.
With view of providing space for brattice, in case that should be
required, the drift at C was widened out to 9 feet broad by 6 feet high,
but previous to this it was only driven so as to furnish an area of 30
square feet, or 5 feet wide by 6 feet high.
Up to this time so little water had been met with in the progress of the
work as to encourage hopes that these returns might be made available
permanently for the ventilation, and thus avoid some very expensive
stone excavating which might be needed to keep these air courses out of
danger of being filled by water.
The returns, stapple, drift, &c, were, therefore, just finished, as
described, about the beginning of April, 1847, when we again commenced
working towards the westward, and at the point P we met with a rise
hitch, lifting the seam 3 feet 6 inches to the westward, this was
passed, and on the 22nd of April the place was advanced about 5 yards to
the other side of it.
Vol. III.—Nov., 1854. F
36
About 12 o'clock on this day, whilst the deputy was fixing- a prop at
this place, he observed an unusual movement of the thill and immediately
afterwards an immense discharge of water took place, which filled up
both returns, and in a very short space of time was flowing1 along the
drift at the rate of not less than 600 gallons per minute. This
discharge of water was accompanied by gas, but not at first to any
serious extent so as even to fire at the deputy's candle, (which both he
and the men had been allowed to use up to this time), yet there was
sufficient to cause him to retreat, which he did forthwith, and in order
to avoid any accumulation, he opened a manhole door at the stapple, so
as to permit it at once to pass into the returns in the seam above.
Our arrangements being thus so completely and so suddenly foiled, we
were compelled at once to adopt measures to pump the water, and orders
were at once given to lay a set of pumps connected with the main engine,
so as to effect this duty. Meanwhile an attempt was made to pipe the
water, which failed, owing to the gas coming off so strong as to prevent
any one breathing on the inner side of the point Gr, where the stone
approached to 1 foot 6 inches from the surface of the water.
With the view, therefore, of shooting down the stone, a brattice was
put in from the stapple edge so as to allow of 24 feet area behind it,
and
an attempt was made again, with no better success, to get under the
brow at G, we, therefore, began to blast the stone down at this place.
This was begun on the 23rd, at the same time it was evident that the
water had diminished to half its former quantity, or 300 gallons per
minute, but that as the water decreased the gas had increased, until it
began literally to roar and cause a great commotion, lamps being obliged
to be used, and the water boiling like a cauldron with the movement of
the gas whilst passing through it.
We had no sooner commenced blasting the stone, when it became evident
that we had no common blower to contend with, for at the fuse of the
second shot on the 24th, it ignited, and continued after the charge went
off to burn most furiously on the surface of the water with great noise,
alternately coming out in a mass of flame, filling the drift on both
sides of the brattice right out to about 2 yards beyond the stapple, and
then returning under the brow of stone till nearly out of
sight ;:gain.
We at first thought that it would extinguish itself by the motion of the
water, which was very great, lashing up against the roof, but after
waiting some time and finding it did not do so, and that the gas still
continued to advance in a solid flame full 40 yards beyond the brow, and
37
being apprehensive that it might set fire to the coal or render the
brattice useless, it was determined to try to knock it out with
gunpowder. A favourable opportunity was therefore seized, when the gas
had retreated under the stone, and a quantity of gunpowder (about 12
lbs.), was laid with a sufficient length of fuse to enable a man to get
clear out of the way, which he had no sooner done than it exploded, and
by its concussion extinguished the gas.
Our air at this time passing through the drift and round the brattice
end, was quite equal to 10,000 feet per minute, and during the outbursts
of flame alluded to, this was as effectually forced back as if a wall of
masonry had been built across the drift near the stapple, and this at
times would continue for the space of half a minute before it receded
again towards the coal.
Whilst we were busy shooting down this stone, with the view of getting
out of water mark, we were also preparing the lying set of pumps
connected with the main engine, and it was also evident that the water
had diminished to about 150 gallons per minute by the middle of May,
when we were once more enabled to pump the water out and resume coal
working.
From this time to the middle of August it was an incessant fight with
the gas, which seemed, up to the middle of July, to regularly increase
as the water diminished, evidently shewing that the one circumstance was
contingent upon the other, as if following some law, no doubt, arising
from their relative positions prior to the trouble being originally cut
through.
After the middle of July the gas and water both diminished at this
place, the latter to a mere trifling feeder of 10 or 20 gallons per
minute, and the former so much so as to cause us no further trouble,
save that required by the constant use of the safety lamp, for two or
three months after that time.
Frequently during the period, however, up to the middle of July, we had
immense outbursts of gas, far exceeding in quantity the one alluded to
on the 24th of April, which was extinguished by the gunpowder Before
alluding, however, to them, I shall endeavour to shew at what pressure
it issued on that day, so as to give an idea of how the gas increased in
force as the water diminished.
On this occasion, we could not (as we afterwards did) get in to see the
gullet, or fissure in the floor of the mine, from whence both gas and
water were issuing; we could, however, observe it under the brow which
was about
38
1 foot 6 inches from the surface of the water, passing to us with great
force, and at the time of its greatest issue depressing the water in a
wave of about 9 inches in depth. Assuming, however, that the water was
quiescent, we had here an area of 12 feet square, under the brow from
whence gas, coming out in an ignited state, forced hack air which was
passing along the drift at the rate of 10,000 feet per minute through an
area of 30 square feet, and which, at the same time, must have been
passing into the stapple, and no doubt flaming, some distance up in the
return air.
As, however, we could not observe how far this occurred, we must con- •
tent ourselves by saying, that the pressure of the gas passing through
the 12 feet of area would, for the space of more than half a minute, be
bal-lanced, or in a measure, placed in equilibrium with the force of the
atmosphere at the 30 feet area of intake, and the 24 feet of return air
course behind the brattice plus, the motive force, or manometric
pressure of the air, flowing at the rate of 5| feet per second, but, as
the latter would only be about 2 or 3 lbs., we may neglect it in the
present
calculation.
As the point in question is about 120 feet below the level of the sea,
it will be fair to take the atmospheric pressure in this instance at 15
lbs. on the square inch, adding, therefore, the areas of the intake and
return, 24 + 30=54 square feet, or 7770 square inches, the atmospheric
pressure upon which would be equal to 116,6401b., which adapted to the
area of 12 feet, between the brow and the surface of the water, will
give a balancing force of 67| lbs. or 4J atmospheres upon each square
inch of surface
at this place.
Our gas, on this occasion, was ignited, but we had many proofs without
the presence of the flame on several occasions about this time, that the
blower was constantly yielding gas in the same, or even greater
quantities, amongst the rest it frequently ignited at the blast or "
shot," and was extinguished by the concussion and motion of the water,
and on such occasions as we were compelled to use gunpowder it was only
by watching an opportunity, and using the saltpetre paper, that we could
succeed in blasting. It was also often impossible to keep the davy
lamp burning, even close to the stapple, and if you advanced beyond a
certain distance into it, say 4 or 5 yards, your lamp went out, and you
were immediately affected with a strange swimming in the head, and on
attempting to speak you were conscious of your doing so, but could not
hear your own voice, if you still persevered, or remained standing, your
next sensation was a trembling of the knees, and if you did not attend
to this, giddiness ensued, and you
30
fell down insensible. I have frequently seen men brought ought in this
condition, who on recovering their senses in the fresh air, were seized
with vomiting and nausea which lasted several hours, a
Upon the 10th of May we were again enabled to 'get in to the coal, much
of our stone having been blasted down, and our water all pumped out.
Owing to the proof we had had of the blower, it was determined no longer
to rely upon air courses which might be filled up with water. Our air,
therefore, was increased to 20,000 feet per minute, and men were set in
to take the coal off, to the breadth of 10 yards in the north return, as
shewn on the plan at H H, so as the stone could be blasted down to
enable us to have a clear air course, out of the reach of the water, a
stone wall also separated the stapple from the intake air, and in this
wall a proper man-hole door was left, so as to have access to the pumps.
The eruptions of gas I have attempted to describe were very terrific in
their appearance, and the noise which they made in passing through the
water was similar to that of artillery, and had they continued
permanently instead of by sudden outbursts we should have had no choice
in advancing into the coal, but to have increased our air to such a
quantity as to dilute the gas to an inexplosive point. Safety lamps
Avere almost valueless, and I have frequently known every man working in
the returns at K K obliged to retreat out in the dark to the flat, the
only utility of his davy being to warn him of the fact, (which his own
sensations told equally soon,) that he was working in an irrespirable
atmosphere, and that if he did not retire asphyxia would be his fate.
It would be tedious to refer to each occasion when the gas was found to
be most troublesome, I will therefore refer to one or two cases from
which practical deductions can be drawn.
a Since writing the above description of sensations it lias come to my
knowledge that Signor Cardone, an Italian philosopher, published in the
Giornal di Fisica, 1827 the results of some experiments upon the
inspiration of inflammable gases, and as the sensations he describes
coincide to some extent with our own, I subjoin them as follows
premising that experiments of this kind are so rare as to add to the
interest produced by them:—In consequence of the difference of opinion
respecting the effects of the inspiration of inflammable gas on the
lungs, expressed by Scheele Pontana and others the Italian philosopher,
Cardone, lately instituted some experiments on the subject. The air
being expelled from the lungs as much as possible, the mouth-piece of a
bladder containing thirty cubic inches of gas, was applied to the mouth,
and the gas inhaled at two inspirations. An oppressive difficulty of
respiration, and a distressing constriction at the mouth of the stomach
were the first sensations. These were followed by abundant perspiration,
a general tremor over the whole body, seeming to commence at the knees
an extraordinary sense of heat, slight nausea, and violent head-ache. "
My eyes," says Signor Cardone, " beheld things indistinctly, and a deep
murmuring sound was 'in my ears. After a short time all these effects
ceased, except that of heat, which increased in an alarming manner, but
-ultimately, by the abundant use of cold drinks, I was restored to my
original state of health."
40
On the 17th of May whilst we were taking off coal in the north return
the deputy was at the flat above, which was about 50 yards from the
stapple along the drift, the air having been in first-rate condition
just before
when he had visited the men, fully 20,000 feet per minute being passed
through, and he had just sat down when he was surprisedby oneof the
putters
coming out without his light, and his first words were, so soon as he
could
speak, that " he would defy any white man to live in that place, and he
would go back no more."
#
He had scarcely spoken before four of the men rushed out and told the
overman, who by this time had arrived, that it was as much as ever they
could do to get out and save themselves, and that their lights were out,
and they believed there were more men in, as they had stumbled over
some one in the dark, but dare not stop to pick him up.
The overman instantly stuffed his handkerchief into his mouth and went
in with all haste, his lamp went out after he had proceeded about 10
yards from the stapple, and shortly after he felt a tub which some one
was pushing on slowly in the opposite direction, taking hold of this he
gradually backed out, and found, on getting to the flat, that it was a
man of the name Kell who was pushing it, and that the reason why he was
coming so slow was, that he had clutched a boy by the breeches, and was
leaning against the tub for support as well as to help him to find his
way
out.
So soon as they got to the station means were taken to revive the boy
who, as soon as he recovered his senses asked " if the pit had fired."
KelPs account of the matter was, " that he had filled his tub of coals
t( and was waiting of the putter at the place marked L, and that the air
" was tolerably good in his place, thinking however that the putter was
" long he went out to see what was the matter when he had no sooner "
got into the north return than he found his breathing affected, hasten-"
ing on he found the lamp flame getting dim and just at this time he "
fell in with the boy who had fallen down insensible whilst putting his "
tub out, he immediately seized him by the trousers and it was with "
much difficulty he was able to haul him safely out."
He added that he felt the gas so soon as ever he came out into the
rolley-way, coming down with a very strong current towards him.
It would appear from this that the gas had taken the return more rapidly
than the working place where Kell was, and that his air was not (up to
that time) sufficiently diluted to be dangerous, the other men who were
working at the places above and below him were affected in their
breathing and instantly they felt this they retired.
41
The gas on this occasion had not to pass through water but came out of
an open gullet in the floor of the mine, the area of which we could
readily see when it abated to be about 1| inches wide by 10 feet long
crossing the whole breadth of the place or narrow bord.
We were also certain that the air was forced back to the stapple and
that the returns, besides being- quite full both on the south and north
side were pouring their contents as fast as possible up the stapple
towards the low main.
Taking, therefore, all these circumstances into consideration we cannot
doubt that the pressure upon the area of this gullet which only equalled
180 square inches was equivalent to the atmospheric pressure at the
stapple added to the pressure in the intake air course with probably the
mano-metric pressure due to 20,000 feet of air per minute passing
through it. The manometric pressure being only about 7 lbs upon the area
of 36 feet (which was the size of the intake upon this occasion), I do
not think it worth taking into account, especially as it would be
balanced by a corresponding pressure in favour of the gas on the other
side of the stopping. The area of the intake was, therefore, 36 square
feet, and the area of stopple equal to 40 square feet, hence the
atmospheric pressure would be equal to 164,160 lbs.
Applying this pressure to an area at the gullet of the trouble equal to
180 square inches, we have the enormous pressure at the time the gas was
issuing, of 912 lbs on the square inch, or equal to 60"8 atmospheres.
It seems almost incredible, on looking back to it, that we could have so
gTeat a pressure, but it must be borne in mind that this seldom
continued for many minutes, whilst, at the same time, it must be
remembered that not only the air was pressed back in the drift, but
likewise that every possible place in the workings was filled up, whilst
the gas was also flowing up the stapple into the return ; we cannot,
therefore, doubt that great as this pressure was, there is reason to
think that for some seconds, and even minutes, it was still stronger.
Two points are required to be borne in mind with regard to the rapidity
with which the two returns, and the intake or drift air-course were
filled with gas on this occasion, both of which go far to establish the
assumed conditions of equilibrio which I incline to prove. The first is
the amazingly sudden way in wliich the whole area excavated was filled
with gas. To use the words of the deputy, " He had," (after going his
rounds and finding all right,) "just turned his back upon the men, and
sat down at the fiat, when it was announced to him that every place was
full of gas, and it was with difficulty the first men got out."
42
The second is the apparent anomaly of Kell, at the place L, not being so
soon affected to a suffocating extent as the other men, although even he
could not he many seconds after they left before his attention was
aroused, as he described it, by the sudden silence of the pit after the
putter ceased to move.
This may be accounted for by the fact of the gas having pressed the good
air more upon Kell than the other men ; and although the process of
diffusion would be undoubtedly going on, still the time was too short to
admit of this being hurtful to a serious extent.
Again, with regard to the area of space filled in, at the utmost, a
minute of time, the cubic contents of the several air ways would be as
follows:—
The North return.............. 14-139 cubic feet.
The Intake Air-course .......... 16*240 „
The South return .............. 10-665 „
TheStapple .................. 2-600 „
Low Main returns.............. 3-600 „
Total ..........IFoii „
Applying this quantity to the gullet area of the blower, and assuming
the time of its exuding at one minute, we have the apparent velocity of
gas escaping per square inch of surface in that time equal to 261-35
feet, or at the amazing rate of 37,634-40 per square foot of area.
Nor is this all, for it cannot be doubted that when the gas arrived at
the point E, its density must have so far changed as to bring a fresh
element into play; and its velocity in flowing up the stapple would be
accelerated in the ratio of the specific gravity of the atmosphere and
gas at this place.
By this cause its flow along the drift would be checked, and from it we
may assume the reason of its ceasing to flow beyond a certain point, but
remaining stationary at this place—thus causing us to conjecture that
not only was the air current stopped back, but that the gas was flowing
up the stapple, yet not with sufficient velocity, or even with the same
rapidity as it was produced by the blower.
It will from these facts be seen, that in assuming a condition of
equili-brio, we are under rather than above what the actual conditions
of the case would justify.
I have assumed in this that the gas was merely forcing back the intake
air, and not mixing with it; such, however, was not the case, as the
explosion referred to on the 15th June would lead us to infer that the
process of diffusion was in rapid progress.
43
Another and curious feature about this blower was the great degree of
coldness of the gas and water at the point of issue, and even all the
way as far as the stapple.
I am unable now to speak to the temperature in exact terms, our
attention (being too completely concentrated upon measures of safety at
the time) causing us to neglect an examination upon this point; beyond,
therefore, the fact that the men complained bitterly of the cold whilst
working in the water even at midsummer, and that in approaching the
blower when giving out gas furiously, you felt as if a blast of
excessively cold wind was coming against you, we can add nothing
positive with regard to the temperature of the blower itself.
Had I been aware at the time of the importance of every detail, this
part of our practice would certainly not have been neglected, as from
what I shall hereafter refer to, I should conceive the actual
temperature of gas, in its primary issue from the blower, will
eventually prove to be an index of normal tension or pressure.
The actual pressures previously referred to are as close an
approximation as we couid come with the details in our possession, and
to use the words of the workmen whilst the gas was at the worst, and we
were passing all the air we could into it. " it was the same as pressing
it against a stone wall, you couldn't lift her."
We were so fortunate in all the trouble we had with the blower, (which
lasted several months, and though it ignited several times and exploded
once,) as to pass through our ordeal without even a singed hair to any
of our workmen.
The occasion on which it exploded was a curious one, and occurred on the
15th of June.
Six men had been busy shooting down stone, to increase still further the
intake between the stapple and the blower, and had retired to get some
bait or refreshment, to the outside of the stapple, and in order to show
a better light one of them had stuck his candle against the wall at N,
about four feet from the ground, whilst sitting here one of them
happened to look up when he observed the flame suddenly lengthen, and
immediately cried out to his companions that they were all lost, and had
scarcely spoken when the gas exploded; they had started all up at the
same time and were running along the drift as fast as they could, whilst
so engaged the force of the explosion passed over them tumbling them all
head over heels, but not burning any of them.
When they got to the turn at the shaft end of the drift they then looked
back and saw the gas quietly go out of itself.
Vol. III.—Nov., 1854.
g
44
An examination of the drift afterwards showed us that the stopping at
the stapple had been blown down from the intake side, and that a stone
stopping- at the top of the arch at M, had been shifted from its place
all in a lump, although built very strong1 and 7 feet thick.
The remarkable escape of these men can only be accounted for in this
way, that the gas had tailed out as shewn in the annexed plan, and that
although the extremity of the tail would be meeting the air and
gradually becoming more explosive, yet, that none of it was eminently
so> and that though the blast had had sufficient force to knock out the
stapple stopping, yet as soon as it got to the west of this point it
merely ignited the gas and then extinguished itself.
As there were no signs of burns about any of the men, we may come to the
conclusion that their being turned over and over, as described, was due
merely to the motion of the air caused by the explosion, and that this
was also sufficient to move the wall at the point M, which, as before
said, was 7 feet thick. It cannot at the same time be doubted that had
our current of air been less energetic the diffusion would have be£n
greater, the explosion would have proportionably increased in violence,
and that its effects would have been far more serious.
We had also another practical proof of the force of gas coming from this
blower at another time, which is worthy of remark.
In order to avoid pumping the water still exuding from the gullet or
fissure'at the trouble, it was advisable to try and dam back a portion
of it so as to raise its level, and thus get it to flow through pipes to
the level portion of the drift, and thence to our engine pit.
In doing this, we attempted, in the first instance, to put it (the dam)
in close to the trouble because we were rather confined in distance of
coal to make the work secure.
Our first essay proved a failure, from a most unexpected cause, as we
had, without knowing it, planted the dam upon a fissure in the stone,
from whence it was apparent both gas and water was issuing alternately
Our dam was constructed of Memel balks cut in two, and placed one above
the other, clay being beaten in on the inside, so as to make all tight
as we proceeded. The timber was cut 10 feet long, so as to have a hold
on each side, as shewn in the annexed diagram, and we got five pieces in
as shewn, and then began to put in props of larch 9 inches diameter, two
of which we succeeded in getting in, and had nearly gotten in the third
when the pressure from below raised the dam so as to force and literally
split up our props against the roof, like so much matchwood, completely
into shivers, we we1'© thus obliged to shift the position of the
45
dam, 2 feet further eastward, wbere we succeeded in getting- it in with
very little trouble.
During the whole time, however, we had conclusive evidence of the ,
purity of the gas, which frequently forced us to retire for fresh air
above, and no lamp could be got to live more than 5 minutes in it unless
constantly kept moving, the effect of the gas when in its purest state,
was most injurious to the men, not one of whom could remain more than 5
minutes in it at a time when it was at its greatest pressure without
becoming insensible, or on getting out into the fresh air being
excessively sick, as I have before described, and in addition to this if
he continued in for 2 or 3 days occasionally working amongst it, it was
several weeks before he recovered his health and colour.
Having now detailed our practice with this blower during the 4 montbs in
which so much trouble and anxiety was experienced with it, I must now
proceed to such theoretical and practical deductions as this exceedingly
important subject deserves, and which doubtless will be interesting to
the members of the Institute.
In doing so I would wish to divide the subject into three heads, the
first being as to the origin of the gases we meet with in coal mines,
both in the coal, itself and in the circumstance of blowers, as in the
case of Pel ton in 1847, the second referring to such suggestions as
have struck me with regard to contending with inflammable gases in this
shape, and thirdly, with reference to such future steps as may appear
necessary to follow out and investigate more fully than heretofore this
important subject.
1st.—Origin of Gases in Coal Mines.
It appears to me that there are only three positions in which gas can be
simply produced in coal mines. I say simply produced, because I would
submit, that in the case of such blowers as have been described at
Pelton, the gas has not only been produced but stored in a very
remarkable manner, to which I shall hereafter refer, distinguishing it
however from such freshly formed gas as is commonly met with in the coal
itself.
The three positions referred to are as follows, firstly, by mechanical
compression upon seams of coal; secondly, by subterranean heat
acting-upon the coal; and thirdly, by the decomposition of animal,
vegetable, or mineral substances, as in the case of pyrites.
With respect to the third position, it does not appear to me that it can
come into action in coal mines except in the case of decomposed pyrites,
and even in this case it is not the sort of gas which is generally met
with,
46
and that the instances of sulphuretted -hydrogen have not been
sufficiently proved in coal mines to demand more than a passing remark
that it ought not to be lost sight of in future investigations.
Again, with regard to subterranean heat, we have no proof that jts
action" on the seams hitherto reached, are sufficient to produce gas,
whilst, on the other side, we have abundance of proof that it is not the
deepest seams which are most prolific in gas, hence, until more
conclusive proof be had, we must reject the theory that gas is evolved
in coal mines by the agency of subterranean heat.
We find, for instance, that the Monkwearmouth pit, which is far the
deepest of our district, with the single exception of the new Seaton
winnings, enjoys an almost complete immunity from gas comparatively,
with many mines of one-third the depth, and in none of the authenticated
cases of casual or permanent issues of gas do we find temperature at all
alluded to as forming an item deserving attention, of course I speak of
coal-mines, with regard to issues of gas on the surface of the earth,
there are numerous cases, such as in the Caspian Sea, &c. &c, and
chiefly in the neighbourhood of hot springs, whose temperature no doubt
will have some connection with these issues of gas. b
Next with regard to issues of gas by mechanical compression it would
appear from all the evidence hitherto brought forward that this must
depend upon two circumstances, firstly the natural structure of the coal
and the power or force employed, or in other words upon the weight of
strata bearing upon the coal in its natural state in the mine.
In proof of this I would refer to the Hutton seam which is known at
Bedlington as a hard steam coal, and is there almost devoid of issue of
gas, whilst the same seam at Wallsend, Felling, Hebburn, and in the Wear
(but with an entire change in its natural structure,) is notorious for
its production of gas, so much so as even to light up in the tubs, in
which fractured pieces are being brought to bank so soon as you lift a
few pieceS and thrust a candle into them.
Sir Humphrey Davy who I believe has done more than any other man since
the commencement of the present century to inform us of the true nature
of explosive gases, plainly points out that gas is very simply evolved
from coal by mechanical pressure, and with view of proving it he
b The chief places where carburetted hydrogen gas is known to exude on
the surface of the earth, in which the cause is traceahle to the
operations of heat, are at Pietra Mala in the Tuscan Appenines, Iceland,
Pont Gibaud in the Auvergne, and on the west coast of the Caspian
Sea—all more or less the loci of volcanic influences.
47
bruised some large lumps under water, and they gave off inflammable
gas. c
If then, fire damp or gas can be forced out of isolated fragments of
coal simply by bruising them it is not difficult to see what must be the
effect of enormous weights of strata pressing upon coal in the natural
bed especially when further increased by the excavation of large tracts
of pillars and workings.
Supposing that there was no issue from blowers in the barred-up mine,
the case of Percy Main (so accurately described by Mr. Taylor)
establishes the fact that there the natural issue from that seam is at a
pressure of 4^ atmospheres, yet there are cases where the same seam is
almost free ¦ from gas even with the same cover as at Percy Main, hence
this issue must depend upon two causes, viz., the cover and the natural
or chemico-mechanical structure of the coal.
A comparison therefore of all the circumstances connected with cases of
this kind is therefore needed to come to a true conclusion, and I do not
doubt that were such rigidly instituted it will be found that in
proportion to the specific gravity and the several predominant chemical
constituents so will be the pressure at which the gases will issue from
the coal in its natural bed.
Probably a microscopical examination may at some future time lead us to
compare different coals together, or even to measure the minute pores
from which the gases issue, if this could be done a further verification
of this theory might be found.
Again, with regard to blowers, they occur under such different phases it
is difficult to come to an accurate conclusion, with some the gas comes
off dry, and there is a total absence of water, whilst in others it
comes off with water, and it cannot be doubted its issue is intimately
connected with this element, in others again the blower lasts for a few
days or months, and frequently it has been known to endure for several
years. With regard to the Pelton blower of 1847 it ceased very soon
after the
c The fire-damp is produced in small quantities in coal mines during the
common process of working1. The Rev. Mr. Hodgson informed me, that on
pounding some common Newcastle coal fresh from the mine, in a cask
furnished with a small aperture, the gas from the aperture was
inflammable; and on breaking some large lumps of coal under water, I
ascertained that they gave off inflammable gas. Gas is likewise
disengaged from bituminous schist when it is worked. This is probably
owing to the coal strata having been formed under a pressure greater
than that of the atmosphere, so that they give off elastic fluid when
they are exposed to the free atmosphere; and probably, coals, containing
animal remains, evolve not only the fire-damp, but likewise azote and
carbonic acid, as in the instance of the gas sent by Dr. Clanny.—Page
23, Sir H. Davy on the Safety Lamp, and Researches on Flame.
48
final diminution of water, and my own view of its existence is based
upon one of two positions which I shall describe by aid of a diagram.
One peculiar feature of this blower was, that both it and the water came
from the floor of the mine apparently from a lower level, and we find
wherever we have attempted in this mine to go deeper than the Hutton
seam, we have met with gas accompanied with large feeders of water, in
one instance where I bored 200 feet lower we had a large quantity of
water and gas mixed, and from this point the gas has never ceased,
although it is now 5 years since the hole was put down.
My view of the Pelton blower is this: the 10 fathom trouble referred to
so frequently, is a great derangement of strata passing from Farnacres
over by Pelton and so southward over a great extent of country, in this
wide range there must be many crevices or fissures connected with the
main trouble, all acting as service pipes from some head of water,
probably at a very great distance, and that until the moment of cutting
the feeder on the 22nd of April, this column of water had held back the
gas in a highly compressed state, and that so soon as it was relieved of
this pressure, it issued into the mine at the same or even a greater
pressure than that of the water itself, thus:—(See Diagram.)
The question is where have we the height of ground necessary to give so
great a pressure as 9123fos. on the square inch, or 60 atmospheres, to
this I reply that the highest hill of the coal formation in the County
of Durham is probably about 15 or 1600 feet above the level of the sea,
suppose we take it at the latter, we must add 120 feet for our position
below the sea, this gives us 1720 feet as the probable height of water
column in the case of Pelton.
Simply assuming 35 feet as the quantity necessary to balance an
atmosphere, we have 1720-f-35, or 49-14 atmospheres, which taken from
60*8 leaves 11-68 atmospheres still wanting to complete the pressure.
This would, therefore, appear contradictory, but if it is recollected
that the gas and water both came from the floor of the mine, and that
there is no knowing how far these fissures may proceed downwards, we
shall still conclude that there is probability enough left in this
conclusion.
Secondly, we have also the fact that large masses of strata when
separated for a length of time by so incompressible an agent as water,
may, by being relieved of it, suddenly collapse, and thus go far to
explain the pressure of gas and the intermittent character of the blower
I have attempted to describe.
49
Sndly.—Suggestions for Future Contention with Blowers. There are several
points which have been forced upon me by the struggle we had with the
blower of 1847, and which will be applicable to similar cases.
In the first place, I would submit that mechanical or steam jet, or in
fact, any ventilation which, unlike the furnace would have ceased on the
first cessation of the prime mover by the fracture of machinery pipes,
cfec, and whose momentum would end almost simultaneously with that
fracture, would be most imprudent in a case like the Pelton blower.
What, I would ask, would have been the result (if we had adopted me"
chanical ventilation) on any of the great occasions of eruption I have
referred to ? why instead of the gas coming* so far out and reversing*
our air currents it would have mixed and diluted our channels all the
way to the surface, where it would have been very difficult to have
prevented its contact with flame, and who, in such a case as this, could
venture to predict the frightful results with certainty ?
The fact is that the underground furnace is peculiarly adapted for coal
mines, and for blowers of this sort in particular. It possesses a
permenancy of action in the heated shaft which endures long after the
fire itself is extinguished, which is possessed by no other system of
ventilating- power. Although in the case of Pelton this could not be
done but with regard to future blowers, I should strongly advise all
exploring places to be pushed far in advance, where hitches are
expected, and having found the benefit would recommend the returns to
have at least three times the area of the intake, so as in case of
sudden eruption there mig'ht be a space of at least three times the
content to be filled before any backing of the main air current could
occur. The intake should also be enlarged as much as possible.
Lastly, it will be seen how progressively the air current was increased
as the gas got stronger in our case, and how, notwithstanding all this,
the the lamps were useless amongst gas of so dense a nature; so much was
this the case as to cause me seriously to enquire whether or not
provided the area of my air currents could be still further increased,
it would not be more prudent to increase their area together with the
returns, and use nothing but naked candles, relying upon the
non-explosive nature of the gas in its pure state, in preference to
leaning too confidently upon the use of lamps, which I feel sure has
been frequently done to a dangerous and improper extent.
3rdly.—Future Investigations. I should after all I have seen be inclined
to consider it by no means
50
conclusive of our pressure being 60*8 atmospheres, because firstly,
there is no doubt considerable quantities of gas would be flowing into
our returns at the time of supposed equilibrio; and secondly, because we
do not know further than the extinguishing of the lamps, coupled with
our own bodily sensation, that this was veritable carburetted hydrogen.
In future it would be well to analyze the gases, as well as, if
possible, to adopt more conclusive measures to determine the pressure.
Amongst other points which it cannot be doubted would throw much light
on the normal pressure of gas confined in the fissures from whence
blowers exude, is the fact of the temperature of the gas at its first
issue into the mine.
I exceedingly regret that more particular pains were not takin in 1847 p
with reference to this subject; and it was only since this paper was
first , read that I have been led to investigate the subject.
On referring to the Annates de Chemie, it appears that Messrs. De La
Rive and Marcet came to the following conclusions "with regard to the
specific heat of gases."
lstly,—That equal volumes of all gases, under the same constant
pressure, have the same specific heat.
2ndly,—That all other circumstances being equal, the specific heat of
all gases diminishes with diminished pressure, in a slightly converging
series, and in a much less degree than that of the pressures.
3rdly,—That each gas has a different conducting power; that is to say,
all gases have not the same power of communicating heat.
Now if these conclusions hold true with gases at all pressures, it will
only require one or two well-established cases of the temperature of
exuding gases, coupled with the analysis of the gas itself, to furnish
at
once an exponent of the normal pressure from which the gas has changed
in its contact with the air of the mine.
The doctrine of the specific heat of gases is a subject beset with great
difficulties, and has attracted the attention of many of the most
scientific chemists of the day; but it is seldom that well-authenticated
instances of the change of temperature experienced by gases in passing
from a state of great compression to a free communication with the
atmosphere can be met with, except in the case of coal mines.
To solve this important question we must call in the aid of the chemist,
and by enabling him to judge of the enormous power by which blowers are
produced, together with the actual composition of our gases, I do not
doubt that we shall arrive at the most practical and satisfactory
results.
With this view our under-ground arrangements ought to be such as to
enable us fearlessly to experimentalize whenever our operations present
us with convenient opportunities, so as to induce scientific chemists,
when
51
convinced of the controul we have against danger, to" come to the aid of
practical mining by the theoretical deductions which is their particular
province, and which practical miners have seldom time to investigate.
There is a well-authenticated case of the change of temperature by
change of capacity mentioned in Brande's Journal, which I append to this
paper. It is there called " Transference of heat by change of capacity"
but is interesting from the great pressure at which the experiments were
tried; and although the gas was allowed to flow into close vessels
instead of the atmosphere, it bears sufficient analogy to the
circumstance of blowers as to make it interesting to the Institute, d
What we still want are well authenticated instances upon this most
interesting subject, to follow out which I would suggest the association
of a few of our members together, so as the question could be more
thoroughly sifted.
Much has yet to be learned, especially with regard to deeper mines than
we now work, and which are at present the unopened book of the future,
encouraging from some circumstances, one of which is, that it does not
at present appear that the deepest mines are either the most prolific in
gas, or have they (so far) presented us with the largest or most
dangerous blowers,
d " Many of the copper vessels in which gas is compressed at the
Portable Gas-works are cylinders, from two to three feet in length,
terminated by hemispherical ends. These are attached at one end to
the system of pipes by which the gas is thrown in, and being so fixed
the communication is opened. It frequently happens that gas,
previously at tbe pressure of thirty atmospheres in the pipes and
attached recipients, is suddenly allowed to enter these long gas
vessels, at which time a curious effect is observed. That end of the
cylinder at which the gas enters becomes very much cooled, whilst, on
the contrary, the other end acquires a considerable rise of temperature.
This effect is produced by change of capacity in the gas—for as it
enters the vessels from the parts in which it was previously confined at
a pressure of thirty atmospheres, it suddenly expands, as its capacity
for heat increases falls in temperature, and consequently cools that
part of the vessel with which it first comes in contact; but the part
which has thus taken heat, from the vessel being thrust forward to the
further extremity of the cylinder by the successive portions which
enter, is there compressed by them, has its capacity diminished, and now
gives out that heat, or a part of it, which it had the moment before
absorbed; this it communicates to the metal, or that part of the gas
vessel in which it is so compressed, and raises its temperature. Thus
the heat of temperature is actually taken up by the gas from one end of
the cylinder and conveyed to the other, occasioning the difference of
temperature observed. The effect is best observed when, as before
stated, the gas at a pressure of thirty atmospheres is suddenly let into
the vessels—the capacity for the parts is such that the pressure usually
sinks to about ten atmospheres.— Brande's Journal, 1826—1827.
Vol. III.—Nov., 1854.
H
NORTH OF ENGLAND INSTITUTE
OF
MINING ENGINEERS.
MONTHLY MEETING, THURSDAY, DECEMBER 7th, 1854, IN THE ROOMS OP THE
INSTITUTE, NEVILLE HALL, NEWCASTLE-UPON-TYNE.
Nicholas Wood, Esq., President of the Institute, in the Chair.
The President called upon the Secretary to read the minutes of the last
meeting", and also of the Council. These having" been read,—
The President said the members for election to-day, were—Mr. Thomas
Wales, of Dowlais Iron Works, near Merthyr Tydvil, proposed by Mr.
Edward Sinclair and himself; Mr. Samuel Hunter, of Tredegar Iron Works,
near Newport, Monmouthshire, proposed by Mr. Edward Sinclair and
himself; and Mr. John Trevor Barkley, at present resident at
Constantinople, proposed by Mr. Edward Potter and Mr. H. G. Longridge.
These three gentlemen were, respectively, elected unanimously.
The President observed that previously to the reading of Mr.
Long-ridge's paper, he believed the first thing, according to their
regular routine of proceedings, would be to enter upon a discussion of
Mr. Reid's paper. But as gentlemen had only had that paper in their
hands a day or two (some, probably, not having yet received it at all,)
it would be, perhaps, more convenient, if it met with the approbation of
those present, to postpone the discussion till next meeting.
This arrangement was unanimously assented to.
Mr. T. Y. Hall intimated his intention to nominate Dr. Richardson as a
member of the society.
Vol. III.—Dec, 1854. i
54
A letter was read from Mr. J. Dumolo, of Dunton House, near Coles-hill,
Warwickshire, requesting the Secretary to give notice of his intention
to nominate Mr. James Holt, of the Stanton Iron Works, near Derby, as a
member of the Institute.
Mr. Longridge then read his paper on "The Coal Fields of the Ottoman
Empire."
In the course of the reading, and subsequently, some questions were
asked by members with respect to its statements.
Mr. T. J. Taylor remarked, that the coal field which had been, thus
described was much larger than he had had any idea of.
In reply to the President, Mr. Longridge remarked that the limestone was
found underlying the grit; and, in reply to another member, he said that
in the district described, hills were thrown up in every direction and
in every form. The whole district was extremely mountainous. In answer
to another question, Mr. Longridge said that the spontaneous combustion
referred to in the paper arose from pyrites, and not from the coal. Some
specimens of coal from the district described in the paper were produced
by Mr. Longridge, and examined by several members.
Mr. Longridge remarked that the Rodosto coal was perfectly cubical, but
there was a difference in fracture between that and the Selivrea coal.
Mr. Dunn observed that the specimen from Selivrea was like a kind of
fossil coal; it looked very like the parrot coal of Scotland.
In reply to Mr T. Y. Hall, Mr. Longbidge remarked that it burnt to a red
ash.
Mr. Hall spoke of coal in certain districts in Austria which was very
like it; it produced very little flame, and burnt away entirely to ash.
The President suggested that Dr. Richardson should be requested to
analyse the specimens, and that the result of his analysis should be
printed to accompany the paper.
It was understood that this was agreed to; Mr. Longridge remarking that
the specimens he produced were perfectly at the service of the
Institute. [Accompanying the paper, it may be here remarked, was the
result of an analysis of several specimens by Dr. Lyon Play fair; which
had been forwarded for that purpose by Mr. Longridge. There were also
appended reports from the Admiralty as to the value of the coal for the
purposes of war steamers.]
Mr. Longridge observed that he did not produce these pieces of coal as
samples of the coal generally in the district. The Rodosto coal burnt
much brighter than the Selivrea coal.
55
In answer to Mr. Taylor, Mr. Longridge remarked that the Erekli coal
differed altogether from a bituminous coal; it burned quite bright, like
Newcastle coal; in fact, it was very little different from the
Newcastle*"coal. Mr. Taylor asked if there was anything of which Mr.
Longridge was aware, that would cause a bituminous coal to assume that
shape.—Mr. Longridge said: Nothing whatever.
The President thought it was a sort of anthracite coal. In reply to Mr.
Hall, Mr. Longridge remarked, that in some instances the coal beds
dipped down towards and underneath the sea.
The President suggested, that Mr. Longridge should prepare a sketch of
the localities to which he had alluded in his paper; giving a larger
sort of outline than could be obtained in an ordinary map. This would
form a very desirable accompaniment to the paper when printed. They were
very much obliged to Mr. Longridge for giving them a description of this
coal field; which to him (the President) was very much more extensive
than he had had any idea of.
Mr. Longridge assented, and promised to prepare such a sketch as the
ehairman had suggested.
The President said, their next proceeding was with reference to a paper
with which they had been favoured by Mr. Atkinson. It was very
voluminous, and he thought it would prove to be a very valuable paper.
It contained, however, so much of analysis that it was scarcely suitable
for reading at a meeting like the present. The Council had examined it;
and they thought it had better be considered as read, and printed in the
proceedings of the Institute : the Society could then come to its
discussion at the next meeting. The President read the various headings
of the paper; which is devoted to the subject of "The Theory of
Ventilation." It seemed (he said) to comprehend everything relating-to
the ventilation of mines; and Mr. Atkinson must have taken a great deal
of pains in the production of such a paper.
Mr. T. J. Taylor remarked, that the paper was valuable as a sort of
compiled history of what had been done up to the present time in
connection with the subject of ventilation.
Mr. Dunn asked, if the paper could be abbreviated. The President said:
Not beneficially. The subject was a very complicated one, branching
out into different sections; and the paper brought their information
down to the present time.
It was understood that the paper would be printed and circulated in the
proceedings of the Institute, and discussed at the following meeting.
56
A Member suggested that as the paper was so voluminous, it should be
divided into four or five papers; which would admit of a more ample
discussion.
The President thought it would be better to have it printed altogether ;
and then it might be discussed at as many meetings as might be
found necessary.
Mr. Atkinson concurred in the Chairman's suggestion; because one chapter
was so linked in connection with the others, that each would be
incomplete without the remainder being printed.
From some conversation it was understood that Mr. T. Y. Hall would
conti'ibute a paper on certain coal fields which he had visited in
Austria; and the President suggested (as he had done with reference to
Mr. Longridge's paper) that Mr. Hall should lay before them at the same
time a sketch of the locality.
Mr. Dunn feared that the Institute too seldom got its papers thoroughly
discussed. Mr. Hall's last paper had never been thoroughly discussed; it
had only been touched upon.
Mr. Taylor would be glad to see the printing of the papers completed
earlier. If the papers were in the hands of members a week before the
meeting, that would be satisfactory. But this was never the case. He
(Mr. T.) did not get his copy of Mr. Reid's paper till yesterday.
The Chairman threw out the suggestion of allowing a month to intervene
after members received the papers before discussing them.
Mr. Dunn feared the interest would be lost by the intervention of other
topics. He thought, with Mr. Taylor, that it would be desirable if the
printing could be forwarded.
The President said, every effort had been tried to accomplish this, but
it had been found impracticable to obtain greater dispatch than at
present. The President suggested that if it were thought Mr. Hall's
paper had not been completely discussed, the discussion could be again
gone into.
The President said, the next subject to which he had to direct attention
was one of very great importance, as the members would have observed by
the circular. It was the question of establishing a Mining College,
connected with this Institute. The Council had sent a few heads of what
was generally proposed to be the outline of such a college. These had
been only hastily drawn up, not under any expectation that they could be
regarded as perfect, but rather as heads for discussion at a meeting of
the members. The Council had considered the subject very
57
seriously, and discussed it at very great length; and they had come to
the unanimous conclusion that the best plan would be for the members to
appoint a committee—or to appoint the Council themselves to act as such
committee—to draw out the details connected with the proposed college
more specifically than was done in the paper before him. Such a
committee would state every thing relative to the college in detail, and
more specifically than was pointed out here. If this meeting thought
such would be a proper course, it would render it unnecessary to go into
a discussion of the different points to-day. It was proposed that a
special meeting should be called, at which the report of such committee
(or of the Council, if appointed) should be laid before the members, and
then its discussion could be entered upon. Perhaps it would save time
if such a course were now adopted. At the same time he should be very
glad to hear any observations which any gentleman had to make upon the
subject, because that might assist the Council in drawing out the
details. The President added that time was especially an object in this
matter, because there had been many applications and inquiries as to
what progress had been made towards the new institution. During a
journey into some of the other mining districts, last week, several
persons had been inquiring when they could send their sons here;
therefore time was of some consequence. According to regular routine,
there would be no meeting* of members next month, being the Christmas
season; there would be no regular meeting till two months hence.
That would be too long a time to defer the subject, which should be
decided upon as soon as possible. If the meeting should think it
advisable to pursue such a course-as he had pointed out, it would be
necessary for the Council to meet this day fortnight.
Mr. Dunn (to the President) : Do you mean that the Council or committee
should report upon each of the heads laid down in this paper ? The
President : Yes.
Mr. T. J. Taylor : Or in any way they may think fit to deal with the
subject—to report at large.
The President : To consider what is necessary for the mining popu-ation
and for the mining engineers. If a Mining College were established here,
no doubt those connected with our chemical manufactories, and, in fact,
all connected with the manufacturing* interests of this and other
districts would send their sons, because it would be adapted to them as
well as to the mining population. But the great object would be to meet
the wants of the mining interest; and it would be for the Council,
58
or the committee whom you may appoint, to adapt the institution as much
as possible for that purpose^—still keeping in mind that it ought to be
generally useful, or it will not be successful.
Some conversation then followed, in which the President suggested
whether it would not be desirable that whatever report was drawn up
should be circulated among the members previously to the meeting for
discussion, so that they might come prepared for such discussion.
Mr. Dunn suggested whether it might not be desirable to encourage
members to send in suggestions to the Council previously to their
drawing up their report.
Both these suggestions appeared to meet with general concurrence; and
the conversation terminated in the unanimous adoption by the meeting of
the following resulution :—
" That the Council shall he instructed to draw up a plan, in detail, for
the institution of a Mining College—giving the scheme or system of
education to he pursued'; the terms of admission; the support to he
sought for such institution, with all other requisite details; and that
this report he laid before a special general meeting of the members of
this society, to be convened for that purpose on this day month, the 4th
January, 1855.
" That, in the meantime, the Council will he glad to receive from
individual members any suggestions that may he deemed useful, the same
to he sent in on or before the 16th instant; and that these resolutions
be conveyed to the members by circular forthwith."
A Member asked if the report of the Council would be circulated at least
a week before the meeting ?
The President said : At least a week, if it could be accomplished.
Mr. T. J. Taylor then directed attention to the following letter, which,
he said, had been received from Professor Airey by Mr. Anderson:—
" Royal Observatory, Greenwich, Nov. 29, 1854. " Dear, Sir,—It will, I
am sure, be satisfactory to you to know that upon working up our
pendulum experiments we have this day come to a set of results, which
enables me to say that the instruments have stood perfectly well, and
that there is every hope that the conclusion will be in the highest
degree trustworthy. The result now obtained is that the force of gravity
is greater at the bottom of the mine than at the top by iotoo Par^ or
that a clock which goes true time at the top would gain 2| seconds per
day at the bottom; and this implies that the general density of the
earth is 27 that of the coal measures; which is a greater den-
59
sity than I expected. I am now encouraged to go on working up every part
of the problem with greater care. And I write this day to Mr. Arkley,
begging him to give me a small piece of information which will guide me
in making preparations for the next step, namely, the accurate measure
of the depth of the mine.
"I am, my dear, sir,
" very truly yours,
"G. B. Airey."
Mr. Taylor remarked, that the experiment was a very curious one, and
gave results much higher than had been obtained by other experiments j
especially by the Cavendish experiments, and those on the mountain
Schiehallion. Mr. Taylor said that on a rough calculation, he conceived
the medium density of the coal measures to be 2236; water being 1000.
Now multiplying this result by 2*7, it gave the mean density of the
earth at 6*3 times that of water; which was larger than they had
hitherto been taught to expect. The nucleus of the earth must therefore
be very heavy.
The President observed, that some experiments of a similar character in
Cornwall, had failed very much in consequence of the difficulty of
getting correct measurement of. depths, and good communications
underground. But in the present instance, the experiments had been much
more accurately conducted; and there was reason to be very sanguine that
some very accurate conclusions would result.
The meeting then separated.
01
NOTES
ON THE
COAL DISTRICTS
*
OF
EREKLI (ANATOLIA), & RODOSTO (ROUMELIA),
IN THE
OTTOMAN EMPIRE.
BY H. G. LONGRIDGE.
In venturing* to comply with, the desire of the members of this
Institute, to give some account of the coal fields of the Ottoman
Empire, now a country on which the attention of the whole world is
rivetted with intense anxiety, I must apologize for the very imperfect
manner in which I can only bring such information before }rou, and beg-
you to bear in mind that it was collected in travelling- through an
extremely mountainous district, destitute entirely of roads, and covered
with one dense mass of forest and underwood, during* wretched weather,
in the months of November and December, and that except where the
principal mine now is I had no opportunity of further exploration.
Another and most serious difficulty I encountered was in having to draw
all the information from the miners I found partially working- the
mines, through an Interpreter not over well skilled in English, and
entirely devoid of any mining knowledge, so as may be well supposed I
received sometimes rather incomprehensible information. Hoping at some
no distant day to give more accurate details respecting those mines
which are now producing the coals for the combined fleets in the Black
Sea, under the working of Her Britannic Majesty's Government; I shall
merely abstract from my journal, adding such remarks as may be necessary
from matters subsequently come to mj knowledge.
Vol. III.—Dec, 1854. K
62
It will first be as well to notice the method in which these mines had
been worked previous to my visit in 1850.
The monopoly of the coal in the Erekli (Heraclea) district, situated in
Anatolia, on the south coast of the Black Sea, belonged to the Sultana
Valide, and other members of the Imperial family, with one or two of the
influential Pashas.
Any person was allowed to open out a seam, and received a certain sum
per cantar (120 lbs.) for the coal on the sea shore; hence arose the
system adopted throughout of working without either skill or capital*.
The principal masters or workers of these mines are Croats or
Montenegrins, who formerly had been brought over to quarry stone at
Constantinople, but on the discovery of these mines were sent up to
them.
Any one having discovered a coal seam within distance of easy carriage
to the sea, applied to the mine Director for leave to work it, which
being obtained, the working commenced by following in the seam from the
outcrop as far as practicable for water or the roof falling in; in very
few instances did I find a place holed round, and they had invariably
begun at the top of the mountain and worked downwards.
The coal being hewen, is carried out on men's or boys' shoulders in
small baskets, each containing about 301bs. or 40Ibs. of coal, or in
case of a large piece, it is slung, and so carried out alone.
The coal was thrown down as near the drift mouth as a convenient place
occurred for mules, horses, or bullock waggons to come for them. As soon
as the master of the mine thought he had sufficient quantity laying in
heaps, which might be three months or more, he applied to the mine
Director for the horses, mules, (fee, to be sent to convey the coal to
the sea shore, where it was carried by them in panniers, and again
thrown into heaps as soon as weighed. This heap was constituted of the
produce of all the neighbouring drifts or mines, and neither screened or
wailed.
When a ship arrived, the coal again underwent the process of being
carried in small baskets to boats containing 4 to 5 tons each, and
thence off to the ship, where the baskets were again resorted to, to put
it on board, next the voyage, another boating and basketing, and at last
the coal was deposited in the dep6t or magazine to await the final
basketing and boating for consumption. Such being the process, and all
bands, pyrites, <fec, &c, going in together, as well as most of the best
seams being naturally tender, it can scarcely be wondered at if the
report from two of Her Majesty's steam vessels announced it utterly
worthless.
63
The village or town of Erekli is situated about 100 miles from the mouth
of the Bosphorus, and is also marked on many maps Penderaclia and
Heraclea, and contains the only safe refuge for ships on the south coast
of the Black Sea, between the Bosphorus and Sinope; and although an open
bay, has deep water close to the shore on the most sheltered side, where
a large depot could easily be made, and the largest ships coaled at any
time by spouts with little expense or difficulty.
Before getting to Erekli, however, I should mention a valley called
Donghus Dereh, from which I received specimens almost similar to the
coal of Uodosto, and entirely different from the coal of Erekli. This
valley is close to the mouth of the Bosphorus. I entertain little doubt
that this then approximates the eastern limit of the coal field
extending west to Lamsaki, and the shores of the Archipelago and north
of Marmora, by Gallipoli, Rodosto, to Adrianople.
The whole of the coal district from Erekli to Amasserah has been
violently disturbed subsequent to the coal formation, hence throughout
the whole district the seams vary in position from perpendicular to an
angle of 20°; also frequently doubled over like a horse shoe, and
twisted over and over in a space of a few hundred yards. In one place
where this was remarkably apparent, the coal had been wrought as a
quarry with a face of about 150 yards.
The first coal I found going East from Erekli was in some debris at
Chambli, about 4 miles distant, the mines here having been some time
abandoned.
The small pieces of coal were perfectly clean, bituminous, cubical
fracture, and burned with a clear bright flame, and little ash; the
shale was such as is here termed tender grey metal. The seam appeared to
be about 4 feet thick.
A small drift not far from here is probably in the same seam which is
here greatly distorted, to judge from the mouths of the abandoned
drifts.
About a mile and a half further, on the top~of a mountain, a 12 feet
seam had been worked open cast, but appears to have contained bands
varying from J an inch to 4 inches.
Were this seam worth working a stone water level drift would cut the
seam at a short distance from the bottom of a ravine, which is very deep
and underievel a great extent, probable proving several seams instead of
one.
At Alijasah, about 8 miles from Erekli, are several seams of good coal 4
feet to 4| feet, but apparently tender.
64
Over the next mountain, probably a mile and a half, lays Choushazar,
probably one of the most curious formations of coal yet seen. The valley
is wider and more open than most of the others; in which a large hillock
about 100 yards by 30 or 40 high, had been partially quarried away
exposing a mass of broken rock run into a conglomerate, with a strong
bituminous coal as the base. Large pieces, apparently all coal, on being
broken were found to be merely a coating of coal over a large stone,
rounded apparently by the action of water. The coal had,
notwithstanding, a cubical fracture, and burnt without much flame. It is
still .more curious that this mass of coal and gravel appears to have
been repeatedly fractured, and the cracks again filled up with coal,
giving the appearance of numerous veins, each intersecting the other.
Can this be explained by imagining liquid bitumen boiling up through
some ancient river bed, in an intermittent manner, and the fissures
produced in the cooling by contraction, again and again filled up at
different epochs. But to what can be due the difference in quality of
the coal injected into these fissures, some being like jet and others
granulated, and containing a portion of quartz ?
On the east side of this valley are seams of 8 to 9 feet in thickness,
containing numerous stone bands 2 or 3 inches apart of various
thickness, and also iron pyrites incapable of separation, causing the
coal to run to a strong clinker, almost a glass. Some of this coal the
trial vessels had got, as the works at these mines had been allowed to
go on, although condemned by me in 1850; and I this year saw a large
quantity in dep6t at Erekli, which was offered for the use of the
combined fleets, but declined.
At about 18 miles, sea measurement, from Erekli Point, on the top of a
mountain, before descending to the valley of Koslou or Cosloo, is a seam
of 8 feet 6 inches thick, nearly perpendicular, and cutting the mountain
ridge nearly at right angles. The quality apparently very good. This
seam had been worked open cast.
Descending from this mountain, the valley of Cosloo is reached, in which
the mines are at present working for the fleets.
At the mouth of this valley is a small bay with a sandy beach; bounded
on the east by the outcrop of the limestone rising rapidly to the north
and west, and forming an almost perpendicular cliif of great height. The
opposite side of the bay is bounded by a sandstone containing quantities
of pebbles and quartz, exactly corresponding to the millstone grit, and
rising in the same direction as the limestone on the opposite side.
65
The breadth of the valley at the mouth is about 400 yards, quite level,
of alluvial deposit, with a ^small river running- down it, and gradually
narrowing for about two miles until it becomes a mere gorge, and at a
mile or two further turns east on meeting the mountain limestone range.
The coal exists on both sides of this valley, but is most abundant on
the east side about one mile from the sea, but seams have been worked
within a few hundred yards of the sea, and Mr. Barkley has now opened
out one of these at the lowest level, in which, though close to the
outcrop with many old drifts to the rise, stz*ange to say an explosion
of fire-damp took place, burning two men severely. This drift was not
more than thirty-five or forty yards in and working to the dip. Firedamp
was previously quite unknown to the native workmen.
The seams are all of good thickness from 4ft. Gin. to 6 ft., and some
more, clean coal, rising north and west. Six seams can be distinguished,
but the frequent troubles render the tracing of any one peculiarly
difficult. A stone drift or tunnel now in progress will cut the whole of
these numerous seams at the lowest level, at distances of 100 to 150
yards, and thus win this mountain of coal as it may well be called.
The general strata is a coarse-g'rained sandstone, some containing
pebbles and coal scarrs. Also several beds of blue shale with a few
ironstone balls, and more rarely a band, but the shales seem to form a
very small proportion to the sandstones.
A tramway is now laid from the mines to the sea on which the coal is
transported in one-ton waggons, drawn by horses, and shipped by spout
into boats to take off to the ships. As much as two hundred tons has
been shipped in one day.
Tubs and trams have been introduced into the mines, and a proper system
of water levels established.
The roof is frequently very bad and requires much timber, but there is
an abundant supply in the immediate neighbourhood, the whole country
being' one mass of forest.
Mr. Barkley, his brother, and four men, are all the English at the
mines, but eight more men are about to proceed there immediately.
Proceeding east over the next mountain range to the next valley,
Zunguldak, or Soungoul, another small bay, is found, similar to that at
Cosloo, but bounded by the coarse sandstone or millstone grit on each
side.
On the west side, a short distance from the shore, a seam, formerly
66
worked, was re-opening out when I was last there (May, 1854). It is a
seam of 9 to 10 ft. thick of excellent coal, and looked very promising'.
But by far the most promising are some 5 seams of 9 to 12 feet thick of
clean coal, much stronger than the Cosloo coal, and of unexceptionable
quality; the inclination is also less, being about 20°. The position of
these seams has hitherto prevented them being worked, being about five
miles from the sea, so that a railway would be required; this is
however, perfectly easy of formation along the bottom of the valley to
an excellent place of shipment.
•
There can be no doubt that both sides of this valley contain other large
and numerous seams, hitherto unworked for want of means of transport to
the sea.
For 9 miles further east the coal seams (outcrop) continually make their
appearance, but few have been worked. One I saw of 20 ft. thick, but
containing stone bands, and many of the other seams gave evidence of
iron pyrites.
At Chatalalsy the limestone again puts in, cutting off the coal measures
say about 28 or 30 miles from Erekli by sea measurement.
Descending from this ridge a plain of great extent of alluvial deposit
is met with, through which a fine large river, the Filios, runs. This
plain and marsh extends almost for 25 or 30 miles, and in it is situated
the town of Barton, 9 or 10 miles east of which are the Amasserah coal
mines said to have been worked by Belgian or French Engineers. There are
several seams here, but contain large quantities of iron pyrites in the
joints of the coal as well as in lumps, so much so as to render this
coal almost worthless, as well as dangerous from liability to
spontaneous combustion, a case of which occurrsd from that cause in one
of the dep6ts at Constantinople during my first visit.
This is as far east as has yet been explored for coal to my knowledge.*
The Cosloo mines now produce about 20,000 tons per annum, but with a few
more skilled European workmen may soon be capable of producing 40,000
tons, and when the tunnel is complete 100,000 per annum may be obtained.
The former cost was 3 piastres per cantar on the shore, and the same for
transport, or about 20s. per ton at Constantinople for what was almost
worthless. Coal of excellent quality could be put on board at 5s. to 6s.
per ton working charges, notwithstanding the high wages of European
workmen.
* It will be observed that Dr. Lyon Playfair mentions a specimen from
Bolon, Casta-moni—No. 3275—which place is considerably further East.
67
This coal makes excellent coke, and, being free from sulphur, would be
admirably adapted for blast furnaces, and there is no want of iron ore
and limestone.
In concluding my remarks on this coal district, there appears scarcely a
doubt that it belongs to the true coal formation immediately overlying
the millstone grit, but which does not here appear to be of great
thickness. The examination of the fossil and organic remains would be of
great value. And these I hope to have forwarded, as well as various
specimens of the strata and coal seams, ere long.
ON THE RODOSTO COAL DISTRICT.
Rodosto, from which I have named this district, is situated on the north
coast of the sea of Marmora, about 90 miles from Constantinople.
Six or seven miles west of Rodosto, the country is mountainous, but I
did not approach near enough to ascertain their nature.
The whole of the country eastward is constituted of long undulating
steppes, very barren of trees, with a red yellow marly soil, containing
many stones, resting on a very friable sandstone, and elevated from 50
to 200 feet above the sea. This sandstone where exposed exhibits
numerous small hillocks like mole hills, composed of concentric layers,
exactly similar to an onion.
Commencing with some mines said to have been formerly worked for the
powder mills, but abandoned in 1847 or 1848, which are situated about 2|
miles west of Rodosto and 1| from the sea of Marmora, I found
considerable quantities of coal in abandoned heaps, and also much shale
in waste heaps. The reason assigned for the abandonment of these mines
was the water being too heavy for them; the seam dipping rapidly into
the hill. There were several old pumps remaining, formed of trees bored
through, 4 to 6 inches diameter. This coal had a perfect cubical
fracture, was rather lustrous, but only ignited with great difficulty,
and then smouldered rather than burnt to a red brown ash, retaining the
form of the original piece, and falling to dust when touched. As this
seam gave every indication of being similar to that on the east of
Rodosto, where I was enabled to see it in the face of the abandoned
workings, I shall proceed to describe it there.
For upwards of a mile east of Rodosto a coal seam is visible; cropping
out along the sea cliffs at a height of about 30 feet above water line,
dipping from the sea north at about 20°. It will therefore soon run
under
68
the sea level. This seam is about 3 feet 6 inches, between two beds of
very friable yellow sandstone, streaked with red veins, easily
disintegrated, and wasting rapidly by the action of the weather :
quality of the coal, same as that already described. About 14 miles
further east, I had again an opportunity of seeing this seam or one very
similar; the greatest difference being less lustrous and without the
cubical fracture of the former seams. I here obtained the following
section.
Section of strata taken about six miles west of Erekli (Roumelia), on
the north coast of the sea of Marmora, May, 1854:—
Ft. In.
Surface soil—red marl and sand, very stony.
Coarse friable sandstone .. ..
• • 5 0
Blue shale .. .. .. . •
• • 3 6
Coarse sandstone .. .. ..
• • 3 0
Coal parting1 .. .. .. ..
• • 0 Oj
Blue shale .. .. .. ..
• • 2 0
Coarse sandstone, with strong girdles .. ..
5 0
Blue shale .. .. .. ..
.. 8 0
Sandstone .. .. .. ..
.. 4 6
Blue shale, mixed with sandstone .. ..
6 0
Coal .. .. .. ..
3 0")
Seggar clay .. .. .. .. *
6 > 50
Coal and stone .. .. .. .. 0
6 j
Seggar clay .. .. .. ..
.. 3 0
SEA LEVEL. Thick bed of sandstone, cropping out and forming a sort of
reef in the sea.
The coal is here at one place bared by the sea, and rises south-east.
Six miles further east is the town of Erekli, and 14 miles further is
Silivria, where I again obtained specimens, and the following section :—
SURFACE SOIL.
Ft. In.
Sand .. .. .. .. ..
.. 6 0
Sandstone .. .. .. ..
.. 14 0
Alternate bands of sandstones and shale, with ironstone balls 6 0
Seggar clay .. .. .. ..
., 3 0
Sandstone, overlying coal seam .. .. ..
12 0
Coal .. .. .. .. ..
.. 3 0
Some English gentlemen, Messrs. Laing, are said to have opened out these
mines some years ago, but they have evidently never been worked.
I found great difficulty in obtaining information on account of the
natives having been compelled to work the mines in former times without
pay, and fearing being compelled to do so again, if they were
recommenced.
Having ascertained the worthlessness of the coal in this district for
steam purposes, in comparison with those already known to me, on which
point it was my sole object to acquire information, T was obliged to
hasten
69
iriy return without further investigations into the interior; but I have
it from good authority that coal corresponding with this exists in the
neighbourhood of Adrianople, and on the opposite side of the Marmora, as
well as on the Island, the same description of coal is found.
I shall conclude this paper by appending an extract from the reports hj
the juries of the Great Exhibition, and Dr. Lyon Playfair's reports on
the different specimens sent to that Exhibition, and subsequently
examined by him.
November 2nd, 1854
DE. LYON PLAYFAIR'S REPORT ON TURKISH COAL SPECIMENS.
Marlborough House, 15th April, 1854. I.—AMASSORA COAL. Amasserah
T^is coa* *s bituminous in character, not unlike ordinary
Newcastle
Black Sea. coaj# In the specimen, which may however be deteriorated by
keeping, it is too friable, that is in a ship's hold it would be apt to
rub down small; it burns with much smoke, which is objectionable for war
purposes, as it enables the enemy to see the ships at great distances;
it lights easily, which is a useful property in getting up steam
quickly, and burns with a good deal of flame. It leaves on burning 3|
per cent, of a Iig-htish red-brown ash—this amount not being- larger
than many kinds of coal in this country.
GENERAL REMARKS.
This coal may be classed (so far as may be judged by the burned
specimen) as an ordinary variety of Newcastle coal, but considerably
inferior to the Welsh steam coals.
II.—liODOSTA COAL. Sea of This coal is quite of a
different character, more nearly resembling
Marmora. Welsh anthracite. It is difficult to light, but
burns readily enough
when ignited. In burning it produces little flame, and almost no smoke.
It leaves 7| per cent, of ash, or more than double the quantity of the
previous coal—it is also too friable; but this may be from the specimen
having been weathered.
GENERAL REMARKS.
In some respects this coal is preferable to the other for war purposes,
if the furnaces of the steam vessels are fitted to burn it, which is a
doubtful question. If they .are, notwithstanding its greater quantity of
ash, one pound of this coal will probably evaporate as much water as a
pound of the former. It is not, however, suited for getting up steam
quickly, which is objectionable ; but, on the other hand, it is less
likely to betray the approach of the fleet to the enemy.
Vol. III.—Dec, 1854. l
70
So far as the hard specimens are to be trusted, I give you all the
deductions that may be fairly made from them, but you are probably aware
that in general these are insufficient to decide the quality of coals.
The best and only reliable test is to put them under a boiler and see
how they work, with special forms of furnace.
Both specimens, however, give promise, and are worth looking after,
though the Newcastle variety is not equal to our best Newcastle coals,
nor is the anthracite variety equal to our good "Welsh anthracites.
I send you the Turkish catalogue, and if you wish the other specimens
when they are identified to be examined, I shall be happy to do them for
you.
Marlborough House, 18th April, 1854. I now send you a general
examination of the other coals sent to me, those from Amassora and
Itodosta having been already examined.
No. 3268—From Drama. This is not a coal but a bitumen, very similar to
Trinidad pitch. In its ordinary state it cannot be used for steamers,
but Captain Cochrane (now commanding a ship in the Baltic, I believe),
has recently discovered a method by which such bitumens may be
advantageously burned in steamers. If this abounds, it might be worth
while to procure from Lord Dundonald (father to Captain Cochrane) a
description of the plan which the latter has so successfully carried out
at the Admiralty and in the river steamers.
No. 3275—Bolon, Castamoni. Asia Minor ^n^s *s a nai'dj
very lustrous, and not too friable coal. It burns
Black Sea. ^(.jj a bright flame, and only moderate quantity of smoke. It
cakes in burning—has a dark-red coloured ash, which amounts to 3*34 per
cent. This is, on the whole, a very good specimen.
No. 3276—Viransher, Asia Minor. This coal very much resembles the
preceding, being hard and lustrous. It burns with much flame, and a good
deal of smoke, not more however than a common Newcastle coal. It swells
in burning—keeps in well when lighted. It gives an ash (very like the
preceding specimen) dark red, and only amounting to T78 per cent. This
is a promisiag specimen of coal.
With reference to my previous letter you will be able to compare these
coals, and will only accept the descriptions as probable indications of
the value, but not as dispensing with the necessity of experiments under
the boiler.
Black Sea. I have caused the most strict search to
be made after the speci-
men of coal from Erekli, and if it is found I shall examine it, and
forward the result to you.
Marlborough House, 18th April, 1854. "We have proved by the original
register that the Erekli coal was never given in to the Exhibition. We
have found, however, six new ones:— No. 3307—A coal from Moldavia; „
.3272—Coal, or rather a lignite from Monastir ; „ 185—Coal, from
Mount Lebanon ; „ 2214—Coal, from Tripoli, Barbary.
71
I presume that these are too far from the scene of action to be worth
analyzing-, but if you think they had better be examined I shall do so
with pleasure.
Dr. Playfair to Sir C. Trevelyan.
Department of Science and Art. I have examined the remaining Turkish
coals, which we were able to identify by the Turkish labels and numbers
upon them, and now send you the results.
Two of the coals are marked 3307, and described as coming from Moldavia.
Both of them are inferior coals, containing a good deal of iron pyrites,
and from 7 to 9 per cent, of ash. They burn with a moderate amount of
flame and smoke, but on the whole are very inferior to the specimens of
coals formerly examined.
Two, if not three, coals were marked with the number 3272, and are
described in the catalogue as being from Monastir. Two of these coals
were very much deteriorated by weathering, but probably in their
original state are not bad coals. They do not appear in the specimens
examined to be very bituminous. One of the specimens contains 3-39 per
cent., and the other 0"583 of ash. They burned without much flame or
smoke, but from the badness of the specimens little reliance can be
placed on the examination.
No. 185 is described as a coal from Mount Lebanon. It is black,
lustrous, but contained a good deal of iron pyrites. It burns slowly and
steadily, and contains 5^ per cent, of a whitish brown ash.
From the inferiority of all those specimens these results must be
considered as merely rough indications of the probable value of the
coals.
BreWi I suppose you are aware that Captain
Spratt has just been
Black Sea. ^0 Heraclea on special service, and that he gives a
most favorable account
of the coal which he describes as being equal to the best Newcastle.
Specimens are expected to arrive in this country in a few days.
EXTRACT FROM REPORTS BY THE JURIES OF THE EXHIBITION OF THE WORKS OF
INDUSTRY OF ALL NATIONS, 1851, PP. 35-36. TURKEY (1835). " The mineral
exhibition of Turkey is represented by a collection of upwards of two
hundred specimens, sent by the Ottoman Government. It was but just
unpacked when the Jury separated, and the specimens were labelled only
in the Turkish language, with which none of the members of the Jury were
acquainted, so that it is impossible for them to state the precise value
of the collection. It appeared, however, to be of some importance by the
variety of the metalliferous ores included, the principal of them being
red hoematite in fine kidney-shaped nodules, lead ores, accompanied by
metallic lead obtained from them, and rather rich copper pyrites." But
that which has chiefly interested us, and requires special notice in
this place, is the presence of twenty or thirty specimens of very good
coal, and the person in charge of the collection having-had the kindness
to translate for us the labels, we are enabled to state the localities
whence they were obtained. All of those localities are distributed over
a range of upwards of forty leagues along the shores of the Black Sea,
the Sea of Marmora, and the Archipelago, whence it appears that the coal
formation must have a wide distribution in this part of the Turkish
empire. The names of the places, beginning from the
72
east, are as follows :—Amastra, and Erekli, on the Black Sea; Vivan, on
the Sea of Marmora; and Scala Nova on the Archipelago, ahout forty miles
from Smyrna. There are also in the collection three specimens from
Rodosto in the Roumelia, twenty-eight or thirty leagues west of
Constantinople; so that if the indications of these localities may he
depended on, the coal formation must exist on hoth sides of the Straits,
hut according to a geological collection from the shores of Amasserah
and Erekli, collected in 1844, and deposited in the Ecole des Mines in
Paris, hy M. de Chancourtoi, Mining Engineer, there is reason to doubt
whether the mineral fuel from the shores of the Black Sea (Anatolia),
belongs to a true coal formation, and it is possible that the deposit is
as modern as the cretaceous period. However this may be, and although it
is possible that mistakes may have arisen by confusing the place of
production with the port of embarkation, it appears at any rate, quite
certain that Turkey possesses, at a small distance from the capital, and
even on the channel of Constantinople a considerable coal field, which
may become an important source of wealth in the development of its
industry and for the purposes of steam navigation.
(Signed) DUERENOY, Reporter,
Paris, Is* October, 1851.
(COPY.)
Admiralty, 17th July, 1854.
_ . „ Sib,'—I am commanded by my Lords
Commissioners of the Adnu%
Black Sea.
ralty to acquaint you, tfer the information of the Lords of the
Treasury,
that some specimens of coal from the mines near Heraclea have been
tested in Portsmouth Yard, and the result appears to be that, though
inferior to Welsh and Newcastle coal, this coal is considered equal to
many of the Inland and Scotch coals.
I have, &c,
B. OSBORNE.
January ith, 1855. Since bringing the above paper before the Institute I
have received the specimens from the Rodosto district, and annex the
specific gravity of various specimens. I hope by the next meeting to lay
before the Institute the analysis of several pieces of the coal from
each of the places whence I obtained the specimens.
No. of Specimen. Locality.
Sp. Gravity.
1 ............SILIVRIA...................... 1-285
2 ............ „ ...................... 1-324
3 ............ „ ...................... 1-250
4............Erekli (Marmora) ............ 1-297
5 ............ „ ............ 1-333
6............ „ ............ 1-282
7 ............Rodosto (East)................ 1-353
8 ............ „ ................ 1-353
9 ............ „ ................ 1-376
10............Rodosto (West)................ 1-425
11 ............ „ ................ 1-378
12............ „............... 1-425
13 ............ „ ................ 1-466
14 ............ „ ................ 1378
Professor Hitchcock gives the analysis of the Erekli (Black Sea) coal as
follows:—
Carbon.................................. 62-40
Volatile matter............................ 31-80
Ashes .................................. 5-80
100-00
Assay Office Laboratory, Newcastle-upon-Tyne, 11th Jan., 1855. Dear
Sir,—We have the pleasure to hand you the results of our examination of
the four samples of coals from Turkey.
Silivria,
Erekli,
Constituents. Sea of Marmora. East of Rodosto. West of
Rodosto. Sea of Marmora.
Gaseous matters ___ 49-50 48-00 48-00
52-00
Fixed carbon........ 43-50 40-00 47-00
40-50
Ashes........„..... 7-00 12-00 5-00
7-50
100-00 100-00 100-00 100-00
Sulphur, P.S....... -40 -66
-29 1-53
Specific gravity ___ 1-346 1-530
1'442 1.402
In coking, none of the samples caked in the least, and the ash is of a
reddish colour.
The coals are evidently better adapted for the manufacture of gas than
for any other purpose.* The proportion of sulphur is not large.
They will also answer for raising steam, but in practice they will not
be so lasting as the English coal, the proportion of fixed carbon being
relatively so small. They will also burn readily, and, as far as we can
judge from the ash, they will not form clinkers.
We are, yours truly,
RICHARDSON & BROWELL. H. G. Longridge, Esq., Northern Mining Institute.
* I much doubt the illuminative power of the gaseous matters.—H. G. L.
73 ON THE THEORY
OF THE
VENTILATION OF MINES.
BY J. J. ATKINSON.
CHAPTER I.
Introductory Remarks—enumeration of the Principal Physical Laws which
affect the Ventilation of Mines.
Some persons, who are engaged in the daily practice of an art, after
observing a few failures on the part of those who have attempted to
introduce improvements based upon false hypothetical views of the art,
come, at length, to consider that no benefit can result from a knowledge
of the true theory of their art j whilst others go so far as to look
upon any such knowledge as being positively injurious, and only
calculated to mislead those who pay attention to it, alleging that
theory and practice never agree with each other.
That the views just named are incorrect, may perhaps appear from
considering that it is only by a knowledge of the true theory that the
practice of any art can be so conducted and regulated as to be certainly
free from empiricism.
The practice of any art can only be improved, in a direct and systematic
manner, by the application of its true theory, in the absence of which,
improvements can only be expected to result from accidental discoveries,
or, at best, from random experiments, coupled with a generalization
which can only be regarded as a partial theory.
74
It is only by the application of the correct theory of an art that the
results of new, and hitherto untried arrangements and conditions in
practice, can he foreknown and predicted.
A correct and perfect theory will always be found to agree with the
results of practice ; and it can only he when hypothesis is confounded
with theory, or when the theory is imperfect or incomplete, that errors
can result from allowing' it to regulate our practice.
While it is freely admitted that something- more than a mere
acquaintance with the true theory of an art is generally required to
lead to success in practice, it is not, perhaps, claiming too much for
theory to say that it is the most useful handmaid of practice.
Considerations of the above character will, it is hoped, he accepted as
an apology for troubling the members of the Northern Institute of Mining
Engineers with an epitome of the physical laws of ventilation ;
accompanied by formulae for making various calculations in reference to
that subject, with examples illustrating their application; and,
finally, with some suggestions as to the possibility of making the
theory of ventilation, to some extent, useful for regulating its
practice.
Enumeration of the Principal Physical Laws which affect the Ventilation
of Mines.
(1.) The volume assumed by a given weight of air is inversely
proportional to the pressure on each unit of surface, under which it
exists, so long as the temperature remains unaltered; so that under a
double pressure air only occupies one half the space; under a treble
pressure it occupies only one-third of the space—and so on; as a
consequence, the density or weight of a given volume of air, varies
directly as the pressure on each unit of surface under which it exists,
when the temperature remains constant; so that, by doubling the pressure
under which air exists, we double its density; and by trebling its
pressure, we treble its density— and so on; provided its temperature
remains constant, while the pressures are altered. This is known as
the law of Mariotte.
(2.) When the pressure is constant, the increase of volume imparted to
air by heat, is uniform and equal for each degree of heat; and the
experiments of Magnus, those of Eegnault, and those of Rudberg, show
that the expansion caused by each degree of Fahrenheit's scale is about
l-459th part of its volume, at zero of Fahrenheit's thermometer. So that
if a quantity of air, existing under a constant pressure, be conceived
to be divided into 459 equal parts, when the temperature is zero, or 0°,
on Fahrenheit's
75
thermometer; then, on heating it to a temperature of 1°, it will expand
so as to occupy 460 of such parts; on heating it to 2° it will expand so
as to occupy 461 of such parts; and in general on heating it to t° it
will expand so as to occupy 459 + t° of such parts. This is commonly
called the law of Gay Lussac.
(3.) The velocity with which compressed air escapes through an orifice,
in a plate so thin as to offer no sensible factional resistance to its
passage, has been found, in experiments by M. Daubuisson and others, to
be equal to the velocity which an unresisted gravitating body would
acquire, by falling through the height of a vertical column of air, of
the same density as the flowing air, just capable of producing, by the
mere insistent weight or gravitation of its parts, a pressure on each
unit of surface exposed by its horizontal base, exactly equal to the
excess of pressure on each unit of surface under which the compressed
air exists, over that under which the medium exists, into which it is
allowed to flow or escape.
(4.) M. Daubuisson found that when air is discharged through an orifice,
or a tube so short as to offer no sensible resistance to its passage,
the stream of flowing air suffers a contraction, similar to that which
is well known to obtain in the discharge of water and other liquids,
which has the effect of reducing the quantity discharged in a given
time, below that which would be due to the velocity if it existed over
an area equal to that of the orifice or tube.
This contraction of the flowing vein or stream is termed the vena
contractu, and in the case of air and gases is found to reduce the
discharge to •65 of that which would be due to the velocity, if it took
place over
the entire area, in the case of an orifice in a thin plate; to •93 of
that which would be due to the velocity, if it took place over
the entire area, in the cas#e of a short cylindrical tube; to •95 of
that due to the velocity, if it took place over the entire area of the
smaller end of a short conical tube, of the form of the flowing vein or
stream; so that the real quantities discharg-ed in a given time, are to
those which would be due to the full areas and velocities, in the ratios
of -65, -93, and -95 to unity, in the respective cases mentioned,
according to the character of the passage through which the discharge
takes place. (5.) When air is impelled through a confined passage, the
pressure per unit of surface, or head of air column, required for its
propulsion, has been found by Peclet, Daubuisson, Girard, and others, to
be proportional to the square of the velocity; or (what is the same,
when the nature and
76
other dimensions of the air-way remain unaltered), to the square of the
quantity of air passing in a given time, divided by the square of the
area of the air-way.
(6.) The pressure or head of air column, required to propel air through
a confined passage, is found to be proportional to the length of the
pas« sage, all other things being equal.
(7.) The pressure, or head of air column, required to propel air through
a confined passage, is found to be proportional to the perimeter of the
sec tion of the passage, all other conditions being the same. •
(8.) The pressure, on each unit of surface exposed by the section of a
confined passage or air-way, or the height of the head of air-column,
required to propel air through such a passage, is found to be inversely
pro* portional to the area of the section of the passage or air-way,
when all other things are equal—so that the greater the surface exposed
to the pressure, the less is the amount of pressure required on each
unit of surface.
If the velocity be supposed to remain constant, then since (6) and (7)
represent the area of the rubbing surface, exposed to the air in its
passage, by the internal walls of the air-way, it appears that the
resistance encountered by the air is proportional to the area of such
rubbing surface, its nature being supposed to be uniform; agreeing in
this respect with the friction found to prevail in the case of solid
bodies, moving with pressure upon other solid bodies ,• for, by (8), we
perceive that the total amount of pressure required to overcome the
resistance remains constant, when all other things are so, whatever may
be the area of the section over which it is to be distributed; the
pressure on each unit of surface exposed by the section varying
inversely as the number of units of surface over which it is to be
distributed—that is, as its area; so that the entire mass of moving air
contained in a passage, may be viewed as if it were one body, exposing
to resistance a certain fixed amount of superfices, and so requiring a
fixed gross amount of pressure to be distributed over its section to
overcome such resistance, when the velocity is constant; and the greater
the area of such section, the less is the amount of pressure requisite
to be applied to each individual unit of such area, in order to make up
the gross amount of pressure required, and vice versa; after the same
manner as the piston of a steam engine, which will require less pressure
on each unit of surface to produce a given force, as the area of the
piston is greater ; and vice versa.
A law, of a similar character to this, is found to obtain, in the case
of the passage of water through pipes.
77
(9.) The pressure required to overcome the frictional resistance,
encountered by air in passing through a confined or enclosed air-way or
passage is found to vary with the nature of the material composing the
inner surface of the air-way, to which the moving air is exposed in its
route, as well as with the mechanical state of such surface.
This law is not found to prevail in the case of water passing through
pipes, or confined passages; the resistance being the same, whatever may
be the nature or state of the inner surface to which it is exposed; from
which it has been inferred, that the moving column of water does not rub
against the internal walls of the pipe or passage, but probably against
an outer, stationary film of water, adhering to the inner surface of the
pipe; so that the surface against which the moving water rubs, would, in
that case, always be of the same character—water; and this would account
for the resistance being always the same, whatever may be the nature or
state of the inner surface of pipes, through which water is transmitted
; so long as the dimensions and form of the pipe, and the velocity of
the water remain constant.
(10.) The absolute amount of pressure, required to overcome the
fric-tional resistance of tubes or air-ways, to the passage of air or
gaseous bodies, was found by Mons. Girard, in his experiments with the
gas-lighting apparatus of St. Louis' Hospital, to be the same for the
passage of the gas used for lighting as for the passage of air;
rendering it highly Probable that it is the same for the passage of all
kinds of gases whatever through the same pipe or passag-e.
(11.) I am not inclined to think that either the numerous experiments
of Pe"clet, or any others with which I am acquainted, are calculated to
determine whether the frictional resistance of air, flowing against the
internal sides of an air-way, varies in any manner with a variation in
the
absolute barometrical pressure under which the flowing air exists, or
the
contrary; yet from analogy, derived from the law which is found to
exist in the case of solids moving, under different pressures, against
other
solids, I have scarcely a doubt, but that the resistance in question is
directly proportional to the barometrical pressure under which the
flowing
air exists. If this conjecture is a correct one, then a fall in the
barometer,
although accompanied by an increase in the discharge of gases in mines,
and by the circulation of air of lessened density, will be accompanied
by
a reduction in the frictional resistance, due to the circulation of a
given
volume of air; so that the same ventilating pressure will put a greater
volume, although perhaps a slightly reduced weight of air, into circula-
Vol. III.—Dec, 1854. M
78
tion, after a fall in the barometer; and hence it seems rather probable,
that any observed connection between a fall of the barometer and
explosions of gas in mines, is more likely to have its origin in the
increased discharge of gases, than in any observable reduction in the
quantity of air circulating; because a fall of the barometer, will
remove as much pressure, per unit of surface, from the top of the upcast
pit, as from that of the downcast pit.
(12). Although, the co-efficient of resistance to the passage^ of air
through a confined air-way or pipe, as will hereafter be shown, has been
found to vary to a very great extent, in cases where heated air has been
used, from its value in other cases, where cool air has been transmitted
through other pipes composed of the same kind of material, yet in these
experimental trials, the condition or state of the internal surfaces of
the pipes, were widely different, in the cases where heated air was
transmitted, from the condition or state of the inner surfaces of the
pipe? through which cool air was transmitted, so that it appears to
remain doubtful whether the mere change of temperature does or does not
affect the co-efficient of resistance ; as the marked differences
alluded to, might evidently arise, either entirely or in part, from the
differences in the temperature of the air; while, on the other hand,
they might arise, either entirely or in part, from the differences in
the states or conditions of the inner surfaces of the pipes exposed to
the moving air.
It appears to be desirable to institute a series of experiments, to
determine whether a change of temperature does affect the resistance or
not, as this question has an important bearing upon the best size of
upcast shafts, for the purpose of ventilation.'
(13.) The experiments, which Mons. Daubuisson made, to determine the
pressure required to overcome the resistance to the transmission of air,
through an enclosed passage or pipe, arising from mere changes of
direction, at angles or elbows in the pipe or air-way, led him to
conclude, that the pressure required for that purpose is always
proportional to the square of the velocity, all other things remaining
constant; or, what is the same, to the square of the quantity of air
transmitted through any given passage in the same time. He also found
the pressure required to be nearly proportional to the squares of the
sines of the angles, formed by the changes of direction of the axis of a
pipe. He states, however, that he did not find the pressure required to
be simply proportional to the number of angles of similar amount and
character; but that, although the resistance increased, by increasing
the number of angles up to a cer-
79'
tain number; yet, after reaching a certain number of angles, he states
that he no longer found the addition of more angles to require an
increase of pressure to overcome their resistance; but, on the contrary,
he found that the pressure required was actually reduced, by any further
increase in the number of angles; so'that 15 angles absorbed less
pressure than 7 angles of the same size and character—a result so
singular and unexpected, that it, and other circumstances, rendered
abortive all his attempts to ascertain the precise law regulating the
amount of pressure required to overcome the resistance offered to the
passage of air through pipes, arising from angles or elbows, so far as
regards the combined effects of their number, size, and character.
On the other hand, Mons. Peclet, after giving the above as the result of
Mon. Daubuisson's experiments, states that bends or elbows in the pipes
used by himself were found to have no sensible influence on the
pressure, required to transmit a given quantity of air, in a given time,
through them; although he altered them for the express purpose of trying
whether they did so or not; and he further states, that he has found one
and the same formula answer for the passage of air through chimneys,
flues, and pipes, whether they were straight or crooked, none of the
elements of the formula having reference to the angles or elbows.
(14.) The pressure per unit of surface, or the height of head of
air-column, required to overcome the additional resistance arising from
the existence in an air-way, of a diaphragm, with an opening in it for
the passage of the air (not including the pressure required to create
the local increase of velocity, at the passing of the opening in the
diaphragm, which opening is of less area than the adjoining air- way)
was found by Mons. Peclet to be very nearly correctly expressed by the
empirical formula :—
±i yI-yI) ................
where h is the height in lineal feet of a vertical column of air (of the
same density as the flowing air), which, by its mere weight or
gravitation, is capable of producing on each unit of area, exposed to
its horizontal base, a pressure equal to that required to overcome the
resistance, arising from the existence of the diaphragm in the air-way;
in which formula, a= the area of the opening in the diaphragm, and A=
the area of the air-way itself, on each side of the diaphragm, both
expressed in superficial feet; V1=the velocity of the air in the
air-way^ and V3=that in the opening in the diaphragm, both expressed in
lineal feet per minute. He found the actual loss somewhat greater than
is given by the formula.
80
The loss of pressure arising- from a diaphragm, as just alluded to,
would appear to be owing" only to the increasedffictional resistance
occurring at and near the opening in the diaphragm, in consequence of
the extra velocity of the air, and not, in any degree, to an expenditure
of pressure, required for the generation of the extra velocity at the
diaphragm (considered as distinct from the effects of such extra
velocity, in increasing the frictional resistance), as Mons. Peclet
supposes; seeing that the pressure due to the extra velocity (excepting
only when the diaphragm is situated so close to the exit-end of the
air-way, that the air actually leaves the air-way with a higher velocity
than that due to the entire area of the air-way itself), would only be
absorbed temporarily at and near the diaphragm, where the increased
velocity prevailed j and after the air had got beyond the influence of
the diaphragm, the moving column would again have expanded the area of
its section, so as to fill the entire air-way; necessarily accompanied
by a diminution of velocity; during the occurrence of which, the
momentum given out by the air would have assisted to overcome the
resistances encountered in the air-way; so that this pressure, required
for the mere increase of velocity, considered by itself, is really not
finally applied in increasing velocity, but on overcoming resistances,
in the form of the momentum of the air carrying it over them.
The actual loss of pressure arising from the diaphragm, being really
that due to the increased frictional resistance in the vena contracta,
as compared with what it would have been if it had not existed, any
connexion between this pressure, and that due to the generation of the
increased velocity at the diaphragm, being that arising out of the fact
of the resistance itself, being increased partly in consequence of the
increased velocity, and no more. A similar mode of reasoning leads to
the conclu" sion, that the only pressure really absorbed by, and
finally.expended upon, the mere generation of velocity, in transmitting
air through a confined passage, in any case, is simply that due to the
velocity with which the air is finally expelled from the air-way, or
part of an air-way, which may be under consideration; as any higher
velocity, which may prevail in any preceding part of the air-way,
although (at the place where it really exists), it may be considered as
temporarily absorbing the pressure due to its generation, yet since the
excess of velocity is reduced, and the momentum of the air given out in
a subsequent part of the air-way, and since such momentum so given out,
as the velocity becomes reduced, really carries the air over the
resistances, to the full amount of the pres"
81
sure, due to the excess of velocity, it follows that it is only the
pressure due to the final velocity, which is really carried off by the
air, without being applied to the resistances offered by the passage.
Again, if we are considering the pressure required to overcome the
resistances of only a portion of a confined passag-e or air-way, it is
evident that if the air arrives at the commencement or entrance-end of
such portion of an air-way, with any velocity greater than that with
which it leaves the exit-end of such portion of air-way, the excess of
pressure, due to the generation of the excess of velocity alluded to,
will really be given out in the form of momentum of the air, cairying it
over some of the resistances encountered in the portion of the air-way
under consideration; and consequently, so much less additional pressure
will be required than would have been, had the air only possessed the
same velocity on reaching the air-way, which it does on leaving it.
If, however, on the contrary, the air reaches the portion of air-way
under consideration, with less velocity than that with which it passes
the exit-end of the air-way under consideration, then, besides the mere
pressure required to overcome the resistances in the portion of air-way
under consideration, there will be a further expenditure of pressure in
creating the increase of velocity, which will be carried off in the form
of momentum, by the air leaving the exit-end of the portion of air-way
under notice or investigation; and the expenditure of pressure on such
portion of air-way will therefore consist of the sum of the pressures
required for the overcoming of the resistances, and for generating the
excess of velocity with which it leaves, over that with which it
reaches, the part of the air-way in question. But if the air enters and
leaves the air-way, or portion of air-way, as the case may be, with one
and the same velocity, then the expenditure of pressure will consist
simply of that required to overcome the resistances, and be unaffected
by any pressure connected with the mere generation of velocity,
considered apart from any increase or reduction of resistances, arising
out of changes of velocity, which may occur in any intermediate parts of
the portion of" air-way under notice, of whatever kind or degree any
such changes may be.
82
CHAPTER II.
On the discharge of air and fluids, under pressure, through orifices or
short tubes: and the pressure due to the generation of motion,
considered apart from that due to friction.
(15.) It is quite in keeping with the known laws of motion, that, as has
been stated, (3), the velocity of a fluid or gas, when not affected by
friction, should be the same as would be acquired by a heavy body, after
falling, under the influence of gravity, through the particular height
required in a vertical column of the gas or fluid, in ord er that the
pressure on its base, arising from the weight of the column, should be
exactly equal to the pressure generating the motion of the fluid or
gas—or, otherwise, to the excess of pressure under which the fluid or
gas exists before escaping, over that of the medium into which it flows
j reckoned in each case on equal areas.
In reference to the escape of water, it is stated in " Adcock's
Engineers' Pocket Book" :—"Supposing a very small cylindrical plate of
water, immediately over the orifice, to be put in motion at each
instant, by means of the pressure of the whole cylinder standing on it,
and supposing all the gravitation of the column to be employed in
generating the velocity of the small cylindrical plate, neglecting its
own motion; this plate would be urged by a force as much greater than
its own weight, as the column is higher than itself, and this through a
space shorter, in the same proportion, than the height of the column.
But where the forces are inversely as the spaces described, the final
velocities are equal. Therefore the velocity of the water flowing out
must be equal to that of a heavy body falling from the height of the
head of water."
(16.) Now by the well known laws of falling bodies, if h' represent the
space or distance fallen in lineal feet; v the velocity in feet per
second, acquired at the end of the fall; and g the distance in feet
which an un-
83
resisted gravitating body falls in the first second of time, which is
found by experiment to be 16^ feet near the surface of the earth; then
v = J4 g hf....................[2j
and since g is equal to 16^ it follows that
v = 8-0208 vrh7~.................[3]
From what has been stated, it is evident that h', in the preceding
formula, will represent the height in feet, of the head of air column,
of the same density as the flowing air itself; which, by the weight or
gravitation of its parts, will generate the velocity represented by v.
That is to say, h' represents the necessary height in feet of a vertical
head of air column which is just capable of producing by its weight,
that particular pressure on each foot of area of surface, exposed by its
horizontal base, which must be exerted to produce the velocity v.
If we know the pressure per superficial foot of surface under which
confined air exists, and represent it by p; and also the pressure per
superficial foot of surface, under which the medium exists, into which
it is allowed to discharge itself, representing it by p' j then, when
the discharge is effected through an orifice in a plate so thin as to
present no observable frictional resistance to its passage, or through a
very short tube under the same conditions, the difference p—p' will be
the pressure per superficial foot of surface, generating the velocity;
and if by w we
represent the weight of a cubic foot of the air, it is evident that ——*-
will represent the height in feet of air column, which would be due to
the pressure generating the velocity; and hence
h'=-2=£ .......................[4] '
W
u J
by means of which equation, the head of air column, due to any
difference of pressure, may readily be found. By transposing [3J we
obtain
h'=w..........................[5]
and substituting in [5], the value of h' in [4], gives
p—p' _ v2 w 64j
and hence,
/ w v2 r/l1
r-F' = -ojj-.................[«1
84
w=64i-E=^. ..................I7|
and,
v = 8-0208 I-5=P-......................181
N W '
'
where v is the velocity in feet per second.
If, however, v' be allowed to represent the velocity in feet per minute,
we shall have
•
V = 481-2 VT.................p|
and,
h' = ipr....................p°]
and by substituting in the latter equation, the value of la! in [4], we
obtain
p-p'= -mm................w
and hence,
w = 231,600 p~?/.............[12]
and,
v' = 481-2 J -^=P- ................[13]
But since the velocity v', actually prevails only over the area of the
contracted vein, and not over the entire area of the orifice or tube,
the quantity of air discharged in a given time will be found by
considering the velocity (found as above) as prevailing only over the
area of the contracted vein: so that if by c we represent the ratio of
the area of the contracted vein, to that of the orifice or tube [4]; and
by A the area of the orifice or tube in superficial feet; then will c A.
be the area of the contracted vein, where c will take the value of .65,
.93, or .95 depending upon the character of the orifice or tube
employed.
And if Q represent the number of cubic feet discharged per minute, then
will
cA
which value of v', being substituted in [9], [10], [11], [12], and
[13] gives rise to the following series of general equations :—
Q = 481-2 c A s/ h' ............[14]
85
li? - (-mhry ¦....................M
A== 481-2 c ,/W ..............^i6]
t _ w Q3
p p ~ 231,600 o8 A8 ............Li/J
and,
Q = 481-2 oaJ^ ....................[18]
by which the relationship existing between the quantity of air
discharged in a given time, the area of the orifice or tube through
which it is discharged, and the pressure employed, is exhibited.
These formulae, however, do not apply when air, instead of
being-discharged without sensible resistance through orifices or short
tubes, has to be propelled, in opposition to the resistances offered to
its passage, through long tubes or air-ways j inasmuch as such
resistances absorb a part of the pressure employed, and leave only the
remainder for the generation of the velocity, considered apart from such
resistances; and in mines these resistances often operate to so great an
extent as to require a pressure 10, or even 20 times greater, to
overcome them, than that which is actually employed in the mere
generation of velocity in the flowing air.
Still, since in all cases the pressure required for the generation of
velocity forms a portion of the entire pressure employed, and so
requires its share of consideration in calculations as to the
ventilation of mines,l has been deemed only proper to give the preceding
formulas, bearing upon this part of the subject under consideration.
Vol. III.—Dec, 1854. x
86
CHAPTER III.
On the amounts of ventilation produced by different ventilating
pressures in the same mine, and the mode of comparing the particular
resistances or " drags " of different mines.
(17.) The laws recited, as prevailing in the transmission of air or
gases through an enclosed passage or air-way, lead to the conclusion
that the pressure required to overcome each separate source of
resistance, (excluding any pressure due to the gravitation of the air in
any ascending parts of the air-way, which, with the effects of the air's
gravitation in descending parts of the air-way, will here be considered
as diminishing or adding to the ventilating pressure employed), is
proportional to the square of the velocity of the air over any given
section of the air-way, and, therefore, to the square of the quantity of
air transmitted in a given time through the same air-way, including the
pressure due to the mere generation of motion or velocity itself; and
since the sum of the separate pressures gives the entire pressure
employed, it follows that, in the same mine, the quantity of air put
into circulation in a given time, will be proportional to the square
root of the entire amount of pressure employed, including under the term
of " pressure employed," the gravitation of the air in the descending
parts of the air-way, diminished by the gravitation of the air,
(reckoned on the unit of surface of area only), in the ascending parts
of the air-way.
^18.) The pressure finally expended on the generation of velocity in the
air, will only embrace that which is due to the final velocity with
which the air leaves the air-way at its exit end; inasmuch as if even
higher velocities do prevail in preceding parts of such air-way, the
pressure temporarily absorbed in creating such excess of velocity, will
eventually be given out as momentum of the air, carrying it over
resistances encountered in succeeding parts of the air-way, as must
appear from the consideration that the flowing air necessarily parts
with a portion of the momentum it possesses, as the velocity of its
motion becomes reduced;
87
which momentum of itself would carry it over a portion of resistances,
if no further power or pressure were applied.
What has just been stated indicates that the quantity of air put into
circulation in any passage or air-way, will be strictly proportional to
the square root of the entire pressure employed, (so long as the air-way
remains unaltered), provided that we include, as a part of such
pressure, the effects of any excess of pressure due to the gravitation
of the air in all the descending parts of the air-way over that which is
due to the air in the ascending parts of the air-way; always reckoning
the descents and ascents as they occur in the direction followed by the
air where they prevail, and reducing them to the unit of surface
employed. Or, on the other hand, the entire pressure employed must be
reduced by the amount of any excess which may be due to the gravitation
of the air in the ascending parts of the air-way over that due to the
gravitation of the air in the descending parts of the air-way, where
such an excess happens to prevail.
(19.) Where steam jets or furnace action are employed, the resistance in
the upcast shaft will probably increase in a somewhat higher degree than
the square of the quantity of cool air in the workings of a mine, as the
air in such shaft will be more expanded as the temperature and the
ventilation are increased, and hence also the velocity of the air
itself.
It is doubtful whether the coefficient of resistance due to friction may
not be increased or diminished by changes of temperature in the upcast
shaft, although Peclet did not detect any such change in it with a
chang*e of temperature.
And it may be further remarked that a mixture of aqueous vapour or steam
with air in an upcast shaft may possibly modify the coefficient of
resistance ; although, as has been stated, it was found to remain
constant for the transmission of either air or the gas used for lighting
St. Louis Hospital, in Mons. Girard's experiments.
In the absence of a positive knowledge as to whether the coefficient of
resistance is altered by variations of temperature or by the presence of
steam in the air or the contrary, it will be presumed, in the following
investigations, that the coefficient in question is not affected by such
change of temperature, nor yet by the admixture of aqueous vapour.
Although the very strict investigation of the laws of ventilation would
require the application of an infinitesimal analysis, yet. for all the
cases which generally occur in practice in the ventilation of mines, the
use of algebra will probably lead to x-esults not sensibly differing
from the
88
truth; and since rigorously accurate observations on ventilation can
scarcely be made by any known means, the latter mode is considered
sufficient for the object in view, and will accordingly be here adopted.
Mathematical niceties, when introduced at all, will be intended rather
to create confidence in the results than as examples to be followed when
applying- the deductions to practice.
Since it would greatly complicate the subject to treat the resistances
as if they varied with a variation in the barometrical pressure of the
air, without, for our purpose, greatly affecting the conclusions- "the
resistances will be treated as if they were not affected by variations
in the barometrical pressure of the air • at the same time it is
probable that the contrary is the fact.
Although the formulae resulting- from the mode of investigation to which
reference has been made, are not, for the reasons stated, to be regarded
as being rigidly applicable to the circulation of currents of air, under
extreme and unusual conditions as to temperature and pressure ¦ yet they
may, perhaps, be regarded as possessing all the accuracy which can be
considered desirable, as applied to currents of air under the usual
conditions prevailing in mines, flues, and chimneys.
(20.) Since the pressures required to create ventilation, cceteris
paribus, are proportional to the squares of the volumes of air
circulated in a given time through the same passages or air-ways, it
follows, that if, by calculation, the quantity of air which would have
circulated under the same pressure over the area of the air-way, if
there had been no resistances beyond the inertia of the air, be found to
be five times as much in the unit of time as is actually observed to be
put into circulation, then only one twenty-fifth part of the pressure
employed is expended on generating the velocity; the whole of the
remaining twenty-four parts out of twenty-five parts, into which the
pressure may be conceived to be divided, being expended on the
resistances in the air-way, because the squares of 1 and 5, are in the
ratio of 1 and 25.
In like manner, if the quantity of air circulated in a given time be
found to be only one-fourth of the quantity due to the area and
pressure* had there been no resistances in the air-way, it follows that
only one-sixteenth part of the pressure is absorbed in expelling the air
from the top of the upcast shaft, or extremity of the air-way while the
remaining 15-16th parts of the pressure is employed in surmounting the
resistances encountered by the air in the mine or air-way. The
conclusions stated are true of any single air-tube or passage, whether
acting alone or as one
89
of a connected or ramifying series, as in a mine in which the air is
divided by splitting into a number of separate currents; always taking
into consideration the entire resistances which any given portion of air
encounters, from the moment it enters the downcast shaft through the
whole of the route taken by it in the passages of the mine, whether
before being split, during its being- so, or after its re-union with the
other currents, to the moment of its being ejected from the top of the
upcast shaft; because it is certain that the air will naturally divide
itself in such particular proportions over the various passages which
are connected together, as to require, in each instance, the same
amount of pressure; and this is as true of the air which forms part of
any minor, or sub-split, as of that which never leaves the main splits
of air, the air in every instance naturally following the route
offering least resistance to its passage, and thus filling each passage
with air of that particular velocity which will raise its resistance to
the same amount as that of each of the other routes in the same mine or
system of ventilation. When, however, from the variations in the
temperature of the air circulating, and differences in the ascents and
descents of the air-ways, there happens to be a greater or less power,
added to or taken from the general ventilating power, in some routes
than in others, this law will manifestly be found to obtain only when
the necessary addition or reduction of power required for each route is
made to take a part in the calculation; the quantity of air circulating
in each route being directly proportional, all other things being'
alike, to the square root of the actual pressure expended on causing it
to circulate; including, in estimating such pressure, the effects of the
natural pressure in each particular route, arising from the temperature
and density of the air in the ascending parts, differing from those of
the air in the descending parts; and since such natural pressure may
differ, not only in amount but even in the direction in which it
operates in one route of any mine, from that operating in any other
route, it follows that the actual pressure operating in the different
routes or splits of air in the same mine, and at the same time, may
differ from each other.
The quantity of air circulating in each route, however, will further be
inversely proportional to the specific resistance of such route,
depending upon its length, the area and perimeter of its section, the
nature of the material of which its internal surface is composed, (fee,
so that the quantities of air in the different routes of the same mine
may, by varying these conditions, come to bear any proportion whatever
to each other. (21.) From the quantities of air being proportional to
the square roots
90
of the pressures employed, other things being constant, we could readily
calculate the quantity of air due to any pressure, when we had observed
that arising from any other pressure in the same mine or air-way; but it
would be a tedious operation to ascertain the actual amount of pressure
employed, when the air-ways had many ascending and descending parts
traversed by air of different temperatures or densities; and these
natural pressures could not be neglected when they happened to bear any
considerable proportion to the artificial pressure employed; and they
would involve the necessity of making a distinct calculation for each of
the splits, and even for each of the minor or sub-splits of air, when
the amounts of natural ventilation in such splits differed from each
other.
Here, however, we will investigate the case of a mine, in which either
the whole of the workings are situated in the same horizontal plane, or,
on the other hand, in which the amounts of pressure arising from the
natural causes alluded to, happen to be of the same amount, and all
operating in the same direction, relative to that of the currents of air
traversing them in each of the splits and minor or sub-splits of air; in
which case the ventilating pressure may be regarded as being the same in
each of the splits of air; and the formulae and results arising may be
considered as approximating nearer to the truth, in proportion as these
conditions are less departed from, in mines where they do not fully
obtain j and as the amount of artificial ventilating pressure employed
bears a greater proportion to any such natural pressure arising in the
airways from the causes stated.
(22.) In the case of furnace ventilation, if we presume the upcast shaft
to have its top and bottom, respectively, situated in the same
horizontal planes as the top and bottom of the downcast shaft; and
suppose, in the first place, that both shafts are filled with air of the
same temperature, then, on heating the air in the upcast shaft, the
expansion of the air would drive a portion of it out at the top of the
shaft, and the weight of this expelled air would operate as if divided
equally over the area in producing ventilation, because the weight of
the air in the downcast shaft would remain the same as before, and being
no longer opposed or counterbalanced by an equal pressure of air on each
unit of surface in the upcast shaft, the entire column of air in the
downcast shaft, air-ways, and upcast shaft would be put into motion.
Experiments (2) on the expansion of air by heat lead to the conclusion
that if any given volume of air, under a constant pressure and at zero
of Fahrenheit's scale of temperature, be conceived to be divided into
459
91
equal parts, such air will increase in volume to the extent of one of
such parts by the addition of each degree of temperature; so that the
volume assumed by it will always be proportional to 459 -ft0, for all
the values of t°, which represents the temperature of the air.
Hence if the air in the upcast shaft be considered to have the same
temperature as that in the downcast shaft, represented by t, and then to
be heated to any other temperature T, it follows that the length of the
column of air of the same area of the upcast shaft, would, by the change
of temperature from t to T, be altered in the ratio of 459-ft to 459 +T,
inasmuch as any given volume of air would be increased in that
proportion. If by d we represent the depth of the upcast shaft in feet,
and by H' the length of the column of heated air at T, expelled from the
top of the shaft by heating from t to T, also expressed in feet, we
obtain the proportion—
As459 + t:459 + T ::d:d+H' And hence the height of the column of heated
air, of the area of the upcast shaft, which is capable by its weight of
producing the ventilating pressure arising from the heat imparted is
H' = d(wr)................t2°]
but since, in the case of mines ventilated by furnaces, the weight of
the column of expelled air would be less in the case of a high upcast
temperature, than it would be for the same length of expelled column, in
a shaft of greater depth with a lower temperature; and since the present
object is to obtain general formulas, for comparing one amount of
ventilation and ltd accompanying conditions with a different ventilation
and accompanying conditions, without, to too great an extent,
complicating the formula?, by an affectation of an over nice precision,
we shall omit making any allowance for the difference of resistance
arising from the difference of expansion in the air, in the upcast
shaft, when two different temperatures are compared; in general, the air
in its entire route will have a temperature more nearly corresponding to
that which exists in the downcast, than in the upcast shaft; and hence
we shall reduce the height of the column of air, due to the ventilating
pressure, to the standard density due to the temperature in the downcast
shaft t; calling the height of the air column of such density H, we have
the proportion
as459+T : 459 + t :: H' : H and hence
H - H' (-^±±\ f211
11 ~ M V 459 + T /................L^J
92
and by substituting in this last equation the value of H' in [20], and
reducing-, we obtain
H = d(TOO ................t22]
(23.) In general the length of air column, or the pressure per unit of
surface, due to the final velocity with which the air is expelled from
the top of the upcast shaft, may be regarded as sensibly the same as
that which would be required to generate the final velocity, which would
have existed, if the air on its expulsion from the top of the upcast
shaft had a temperature T of the same amount as the average temperature
in the upcast shaft; seeing that any slight reduction in volume and
velocity, arising from the cooling and contraction of the air, after
passing the point in the upcast shaft where the average temperature
actually prevails, will have its tendency to reduce the pressure
required for its expulsion from the top of the shaft, counteracted, to
some extent, by the greater density of the expelled air; and hence, for
the sake of simplicity, it is intended to treat the pressure due to the
expulsion of the air, as being the same as it would have been, had the
air retained the average upcast temperature up to the moment of its
expulsion from the top of the shaft.
Now by [10] y,a
h' = 231,600 h' being the height in feet of air column, of the same
density as the flowing air, due to the mere generation of its velocity j
which is represented by V in feet per minute; and if by Q' we denote the
cubic feet of air (of the volume due to the average temperature of the
upcast shaft) per minute; by Q, the same air expressed in volume of
cubic feet, due to the temperature of the downcast shaft t; and by A the
area, in feet, of the top of the upcast shaft, we obtain
v"--4-.....................[23]
and by substituting this value of V, in [10], we obtain
a 231,600 Aa And since the volume of air at the temperature T of
the upcast shaft is to the volume assumed by the same air at the
temperature t, of the downcast shaft, in the ratio of 459 +T to 459+ t,
we have
Q' = Q(S)........................M
93 and therefore
i/_ Q2(459+iy r251
~~ 231,600 A2 (459 + t)2 ................L J
but if we represent by h the height in feet of air column (of the
density due to the temperature t of the downcast shaft), required for
the mere expulsion of the air; since h must be less than h' in the ratio
of 459 + T to 459+ t, we obtain
231,600 A3 (459 +1) L J
now since [22] the entire ventilating column of air at t, the
temperature
(I*__£ \ ' A.rQ "Jj_ T J ' ailC* S"1C0
by [26]
as above h == ooi pnn A a "Ledj i+S represents the portion of such
column
employed in generating- the velocity of expulsion of the air from the
top of the upcast shaft, it follows that the remainder of the column, or
H-h - d ( T~M - Q2 (459+T) r
n U59+T; 231,600 A2 (459 + t) ...........L J
represents the height of such column required to overcome the various
resistances encountered by the air in the shafts and air ways of the
mine.
(24.) This last formula [27], furnishes the means of calculating the
amount of what has recently been termed the "drag" of a mine. It should
however be borne in mind that this drag or resistance will, supposing
the temperature of the air and the conditions of the air ways to remain
unaltered, vary in the ratio of the square of the velocity of the air
over any given section; or what is the same, as the square of the
quantity of air circulating per minute j so that if we would compare the
drag or resistance of one mine with that of another, or of the same mine
under varied conditions, we must calculate or reduce each to some
particular quantity of air in circulation per minute, assumed as a
standard.
(25.) By means of formulae [22] and [26] we may ascertain the
proportions of ventilating pressure absorbed in any mine in the
generation of the final velocity of the air with that required to
overcome the drag of the mine, and so determine the loss of air arising
from the resistances. As examples, let us take the cases of Hetton and
Tyne Main Collieries, as given by Mr. Wood, the president, in his
communication to this In-Vol. III.—Dec, 1854.
©
94
statute in December, 1852, and February, 1853, furnace ventilation being
in existence in eacb case, as below :—
Hetton. Tyne Main.
Area of upcast shaft, in superficial feet ... .153.... 50*257
Depth of do., in lineal feet ..............900___672
Average temperature of upcast shaft ......211°.... 262°
Average do. of downcast shaft.............. 430,5... 44°
Cubic feet of air per minute........225,176......102,503
In the case of Hetton Colliery the entire head of cool air column, of
the density due to the temperature of the downcast shaft employed in
the production of ventilation, is, by [22],
H - d( T"t W 900 (211-43.5) _ n~a\ 459 + T ) 459 + 211
~ ^° teet'
The portion of the above ventilating column expended, in this instance,
on the expulsion of the air from the top of the upcast shaft, is, by
[26], W- Qa (459+T) _ 225,176* (459+211)
,q.rffppt
231,600 A3 (459+t) " 231,600 xl538 (459 + 43-5)
that is, 13*6 feet of air, of the density due to the temperature of the
downcast shaft, t, would produce the pressure required to generate the
final velocity with which the air left the top of the upcast shaft; and
therefore this portion of the ventilating column is carried off, so to
speak, as momentum in the air leaving the top of the upcast shaft, and
is lost to the resistances or drag in the shafts and workings of the
mine, which have therefore to be overcome by the remaining part of the
ventilating column, which will be (225—13,6)=2ll,4 feet of vertical
column of air of the density due to t.
In this case, therefore, only about l-16t,h part of the ventilating
pressure is expended on the velocity or motion of the air, while the
remaining 15-16th parts of such pressure is expended on overcoming the
drag or resistances of the shafts and workings; and since it appears, by
the laws recited in Chap. I. that the quantities of air circulating in
the same mine are, cceteris paribus, proportional to the square roots of
the pressures per unit of surface by which they are put into
circulation, it follows that only V -j^-, or l-4th of the quantity of
air circulates, which would have circulated had there been no drag or
resistances in the shafts and workings; and if it were possible to
remove those resistances, the quantity of air put into circulation by
the same pressure would gradually increase in amount as they were
reduced; but in this mine, with the same pressure, could never exceed
four times the quantity—225,176, or 900,704 cubic
95
feet per minute; because the whole of the pressure, or 225 feet of air
column, would then be required to generate the velocity with which the
air would leave the upcast shaft.
It is highly probable that a smaller proportion than even 6 per cent, of
the ventilating pressure, as in this case, will, in other less
effectually ventilated mines, be employed in creating the final
velocity, more particularly in cases where the upcast shaft is of
greater area in proportion to the extent of the galleries requiring
ventilation.
(26.) In the case of Tyne Main Colliery, the entire ventilating column
is,
H -d (tsbvt) = 672 (mtm-h203'2 feet'
or about .3 of the depth of the upcast shaft, even a higher proportion
than in the case of Hetton, both being exceedingly hot upcast shafts at
the times of observation.
The portion of the ventilating column finally expended on the mere
expulsion of the air from the top of the upcast shaft at Tyne Main
Colliery is,
Q2 (459 + T)___________102,503* (459 + 262)
231,600 A2 (459 + t) ~~ 231,600 x 50-2573 (459 + 44) '
being slightly more than l-8th of the entire ventilating head of cool
air or pressure employed in ventilation; so that, in this instance \/|-,
or rather more than l-3rd of the air circulates, which would arise from
the entire pressure, if there were no resistances to be overcome; about
12| per cent, of the entire ventilating pressure being employed in the
generation of the velocity of expulsion, and the remaining 87 J per
cent, being-absorbed by the resistances in the shafts and air-ways.
(27.) From a published statement relative to Haswell Colliery, we have
The area of the upcast shaft, in feet ........,....... 58
Depth of the upcast cast shaft, in lineal feet.......... 936
Average upcast temperature........................ 165°
Downcast shaft temperature........................ 62°
Cubic feet of air, per minute......................94,900
We have, for the entire ventilating column of air, at 62°, in this
instance,
H =d (mw) = 936(mf) = 154'5 feet>
being rather more than l-6th of the depth of the upcast shaft; the
air-column, of 62°, due to the upcast shaft velocity, in this case, is,
h = ___Q3 (459+T) = 94,900* (459+165) __
231,600 A2 (459 + t) 231,600 x 582 (409+62) ~ °° ieei'
96
So that rather less than 1-llth part of the ventilating pressure is
expended
on the velocity of expulsion, or carried off as momentum by the air
leaving the top of the upcast shaft; the remaining- part, or rather more
than 10-llths of the entire pressure being employed on overcoming the
resistances encountered by the air in the mine and shafts ; the quantity
of air circulating being to that which would have been expelled from the
upcast area, had there been no resistances, in the ratio of */13-84 to
V154-5, or of 3*72 to 12-43, or about 30 per cent, of the latter
quantity.
(28.) For the sake of instituting a comparison between the resistances
which would be encountered by equal amounts of air in each of the three
cases named, Hetton, Tyne Main, and Haswell Collieries, we have
Eetton. Tyne Mn, Hasw.
Temperature of downcast shafts, assumed) ~or ..0
-_0
as that of the head of air-column .... * Height of air-column employed
on the) 005 «">03-° 154-5
resistances and velocity ............5
Air-column due to velocity, only........ 13*6 .. 25-7 ,. 13*84
Air-column due to resistances..........211-4 . .177-5 .. 140-66
Air circulating......................225,176. .102,503. .94,900
Reducing the heads of air-column to a standard temperature of, say 62°,
the heights due to the resistances of the shafts and mines become 219-2
for Hetton Colliery, 183-8 for Tyne Main Colliery, and 140-66 for
Haswell Colliery. The pressures expended on the resistances being
proportional to these quantities, we have now to find the pressure
required to overcome the resistances in each case, on the presumption of
a given and equal quantity of air circulating in each of the mines, in
order to be able to compare their respective amounts of drag ; and,
since the resistances are proportional to the squares of the quantities
circulating in a given time, in the same mine, if we assume 1000 feet
per minute as the standard for comparison, we obtain for Hetton
Colliery,
As 225,126* : 219-2 :: 10003 : -004325;
for Tyne Main Colliery,
As 102,5032 : 183-8 :: 10003 : -01748;
and for Haswell Colliery,
As 94,9003 : 140-66 :: 10002 : -01606.
Hence the head of air column due to the resistances in the shafts and
workings of Hetton colliery would have been -004325 of a foot, when
only 1,000 cubic feet of air per minute circulated :—-01748 of a foot
for
the circulation of the same amount at Tyne Main colliery, and -01606 of
97
a foot for the circulation of the same quantity at the Haswell colliery,
the two latter cases presenting, in fact, each about four times the
amount of the resistances existing at Hetton colliery. From this, it
would appear that if it were practicable and desirable to reduce the
resistances in the Tyne Main and the Haswell collieries by further
splitting the air, or otherwise, to the same value as those at the
Hetton colliery at the time of the observation, an enormous increase in
the gross quantities of air circulating in these collieries would be the
effect.
(29.) The general law of the quantities being proportional to the square
roots of the pressures will enable us to ascertain the quantity of air
which would circulate in a mine at any assumed average upcast
temperature, provided we have first ascertained the quantity put into
circulation by an observed average upcast temperature in the same mine.
Thus, if the quantity of air observed to circulate per minute be Q, when
the downcast temperature is t, and the average upcast shaft temperature
is T; and if d be the depth of the pit used as an upcast, then by [22],
the column of air at t, causing the ventilation, is
H = d(459^T) And if it be required to calculate the quantity of air Q,
which would circulate through the same unaltered mine by altering- the
average upcast shaft temperature to T, and presuming the downcast shaft
temperature to
-jKcrrTp) will be the ventilating pressure due
to the new temperature, expressed in height of air column at t as
before; and since the quantities Q and Q are respectively proportional
to the
square roots of their corresponding pressures d ( -rrq-Trrfr ) and
(21__t \ 4KQ.i"7V we obtain the proportion,
AsQ : Q:: d (¦^~T) : d (J=^)
and hence the equitation ________
§=Q 2|g'...................... [28]
4 459+T which may be expressed thus—
^ ~(459+T) (T—i)
V ~ y>| (459+^0 (T—t).................... f29i
98
from whence results the following formuloe for determining the upcast
temperature T, and the ventilating pressure or head of air column
required to put the quantity Q in circulation, provided we have first
observed the quantity Q put into circulation by an observed upcast
average temperature T; representing such head of air column so required
to cause
the quantity Q to circulate by H— d ( -r^—r„ \ • viz :—
T- tQ2(459+T)+459g^T-t) nol
and
^-QH459+T) ................... ^1)
As an example illustrating the application of these formulae let us take
the case of Haswell colliery, already alluded to, where the average
upcast temperature, observed to create a ventilation of 94,900 cubic
feet per minute, was 105°, when the downcast shaft temperature was 62°,
and let it be required to determine the quantity of air which would be
put into circulation by raising the average upcast shaft temperature to
the high temperature of 369°8. Taking the formula [29], and having
Q=94,900, T=165°, t=62°, and T=369°*8, gives
0=94,900
(459+165) (3690-8-62) ^ ^
(459+369°*8) (165-62) '
feet per minute, as the quantity due to the average upcast temperature
of 369°*8 ; shewing that an increase of nearly 200 per cent, in the
excess of the upcast over the downcast shaft temperature only creates an
increase of about 50 per cent, in the quantity of air circulating in a
given time.
Had it been required to find, by calculation, the temperature of the
upcast shaft, which would produce a ventilation of 142,350 cubic feet
per minute, after observing that 94,900 cubic feet per minute resulted
from an upcast temperature of 165°, in the same time, where the downcast
temperature is taken at 62°; then, by [30], we should have had
T== 62 x 94900* (459 +165) +459 x 1423508 (165-62)_ orqo.o 949003
(459+165)-142350a (165-62) ;
as the average upcast temperature required, showing the mutual agreement
of the formuloe [29] and [30].
Again, when the temperature and corresponding ventilation or quantity of
air are given, and it is required to calculate the ventilating pressure
or height of an air-column due to any other amount of ventilation in the
same mine, then, by [31]
„_1423502x 936 (165-62) Qjl *.. lf --------94900^(^+165)
~347'6 lineal ieefc
99
height of air-column due to the ventilation of 142,350 cubic feet of air
per minute in the case of Haswell, as already alluded to; so that,
whilst a ventilating column of 154*5 feet high put 94,900 cubic feet of
air per minute into circulation, it would, in the same mine, require a
column 347*6 feet high, of the same density, to put 142,350 cubic feet
per minute into circulation—showing how slowly the quantity of air is
increased, as compared with the rate of increase of ventilating pressure
employed, being an increase of nearly 125 per cent, in the pressure to
produce only about 50 per cent, increase in the amount of ventilation,
the square root of the pressure increasing as rapidly as the quantity of
air put into circulation increases. When several calculations are to be
performed, the operations may be shortened by finding a constant C, for
any mine, by first observing* a series of corresponding values of Q, T
and t, and making
C=Q
T-t For, on substituting this value of Q
459+T .................. [32]
459 +T in [29] we get
T-t
Q=C
T~% ..................[33]
^^^^^^^^^^^^^ 459+I7 ^^^^^^^^^^^ And, by a similar substitution in [30],
there results
T 459^+C3t r341
c*—#a ................... J
The value of the constant C, as suited to any mine, can readily be found
by taking simultaneous values of Q, T, and t, and substituting them in
[32] j in the case of Haswell, which has been taken for a previous
example, Q = 94,900; T = 165°, and t = 62°, and, by [32] in this
instance,
C= 94,900
459 +16JL: 233,588.
^^^^^^^^^^^ I 165-62^^^^^^^^^^^^ By applying [33] to find the quantity
of air due to an unusually high upcast temperature, as before, 369°*8,
0=233,5*
369*8- 62 = 14o 350 cubic feet,
^^^^^^^^^^^^^ 459+369*8^^^^^^^^^ as before found. And, in the same
instance, by the application of [34], to find the temperature due to the
quantity 142,350 cubic feet of air
per minute,
T= 459 x 142,350*+ 233,588a x 62 = spqo R 233,588s-142,350*
'
shewing the agreement between [29] and [33], and also between [30] and
[34] respectively.
100
CHAPTER IV.
On the consumption of fuel by ventilating furnaces, and the method of
determining the comparative economy of different modes of ventilation.
(30.) In order to determine the comparative economy of fuel by different
modes of producing ventilation, it will be necessary to ascertain what
would be the consumption of fuel by each mode to effect a fixed or
standard amount of ventilation in one and the same mine 5 and when it is
not convenient to do this by experiment, it becomes necessary to
ascertain by calculation what would have been the consumption of fuel by
each mode had they been so applied; taking as data the results of their
application, under different circumstances, or at different mines.
We proceed to investigate formulae, which may serve to make such
comparisons. Let F = Sbs. of coal consumed per minute.
q = number of units of heat given out by each lb. of coal j that is to
say, = the number of "lbs. of water which each lb. of coal will, by its
combustion, raise through 1° of temperature, depending on the quality of
the coal. Q = the corresponding quantity of air put into circulation
each
minute, reckoned in cubic feet, w = the weight, in lbs. avoirdupois, of
a cubic foot of the air of
the density at which Q is determined. r == the temperature of the
return ah', before being influenced by
the heat of the furnace, t = the temperature of the downcast shaft,
taken where the average
heat prevails, if it is not uniform. T = The average temperature of the
upcast shaft. •2669 = The specific heat of air, when that of water is
assumed at unity as a standard; that is to say = the quantity of heat
required to raise 1 lb. of air, through the same number of degrees of
temperature, which an unit of heat would raise 1 lb. of water through.
101
Let F = Hhs. of coal required to be consumed per minute, t© cause a new
quantity of air, Q, to circulate through the same mine, when Tis taken
to represent the corresponding average upcast temperature. In the case
of ventilation by furnace action, the increase of temperature which
would be imparted to the air by the fuel would evidently be (if there
were no loss by cooling) expressed by
•2669 Qw.........................[35]
The real excess of temperature in the upcast shaft over that in the
downcast shaft, if there were no loss by cooling, would be
ssSV'-'...................|38]
And when the average prevailing temperature of the upcast shaft is
deducted from that which would have prevailed had there been no loss by
cooling, the result,
•^Vw + '-T..............'-W
is the loss of temperature by cooling, after passing the furnace, and
before reaching the point where the average temperature, T, prevails in
the upcast shaft.
(31.) According to Petit and Dulong, the velocity of cooling, or, in
other words, the reduction of temperature which a heated body undergoes
in an unit of time, supposing the excess of temperature of the heated
body, over that of the medium to which it is exposed, to remain
constant, and equal to T— t, by taking such unit of time as indefinitely
small; calling such velocity of cooling v, is
v = m (1-0077 CT_t)-l) + n (T-t) -1*233............[38]
That part of the velocity of cooling represented by m (1* 0077^-^-1),
being due to radiation alone; and the remaining part, represented by
n (T—t) ' being due to the contact of the gaseous medium to
which
the cooling body is exposed.
The coefficient m, depending for its value upon the nature and extent of
the surface of the heated body; while the value of n depends upon the
nature and pressure of the surrounding gaseous medium to which the
cooling body is exposed, and the extent of surface exposed to it by the
body.
The complexity of this expression is such as to render it almost
inad-Vol. III.—Dec, 1854. p
102
missable into any but very particular calculations, and for the present
object it would perhaps be useless to attempt its introduction, inasmuch
as it would probably prevent the formulae being made use of in cases
where more simple formulae, although mere approximations, would be
employed, as being less troublesome.
(32.) We shall probably obtain a tolerable degree of approximation to
the truth, if we presume that the reduction of temperature by the
cooling of the air, in ascending any upcast shaft, is directly
proportional to the prevailing average excess of temperature in the
upcast shaft, over the temperature of the downcast shaft, and to the
length of time which the air is exposed to the cooling influence of the
shaft walls.*
Now, since the time of exposure of the air to the cooling influence of
the shaft, just referred to, is, in the same shaft, always inversely
proportional to the quantity of air circulating in a given time, the
assumption we have adopted leads to the conclusion that the loss of
temperature by cooling, after passing the furnace, will, in the same
shaft, be proportional
X__t
*° —O—> so ^a^ we may a(^°P* a constant 1, suited to any shaft, of
such value, that
I—-*.......................[39]
will express the actual loss of temperature, whatever may be the values
of the variables T, t, and Q; and hence [37]
Q -2669 Qw +
so that by observing any corresponding values of F, Q, T, t, q, w, and
r, in any shaft, we can find 1; for, by the above,
1 = ^r{-26cFoC1Qw+r-T}..........[40]
* It is probable that this assumption is nearly correct, because,
according to Newton, if we let—for approximate rules—
A = initial temperature of a heated body; T == its temperature after the
time t; a = a constant coefficient;
V = the velocity of cooling- which will occur during1 the unit of time,
for an excess T of temperature of the body over that of the surrounding-
medium ; and supposing" this excess to remain constant, we have the
relations a t Log-. T = Log1. A — q7oq~ ; and V= a T.
By the former we can find the temperature T, after the time t, when we
know the value of a, which depends on the weig-ht of the body, and the
extent and nature of its envelope or containing- vessel, when it is a
liquid, which can be determined by a sing'le experiment. The second
gives the velocity of cooling-, when we know the excess of temperature
of the body over that of the medium to which it is exposed.
108
T—~t And the difference, found by deducting the loss by cooling, 1 —jj—,
from
the excess of temperature [36], which would have prevailed, if there had
been no cooling, will give the prevailing excess of temperature, as due
to the assumed consumption of fuel F, and its corresponding air Q; or
and hence
Fm 'M^SQ(T_r)+HT__t)\ ................[42]
in which equation the value of T—t can first be determined from [30], or
[34], as due to the quantity of air Q; by means of any observed
corresponding values of T, t, and Q in the same shaft: and from this
equation [42] itself, the quantity of fuel F, required to be consumed
per minute, to cause the assumed quantity of air Q, to circulate in the
same mine, can be found.
These formulae, as already stated, are based upon the assumption of the
loss of temperature hj cooling, being proportional to the prevailing
excess of the temperature of the upcast, over that of the downcast air;
and, inversely, to the quantity of cool air circulating in a given time:
it is, however, probable that the loss by cooling increases in a ratio
somewhat higher than that of the simple excess of temperature -, and, in
fact, the time of the air being exposed to the walls of the shaft, will
not be precisely inversely proportional to the cool air circulating, but
rather to the expanded volume of heated air passing up the shaft in a
given time, considerations indicating that the formulas just given, are
not to be regarded as affording more than near approximations to the
truth, but as they may be serviceable in making comparisons and
calculations on the subject, and may even lead to more simple and
trustworthy rules, it has been considered proper to present them.
[33]. Before applying the preceding formulae to examples, it will be
proper to give rules for finding the weight, in lbs. avoirdupoise, of a
cubic foot of air, or the value of w. Dr. Prout determined the weight of
dry air at the temperature of 60° Fahrenheit, and under a pressure of 30
inches of mercury, to be 535-882176 troy grains, or -0765546 lbs.
avoirdupoise, per cubic foot; and since the density of air is inversely
proportional to the sum of the temperature, and the constant number 459,
when the pressure remains constant j and again, directly proportional to
the pressure under which it exists, when the temperature is constant; if
we
104
express the temperature of the air by t, and the pressure in inches of
mercury (reduced to 60°) by f, we get the proportion,
. 30 mnrrAn.. f 1'3244 f
As "459+60- : '°76°546 • • 459+t ' 459+t and hence
1-3244 f ..„
w= -459+r....................W
When, however, the air contains any vapour of water, the mixture will be
of less density than is due to dry air at the same temperature, because
the specific gravity of vapour of water, at the same temperature and
pressure as dry air, has been found to be less than that of the air.
Taking the average of the various slightly differing statements, as
regards the specific gravity of vapour of water, we shall find that it
is about -622, that of air at the same temperature and density being
assumed at unity as a standard.
Now, in order to find the weight of a cubic foot of any gas or vapour,
we have only to ascertain by [43J the weight of a cubic foot of air at
the same temperature and pressure, and multiply the result by the
specific gravity of the gas or vapour in question. So that if w' express
the weight of a cubic foot of any gas or vapour, of which the specific
gravity is s, we have, , 1-3244 f
rAAi
W = 459+t X S.............[U]
Dalton discovered, that, although evaporation takes place more slowly
from the surface of a liquid exposed to air or gas, than in a vacuum,
yet any given space will admit the self-same quantity of vapour, whether
such space be previously filled with air or gas, or whether it be a
perfect vacuum; so that when a vapour is generated within a vessel which
does not yield to pressure, if it is previously occupied by air or gas,
the vapour generated, and the air or gas coexist throughout the entire
extent of the vessel, and each exerts its own pressure or elastic force
against the sides of the vessel, just as if the other were not present;
and hence, the pressure on each unit of surface becomes equal to the sum
of the pressure exerted by the air or gas, and that exerted by the
vapour. When there is present an excess of the liquid, which gives off
the vapour, evaporation goes on till the pressure and density of the
vapour become equal to those which are due to the temperature when the
vapour is in a state of saturation, and then it ceases. If, for example,
the tension of the air or gas = f, and that of the vapour = f', the
tension or pressure of the mixture will be f + f'.
105
If, however, the sides of the vessel are perfectly yielding under the
outward pressure of f, then the mixed air and vapour expand in the ratio
off to f + f', and thereby the pressure of the mixture is reduced to the
original pressure of the air f; and hence, in this state of the mixture
the
elastic force exerted by the air or gas becomes f ,„ , j f, and
that of the
vapour (—7T77~ jf'- Now, since, by expansion, the space has been
enlarged, a fresh portion of the liquid is converted into vapour, so as
to fill it, with the elasticity f, due to the temperature, giving rise
to a further expansion, which, in fact, goes on continuously, till the
volume of the mixture, is to the original space, in the ratio of f to
f—f'; because, after complete expansion under the pressure f, the vapour
has its full elasticity f', so that the pressure of the air or gas can
only be f—f', in order that their sum may be equal to f, the total
pressure; and the space occupied by the air, (and penetrated by the gas
also), will be inversely proportional to the elastic force of the air
before and after expansion, respectively; or as f—f' is to f.
Now, in order to find the elastic force of the vapour of water, mixed
with air, it is merely necessary to introduce a vessel into the mixed
air and vapour, and to reduce its temperature, by any of the known
means, below that at which some of the vapour begins to condense upon
the vessel, or what is called the dew point of temperature, and
carefully to note the temperature at which such dew or condensed vapour
evaporates, as the temperature of the cold vessel returns towards that
of the mixed air and vapour j then the elastic force due to the vapour,
contained in such mixture, will be found by a reference to a table of
the elastic force of vapour of water, as due to different temperatures
when the vapour is saturated; using, in referring to such table, the dew
point of temperature, observed as already stated; for the vapour in the
air would evidently be saturated vapour at that temperature, seeing that
it is partially condensed by the slightest further reduction of
temperature—then, having determined thus, the elastic force f, and noted
the actual temperature of the mixed air and vapour t, we will have by
[39], the weight of vapour in each foot of the mixture. In order to
obtain the weight of air in each foot of the mixture, we will only have
to deduct the tenison f of the vapour from the total barometrical
pressure, to obtain the actual pressure under which the air exists in
the mixture, and by using the pressure so found, as the tension or
elastic force, and the actual temperature of the mixture in [43], we
obtain the weight of air in each cubic foot. Tredgold has given a
106
formula, which, being* used instead of reference to tables, may be
relied upon as giving- very accurate results in determining- the elastic
force of the vapour in the air, in inches of mercury. If t° be the
observed dew point then
M^y.......................m
(34.) Before returning to the general formulas an example will here be
given of the application of those just mentioned, by which to determine
the value of w.
Let it be supposed that in a mixture of air and vapour, at a temperature
of 201°, the dew point were noted at 176°, the barometrical pressure
being 30 inches, then, in order to determine the weight of air in each
cubic foot of space, on referring to Dalton's table hereinafter given,
we would find the tension of saturated vapour, at a temperature of 176°,
as being 13'92 inches of mercury=f, and consequently (30—13-92=) 16"08
is the tension of the air with which it is mixed, under the general
atmospheric pressure of 30 inches of mercury. Now, by [43] the weight of
air only in each cubic foot, is
1-3244 x 16-08 rtQrtftan( - . , -.
w= '—4.5Q4- on to" ='032267 lbs. avoirdupoise.
The weight of vapour in each cubic foot of the mixture, by [44], is
, 1-3244x13-92 ._0 m»Q„A1h w "" 459 + 201 x "622
=-017374 fcs.
And the weight of a cubic foot of the mixture consequently is -032,267 +
•017,374=-049,641 lbs. avoirdupoise.
The weight of a cubic foot of dry air, at the same pressure and
temperature as those of the mixture, would, by [43], have been, -i
.3944 x 30 459 + 201' = 'Q62Q2fe-- showing that the mixture is lighter
than
dry air.
The tension of vapour of water at 176°, as given by Tredgold's formula,
is 14-37, which, it will be seen, agrees very nearly with Dalton's
table. The use of the formula in this case being as follows:—
176° + 100 = 276, the log. of which is..........2-4409091
177, a constant number, the log. being.......... 2-2479733
Difference .......... 0-1929358
Index, or constant multiplier...... 6
14*37= the natural number of the product----- 1-1576148
107
(35.) When any large proportion of vapour of water is present in air,
instead of using -2669, the specific heat of air, and w as determined by
[43], in order to obtain the unities of heat required to raise a cubic
foot through a degree of temperature, it will be necessary to find the
weight of air and the weight of vapour in each cubic foot of space, as
just shown, and to multiply the weight of air by -2669, and that of the
vapour by •847—the specific heats of dry air and of vapour of water
respectively,— and to make use of the sum of the products in lieu of
using "2669 w, in [35], [36], [37], [40], [41], or [42], or any others
into which these quantities enter, as they can only apply to dry air,
although where the vapour is of low tension no great error will arise
from taking the formulas as they stand.
In mines the air is often in a state of saturation with vapour before
reaching the furnace, and if we take the tension due to 61° it is
•524=f/;
and if the barometer stood at 30 inches, the tension of the air would be
30—-524=29-476 • the weight of air in each cubic foot being by [43],
1-3244x29-476 MKMa-
w = 459 + 61° ='07507S ft*-
The weight of vapour in each cubic foot being, by [44], i .3044 x .504
w'= 46Q +*610 x -622 = -000,830 lbs.
and the weight of a cubic foot of the mixture would be "075073 + •000830
= -075903 lbs., the weight of a cubic foot of dry air being ¦076408
lbs., so that the error in weight, when the vapour only has a tension
due to 61°, under a pressure of 30 inches, would never exceed about
2-3rds per cent., whatever might be the actual temperature of the
mixture, as the air and vapour expand alike. The specific heat of the
mixture would require to be taken as
•075073 x -2669 + "00083 x -847
•076408 —-2714,
that of dry air being -2669, so that the error here ag'ain would only be
If per cent.
(36.) To give an example illustrating the application of the formulae at
the commencement of this Chapter, let it be presumed that in the case of
Haswell colliery, as already alluded to, there was burnt 17-3212 lbs. of
coal per minute, when 94,900 cubic feet of air was circulating, and that
the quality of the coal was such as to give out 13,800 unities of heat
per lb. of coal, over and beyond all waste of combustible and other
matter in the cinders, soot, and smoke • that is to say, supposing each
lb. of coal put into the furnace to give out sufficient heat in
combustion, as it
108
occurred, to raise 13,800 lbs. of water through 1° of temperature, then
by [37], the loss by cooling would be 17-3212 x 13,800 •2669 x 94,900 x
-07626 + G7 ~ 1G^°= 25°-75,
when the weight w of a cubic foot of air is taken at -07626 lbs.
And since (165°—62°)=103° was the prevailing excess of temperature, it
follows that the initial excess of temperature must have been (103 +
25-75)=128°75, and that the loss has been (^ tockV— ) =• 20 per cent.
/25'75xl00\ of such initial excess, which is equal to f — --^— J =.25
per cent.
of the prevailing excess of temperature.
In the same case the value of the constant 1 will be found by the use
of [40], to be
94900 1 =^5^. x25°-75= 23,725.
Taking this value of 1, and, by [39], we can find the loss by cooling
when the larger quantity, or 142,350 cubic feet per minute are
circulating; thus,
— CSSF)-"8*
it being, in this instance, only 16 2-3ds per cent, of the initial
excess of temperature. And although this is a smaller per centage of the
initial . excess of temperature than was found to prevail when the
lesser quantity of air was circulating—owing to the greater quantity of
air being a shorter time exposed to the cooling influence of the shaft
walls—yet since the actual quantity of air losing the temperature, and
also the actual reduction of temperature, are both increased, in the
case of the greater circulation of air, we find that the real loss of
caloric is very much greater also, it being, in the two cases,
proportional to the products 142,350 x 51°-3 and 94,900 x 250,75, or
nearly 3 to 1, although the quantities of air are only in the ratio of
about 1| to 1.
By [42] we find that the consumption of coal required to put 142,350
cubic feet of air per minute into circulation, would be, using [30] or
[34] to find T= 369°-8 ; F= -^^^^- j 142350 x (369°-8-67°) +23,725 x
(369°-8—62°) I =74-345 lbs. per minute, being 4-29 times the quantity of
coal required to put the lesser quantity, (or about f rds of the
quantity,) of air into circulation in the same unaltered mine, in an
equal time. Each lb. of coal, when the lesser quantity of air is
circulating,
therefore, puts -,7.Q010 = 5,479 cubic feet of air into circulation;
but
109
so enormous must be the increase in the consumption of fuel, to put \\
times this quantity of air into circulation, that it will be increased
4-29
142350 times—each lb. of coal then putting only 74^45— = 1>914 CUDic
?eet
of air per minute into circulation, in the same unaltered mine.
The quantity of air put into circulation in a given time, in the same
mine, therefore, increases very slowly compared with the necessary
accompanying increase of fuel, consumed; there being in fact no increase
in the ventilating pressure, where furnace action is employed, produced
by that part of the fuel required to heat the additional air up to the
original shaft temperature; while the remainder of the additional fuel,
only adds to the quantity of air put into circulation, in a ratio
proportional to the square root of the entire pressure produced; so
that, on the whole, the consumption of fuel required for the production
of ventilation, by furnace action, increases in a ratio somewhat higher
than even the cube of the quantity of air put into circulation in a
given time.
If we now presume that the question had been to determine what the
consumption of fuel would have been, in the same instance as that
already taken, to produce an upcast shaft average temperature of 3690,8;
we should in the first place require to determine the quantity of air Q,
which would be put into circulation, in the case in question, by such an
upcast temperature; and this could readily be found; for, by [32] we
should find the value of C = 233,588; and then by [33] we should find
the value of Q = 142,350 : and then, on substituting these values of T
and Q, in [42], we should, as before, have found
p_ -2669x^07626 ^ 142350 (369°-8—G7U) +23725 (369° 8-62) 1 = 74-345
lbs.
for the consumption of fuel per minute :' the value of 1, in each
instance, being found by [40].
If, however, it had been required to determine by calculation, the
quantity of air Q, due to some assumed consumption of fuel F} the case
becomes more intricate, requiring the solution of a cubic equation, with
very troublesome coefficients; and in preference to this mode, it might
be better to assume a value of Q, and by proceeding, as has been
indicated, for the case of the quantity of air being given, find out the
corresponding consumption of fuel; repeating the process, on the
principle of double position, until the actual quantity of air is found,
to the degree of nicety considered desirable.
A similar remark will apply to the case of the upcast average
tempera-Vol. HI.—Dec, 1854. Q
110
ture requiring to be determined, when only the consumption of fuel is
given, or assumed.
(37.) When ventilation is created by engine power applied through
machinery, the consumption of fuel may be taken to be proportional to
the power exerted by the same machine. The entire pressure per unit of
surface may be taken, as already stated, as being proportional to the
square of the volume of air circulating through the workings of the
mine, which we will presume to be the same as the volume passing through
the machine, for even 5 inches of water pressure is not more than
one-eightieth part of the entire pressure of the atmosphere, and on the
average, in mines, the expansion or condension will alter the volume of
the air, in a machine, only about one-half of this amount, from the
average volume of air in the workings.
If A represent the area of the upcast shaft, and Q the cubic feet of air
circulating per minute, then will —t— be the velocity of the air in the
shaft in feet per minute• then, if p represent the pressure in lbs. per
su perficial foot of shaft area, required to move the air through the
mine, we shall have p A for the entire pressure exerted over the total
area of the
shaft, for this purpose; and consequently —-r— x p A -r- 33000 will be
the horses' power exerted in moving the air up to the mouth of the
upcast
Q p shaft, which is expressed by*ljq~/wr; reasoning in a similar manner
with
regard to the power required to draw the air into the ventilating
machine, when it acts by propulsion, or to expel the air into the
atmosphere, when the machine acts by exhaustion, and calling the area of
the opening from the machine to the atmosphere, a, and the pressure
required, p', we shall
Qp'
have the horses' power expended upon this, expressed by -q'o nfin >anc^
consequently, the entire power will be expressed by their sum, or
1I=Z Q(p + p') ...............r46]
33,000 ...................L J
where II is the number of horses' power exerted.
But, since the squares of the quantities are proportional to the
pressures
per unit of surface, under similar conditions p + p' will be
proportional to
Q1, and therefore a constant, c, may be adopted for any given case, of
such a value that
p + p'=cQ2........................[47]
whatever may be the quantity of air circulating, or its corresponding
111
pressures p and p', in the same machine, and unaltered mine • by
substituting which value of p -f p' in [46], wo obtain
^wm.....•..................m
and since c, and 33,000, are both constants in any one case, we perceive
that iToc Q3; and since the power is proportional to the cube of the
quantity of air circulating in any given mine, by the same machine, and
the consumption of fuel is proportional to the power exerted, it follows
that, under the same circumstances, the consumption of fuel by an engine
employed in ventilation, will also be proportional to be cube of the
quantity of air put into circulation in a given time.
The value of c, as suited to any particular case, where a ventilating
machine is already at work, will be found by observing
corresponding-values of p, p', and Q• and using the following formula,
which is deduced from [47]
— -*$£-......................m
after which, the quantity of air which will be put into circulation in
the same case, by any power whatever, may be found by the following
formula, arising from [48],
Q = SWMR....................[50|
N C
while the*power due to any other assumed quantity of air, can be found
by [48] itself.
The consumption of fuel by the engine, expressed in lbs., per horse
power, per hour, being denoted by f • and the entire consumption, in
lbs.
ill F60-
per minute being denoted by F, gives- ff)~=F; and hence, H=—7—-
which value of II being substituted in [46], gives
60 J1 Q (p+p')
f "" 33,000 and in [48], gives
60 F _ cQ3
f ~ 33,000 ...................' J
From whence
c f
Fss 1,080,000 Q3..................^
by which the consumption of fuel can be found, whatever may be the
quantity of air circulating; and
112
1,980,000 ~
' by which the quantity of air due to any consumption of fuel whatever
may be found.
As an example, illustrating the application of these formulae, let it be
required to find the comparative economy of fuel, between the use of
ventilating furnaces, and an exhausting ventilating machine, of the
description used in the Hartz mines, called the Hartz ventilator, if
applied to the case of Haswell Colliery, on the data already given.
When 94,900 cubic feet of air per minute was put into circulation by
furnace action, we have presumed the consumption of fuel to have been
17*3212 lbs. of coal per minute, which is probably close upon the real
consumption. The head of air column, due to the ventilating pressure, we
have determined to be 154-5 feet• and supposing the density of the air
to have been .0757 lbs. per foot, the temperature at which the height of
the column is calculated being 62°, and the air is presumed to have been
nearly saturated with vapour due to that temperature, then the
ventilating pressure would be 154-5 x 0757=11-69565 lbs. per foot, = p
in our formula; and if we presume, the pressure required to expel the
air from the receiver of the ventilating machine to be 5-30435 lbs. per
foot, we should have this, for the value of p', and p + p'= 17 lbs. per
foot; and, by [46], the horse power required
94,900x17 _ 48.89 M--------3p00-------^ ™
By [49] we should have, in this case, the value of
c= q^Joq, « .000,000,001,887
and if we take the consumption of fuel, by the engine, at 12 lbs. per
horse
power per hour, we should have, by [52],
F- -000,000,001,887x12 g _ g<78 ft
1- 1,980,000 xv*,vw-vfoiu.
for the consumption of fuel per minute by such an engine working the
ventilating machine, when 94,900 cubic feet of air per minute was
circulating, as compared with the assumed consumption of 17*3212lbs. of
coal per minute by furnace action to create the same amount of
ventilation, the pit being 150 fathoms deep. In pits of greater depth
the furnace will operate more economically, and in others of less depth
its consumption of fuel would be greater, other things being constant.
All the formulae given in this Chapter are based upon the presumption
118
of there being no natural sources of ventilating pressure in the mines
to which they are applied, and they can only be strictly considered as
applying where this is so; at the same time in deep shafts, and where
the inclination of the mines is moderate, and a tolerably active
ventilation is kept up by artificial means, they will form good
approximate rules, although the tops and bottoms of the downcast and
upcast shafts do not happen to be situated in the same horizontal
planes, and there be some sources of natural ventilation arising from
the air in the ascending parts of workings being rather warmer than in
descending parts, or the reverse, so long as such causes operate to a
small amount in comparison with the applied ventilating power.
In shallow pits, and where mines lie at a considerable degree of
inclination to the horizon, particularly when the ventilating power in
use is small, the formulae given will not apply; natural ventilation, in
such cases, often forming a large proportion of the whole ventilating
power in operation.
114
CHAPTER V.
On the circulation of air through long galleries er air mays—the
benefits of "splitting" the air in mines.
(38.) A perusal of the laws recited in Chapter I. lead to the conclusion
that the entire pressure per unit of surface required to overcome the
various resistances to the circulation of air in confined passages, will
be proportional to the square of the quantity of air circulating- per
minute, so long as the form, nature, and dimensions of the air ways
remain unaltered; because the pressure due to each kind of resistance
follows the law of variation just named; and, therefore, the sum of all
these pressures must vary in the same proportion.
When, however, the axis of a gallery or air way is not situated in the
same horizontal plane, throughout its whole extent, but ascends or
descends to different elevations or levels in its course; it becomes
necessary to consider the effects of the ascending and descending
columns of air in such parts, which will, by their gravitation,
necessarily affect the circulation of the air—excepting, indeed, in
cases where the effects of the gravitation of the air in the ascending
parts are exactly equal to, and so counteract the effects of,
gravitation on the descending parts—as any excess of the one over the
other will represent a constant pressure, either in favor of, and
assisting- ventilation; or retarding it, as the case may be; but being
invariable in amount, so long as the temperatures of the air remain the
same, whatever may be the quantity of air in circulation.
(39.) Again, if the final or exit end of an air way, such as the top of
an upcast pit, when we are considering the entire mine as the air way,
be situated at a higher level than the initial or entrance end of the
air way, (the top of the downcast shaft, under such circumstances;) so
that the barometrical compression of the atmosphere is not the same at
these two points; it becomes necessary in considering the dynamical
state of the
115
entire system to make allowances for any difference of pressure arising
from this cause ; which, like the pressures last alluded to (38),
remains constant; or may in general be regarded as doing so, in the same
mine, whatever may be the quantity of air circulating in a given time.
(40.) It may further be observed that the pressure per unit of surface,
due to the generation of any velocity possessed by a current of air,
when it first reaches the initial or entrance end of an air way under
notice, will act as momentum and assist in propelling the air through
the air way j so that it may be regarded as so much ventilating-
pressure assisting the other sources of ventilating pressure in causing
the air to circulate ; and, on the other hand, any pressure due to the
generation of the final velocity with which the air is ejected from the
exit end of the air way under notice, will be carried off as momentum by
the ejected air, and will be a constant source of expenditure of
ventilating pressure : these pressures, however, are proportional to the
square of the quantity of air circulating in a given time in the same
mine.
The air, entering the top of a downcast shaft from a state of rest, must
not be regarded as reaching the entrance end of the air way with a
positive velocity, because, in fact, it starts from a state of repose
when we disregard the effects of winds, which we are not here
considering—but the pressure due to the generation of the velocity with
which the air leaves the top of an upcast pit, or the exit end of an air
way or gallery, or any particular portion of an air way under notice,
will always require to be considered as a real expenditure of pressure,
over and beyond the amount due to the frictional and other resistances,
offered by the passage or air way. When, however, we are confining our
notice and observations to only some limited portion of an air way, or
series of air ways, where the air actually reaches and enters upon such
portion with a real velocity, it becomes necessary to consider the
effects of momentum, as possessed by the air when it so enters ; because
the pressure due to the generation of the velocity in question is, in
fact, so much pressure assisting- any other sources of ventilating
pressure in propelling the air through the air w;iy, and finally
ejecting it therefrom.
(41.) In order to enter upon the investigation of this part of our
subject, let us take a case where we will suppose that the tops of the
downcast • and upcast pits are situated at the same level, each of the
same depth, and that the gravitation of the air in all the ascending
parts of the air ways (the shafts only excepted) exactly equals and
counteracts the gravitation of the air in all the descending parts of
the air ways; under which circumstances no natural ventilation would
prevail.
116
Then, if D0=The pressure per superficial foot (expressed in feet of air
column, of
the density due to the air in the downcast shaft) arising from the air
in the downcast shaft, being in fact the depth of the downcast shaft
itself in lineal feet. U0=The pressure per superficial foot, (also
expressed in feet of air column,
of the density of the air in the downcast shaft), due to the air in the
upcast shaft. R=The pressure per superficial foot, (also expressed in
the same terms as
D0 and TJ0), required to overcome the frictional resistance offered
by the shafts and air-ways when only one cubic foot of air per minute
is in circulation. A=The area in feet of the top of the upcast shaft.
Q=The number of cubic feet of air circulating per minute.
Under the circumstances just supposed, we would have for the entire
ventilating pressure employed D0—U0; and the portion of this pressure
employed on overcoming the frictional resistances of the shafts and
airways would be expressed by Q2R; the remaining part of the ventilating
pressure employed would be expended on the expulsion of the air from the
top of the upcast shaft, (presuming that Peclet's experiments are
correct in leading to the conclusion that angles and turnings do not
increase the resistance of an air-way; or on the other hand that R
includes any such resistances, as due to the mine, if they exist), where
the velocity
would be -r- expressed in lineal feet per minute, and the pressure due
to
its generation, as deduced from [10], would be •tt:.^ . 8 ¦¦; giving,
therefore,
j0-g0^<yR+ S31g0A, ...............[54]
which may be reduced to
i».-d>v(*+«jw7F)............m
and gives rise to the equations,
<H ^0~T° :....................m
**R+ 231,600 A2 and
R — D°~ U°___.___--------.......... T571
u~ Q'! 231,600 A2 L J
117
And if we presume furnace ventilation to be the means used to cause the
air to circulate, by referring to [22] we perceive that,
^-^ = dhwr*................[58]
and, by substitution,
Q= * 469+T-l......................[69]
4 R + "231,600 A2 and,
R_ dl"459 + T 1________!___.:......[eo]
""" Q3 231,600 A2 L
J
On comparing equations [59] and [33], it will be seen that they are of
the same form, and, in fact, that,
0=] df—....................[613
JR + 231,600 A2"
So that if we had the means of determining the pressure per unit of
surface R, required for circulating one cubic foot of air per minute,
by-measuring the dimensions of the air-ways, contractions, &c, in such a
mine; we could, by [61], determine the value of the constant C; and
then, by [34] we should be able to determine the upcast temperature
required to circulate any quantity of air in the mine; or, by [33], we
could find the quantity of air which would be put into circulation in
the mine by any assumed upcast shaft temperature, and that without any
previous observations on corresponding or simultaneous upcast shaft
temperatures and quantities of air.
(42.) To determine the value of R, or the pressure per unit of surface
due to the resistances arising from friction, contractions, &c, in a
mine, by means of measurements and observations on the resistance
offered by different materials, composing the inner surfaces of the
air-ways, as due to the circulation of one cubic foot of air per minute,
would generally be an extremely troublesome operation, and in extensive
mines where the air is subject to great losses by the leakage of
stoppings and doors, and often has the chance of passing through
galleries and goaves, so filled with fallen stones and other materials
as to render them inaccessible, it would be useless to attempt such a
task; at the same time, for many purposes other than the ventilation of
mines, such as the transmis-Vol. III., Dec, 1854.
&
118
sion of air or gases through pipes, flues, or chimneys, it may be useful
to be able to determine in this manner, the pressure in question; and
hence we shall not think it a waste of time to give formulse bearing
upon the subject, more particularly as they may, if used in conjunction
with other means, to be explained in a future page, be found useful in
considering the ventilation of the most extensive and complicated mines.
(43). In order to find the value of R by means of measurements, and
observations on the nature of the materials forming the internal walls
of an air-way, pipe, or flue, it will be desirable, in the first place,
to consider it as divided into such short lengths as may be necessary,
in order that the area and perimeter of section, and also the nature and
state of the material composing the inner surface may be uniform
throughout the entire extent of each division, or, where, from the
tapering nature of the air-way, pipe, or flue, this uniformity of
section does not extend over any definite distance, other divisions
should be made, so that uniformly tapering frustra of cones or pyramids
be formed of the tapering portions.
If, then, L=The length in feet of any such division.
c=The perimeter of the section of the same uniform division, in lineal
feet. A=The area of the section, over the extent of the same division,
in
superficial feet. K=The co-efficient of frictional resistance due to the
nature of the material forming the internal walls of the air-way, being
the pressure required to overcome the frictional resistance offered to
the air when moving at the rate of one foot per second, for each
superficial foot of rubbing surface exposed to the moving air. Then, by
(5), (6), (7), and (8), we have, for the pressure per unit of surface
required to overcome the friction of a cubic foot of air per minute,
passing through the division under consideration alone,
K^J-.........................[62]
and since this pressure is proportional to the square of the quantity of
air circulating in a given time,
K-^^...................... .-[63]
will be the pressure per unit of surface required to overcome the
frictional resistances of the same division, when any other quantity of
air, Q, is in circulation through it, per minute.
By applying [62] with different values of K, L, c, and A, as suited to
each separate division, we shall successively obtain the amount of
pressure
119
required to overcome the frictional resistances of each of them, as due
to one cubic foot of air per minute passing through each.
Referring to (14), and considering that the quantity divided by the
area, gives the velocity, we find that the pressure required to overcome
the additional resistance arising at each diaphragm or regulator, when
only one cubic foot of air per minute is passing, will be expressed by
a | -^ jr~ (....................[64J
A ) 231,600 J
a being the area of the hole in the diaphragm, and A that of the airway
in feet. A little more than one-half of this amount being, probably, the
pressure due to each sudden contraction of the air-way in the direction
of the current of air; but, as to which, further experiments appear to
be desirable, as also with respect to the above empirical formula, which
does not give precisely correct results.
For each conical part of the air-way, the pressure per unit of surface,
due to one cubic foot of air per minute passing, will be found by the
expression
__^Kd)___.................m
d (m—1) m4 A8 Cos u L J
where L is the length of the frustrum, in feet; A the area in feet of
the smaller end of the frustrum; m, the ratio of the greater to the
lesser diameter of the frustrum at its extremities j d being the lesser
diameter in feet; and u the ratio of the area of the contracted vein to
that of the full area of the frustrum, when the conditions are such that
a contraction of the flowing vein of air occurs at the end of the
frustrum where the air enters it. But when m exceeds 2 or 3, and the
cone is long in proportion to its diameters, we may employ, as
sufficiently correct, the expression
d (m—1) A* ....................^
It results from the fact that the ratio of the perimeter to the area, is
the same in a square as its inscribed circle, that the resistance is the
same in the two figures alluded to when the velocities are equal • but,
for equal quantities of air in a given time, the velocities will be
inversely proportional to the areas, and the resistances inversely
proportional to the squares of the areas, (being directly proportional
to the squares of the velocities,) so that, in order to find the
resistance due to one cubic foot of air per minute, passing through a
four-sided pyramid, it will only be necessary to employ [65] or [66] to
determine the pressure due to a cubic foot of air per minute, in passing
through the inscribed cone, and
190
the pressure so found, on being multiplied by the square of 7854 or
'6168, will give the pressure required to circulate one cubic foot of
air per minute through the four-sided frustrum.
After having, by the means just mentioned, obtained the amount of
pressure per foot area, required to overcome the frictional resistance,
and the contractions, in each of the divisions or short lengths into
which it has been necessary to divide the air-way, it only remains to
add the whole of them together to obtain the entire pressure due to such
resistances, when one cubic foot of air is circulating through the
air-way; and this is, in fact, the value of R in the preceding formula?;
and since the pressure required is proportional to the square of the
quantity of air circulating in a given time, when the air way remains
unaltered, it follows that Q3 R will be the pressure per foot area,
required to overcome these resistances when the quantity Q is in
circulation.
(44.) If the air, instead of being confined to one single pipe, flue, or
air way, situated in a horizontal plane, had the option of dividing
itself into various splits by following different passages, situated in
the same plane, instead of using the value of R, as due to any
particular route taken by the air, it would be necessary to find the
value of R, as the pressure due to the resistances indicated by it, in
an imaginary passage, which should present exactly the same amount of
resistances as the joint action of all the united passages would, in
fact, present, when considered as aiding each other in transmitting one
cubic foot of air per minute; and the value of R so found, could then be
used in any of the formula already given, so as to give correct results
into whatsoever number of splits the air mightbe divided.
If, for instance, at any particular part, the air-way divided so as to
present two distinct routes to the air, a portion following each of the
ways so presented; and if we had found the pressure required to overcome
the frictional resistances, contractions, and angles, and to generate
the final velocity occurring in one of the routes, by [55], on the
presumption of one cubic foot of air per minute passing through it, and
represented that pressure by Mi. And if the pressure due to the
transmission of one cubic foot of air per minute were found by [55], for
the other of the two routes, and represented by Ma—excluding in each
case, any pressure due to the parts of the air-way, traversed by the air
before reaching, or after leaving the divided passages. If we further
represented by M the pressure per unit of surface required to transmit
only one cubic foot per minute through the two routes jointly, Qx
representing the quantity going by the route to which Mx has reference;
and consequently (1—Qv) going by the route to which Ms has reference.
121
The pressures M, Mw and M2, in each case, being understood to embrace
the pressure due to the generation of any initial velocity which the air
may possess on its arrival at the entrance end of the divided air-ways,
immediately before being split or divided; as any such pressure, in the
form of momentum, actually assists in the transmission of the air
through the splits. Then if the air-ways are either situated in the same
horizontal plane over their entire length, or, on the other hand, the
density of the air is so uniform that the gravitation of the air in the
ascents and descents in each particular route exactly counteract each
others effects, it follows that the air will naturally so divide itself,
between the two routes, that the expenditure of pressure in each
instance, including that due to the generation of their respective final
velocities, shall be of equal amount, or so that
M = Q« Ma = (1 — QO* M,................. [67]
and hence,
AsQi:(l —QO :: VMT: VH7 and also,
AsQx : 1 :: vMT: VMT+ VM7~
and therefore,
Q1==-----~-/M,!___ ...................[68]
and by substituting this value of Qx in [67], we get,
M =--------4^------.................[69]
as the pressure, which is just capable of transmitting one cubic foot of
air per minute through an air-way, which, alone, would present equal
facilities for the transmission of air with those offered by the two
air-ways acting in aid of each other; or, what is the same, the pressure
per unit of surface capable of transmitting a cubic foot of air per
minute through the two air-ways, considered jointly.
It must here be noticed that M, Mx, and M2, in the above formulas,
embrace the effects of the initial and final velocities, and so
represent the portion of JDQ~ U0, expended upon the divided parts of the
air-ways, when one cubic foot of air per minute only is in circulation
(and Q2 M, Q3 Mx, and Q2 M2 the portion when any quantity, Q, is
circulating, as in [55] j) and hence have a different signification from
R, in that formula; being, in
fact, the same as R + in that formula, when the
air
2dl,600 Aa ;
starts from a state of rest.
m
(45.) If instead of the air-way being divided into only two, it were at
the same place, divided into any greater number of ways or branches-, we
could find the joint effect or value of M, as due to the whole of them,
on the same principles; for, taking any two of them, we could find, by
[69] a value of M as suited to them, acting jointly, one in aid of the
other; and then, by adopting M, so found, and substituting it in [69]
for M1} and using M3, as the pressure due to one cubic foot per minute
being sent through the third route, instead of M2 in the same formula,
we would find the pressure required to send a cubic foot of air per
minute through such three routes, when acting jointly; and so on, for
any number of routes into which the air-way might diverge.
(46.) Although, in order to arrive at the quantity of air which will
pursue each separate route, where the air is split, it has been
necessary to consider the entire resistance, including that due to the
final velocity at the end of each split, and also to include in the
force or pressure employed that which is due to the velocity with which
the air reaches the point where it is split or divided, it will not be
necessary to consider these pressures at the commencement and
termination of each of the minor, or ordinary divisions into which the
air-way may be considered as divided, for finding the pressure due to
the whole air-way, because the final velocity of the air at the end of
each of such divisions will necessarily be the initial velocity of the
succeeding division, and so its effects would be continually
counteracted in adding the total resistances together, to obtain the
resistance of the entire passage or air-way.
(47.) In order to find the quantities of air Q1; Q2, Q3, &c, which would
pursue particular routes into which an air-way may be divided, the
specific resistances of which are Ma, M2, M3, &c, when M is the specific
resistance, found by the rules already given, as due to the joint and
united operation of the whole of them; when the entire quantity of air
transmitted through them is Q (always presuming the point where they
divide and re-unite, each to the parent current, is the same) and they
are not affected by the gravitation of the air in the ascending and
descending parts of the routes, we have only to consider that
Ql Mi = Qa M2 = Qt M3, &c, and that, therefore,. Qx VM^ = Qa VM^ = Q3
>/MT = Q VlTand hence
Q. = Q ^iQ2 = Qj^;Q3=Qjfr;&c.;....[70] for any number of routes so
circumstanced.
123
If, on the other hand, we had determined the specific resistance to
which the joint action of any number of routes so situated are
equivalent, to be M, and had observed the quantities of air flowing
through the various routes to be Q1; Q2, Q8, &c, we could thereby
determine the specific resistance of each particular route, because, by
[70], we obtain,
M' = (l-)'11' *-(-$-)'"« M-= (-$-)' ***...mi
where Qi + Qa + Qs, &c =Q, the entire quantity of air in. circulation
per minute.
In 167^\, [68], [69], U°l and [71], it must be borne in mind that the
pressures M, M1; M8, M,„ &c, are only found to bear the relationships to
Q? Qi? Qi» Q3) &c.} there indicated, when each passage is free from the
effects of natural ventilation, which may arise from the air in the
passages having different temperatures, and consequently different
densities, in the ascending- and descending parts of such passages,
giving rise to forces which are not proportional to the squares of the
quantities of air in circulation in the same passage, and which may
prevail to different extents in the connected passages of the same mine;
these formulse only being strictly applicable where such forces do not
obtain; yet where they only exist to a small extent in proportion to the
forces due to frictional resistances, contractions, &c, represented by
M, Ml7 M2, M3, &c, the formulae may give useful approximations to the
truth.
(48.) When several currents of air traverse, in common with each other,
a passage unaffected by natural ventilation, if the quantities of air in
the different currents are represented by Q1; Qs, Q3, &c, and a series
of corresponding resistances by M1} Ms, M3, &c, while the united current
is represented by Q=Qi+Qa + Q8, &c.t and the actual pressure required to
force one cubic foot of air per minute through the passage is denoted by
M, we should evidently have
M, = (.^y M;M,= (-|-)a M;M, = (-<L)2 M&c.,[78]
provided we assumed the corresponding resistances of such values that
QfM, = Q^M2 = Q^M3 = Q3M; in which case we could calculate the
expenditure of pressure, from any of the separate currents, or from the
united current, encountered in the passage in question—the resistances
M3, M2, Ms, &c, being, however, hypothetical—a process which may, in
some instances, be useful in reducing the calculations, whether in
investigating the theory of ventilation, or in determining the
resistances which any particular current of air actually
124
encounters, as distinguished from others with which it may in some parts
of its route be intermixed.
(49.) In order to exhibit in a general point of view the benefits
arising1 from " splitting" or dividing the air in mines, into different
currents, each having a portion of the workings of the mine allotted to
it for ventilation, it will be assumed that the effects of natural
ventilation do not affect the results, which will be true of mines
having all the workings situated in the same horizontal plane, or, under
the contrary circumstances, of the workings lying at an inclination to
the horizon, provided the* air preserves the same temperature throughout
the whole, and there is but one downcast and one upcast shaft, as this
will render the investigation more
simple.
As, however, in this part of the subject reference will be made to the
coefficient of friction, it may not be amiss here to present a table
shewing the actual value of this coefficient, under different
circumstances, as determined from experiments made by MM. Girard,
Daubuisson, and Peclet.
TABLE 1,
Shewing the value of the coefficient of friction K, as used in the
preceding formulae ; being the height in feet of air column, required to
overcome the factional resistance encountered by one cuhic foot of air
per minute, passing through a passag-e presenting one foot area of
section and one foot area of rubbing surface to the air.
State of the internal GENERAL TEMPERATURE OF THE AIR.
Nature of the „
.,
surface of the __________Cool._______________Hot.
material compos-material composing OBSERVERS' NAMES.
ing the Air-way.
---------------------------------------------------------
the Air-way. -. ' , ^ , .
^, ,
Girard. Dauhuisson. Peclet.
f ^tm^X) ¦* ....................
long use .... S 100,000,000
Cast Iron.... ~i
Covered with soot ~i
5-2917
after long use > ....................--------------
t as a chimney, j
100,000,000
2-7517
f Rusty.......... 100,000,000 ....................
Sheet Iron .. «j New>and free from j ..........
10-583
^ rust and soot. J ..........
100,000,000
Burnt Earth 5 New, clean and free ) ..........
26-881
or Pottery. ( from soot----- >
..... 100,000,000
, 2«54
........
Tinned Iron.... Tin upon Iron.... ..........
---------------
111 ^
100,000,000
125
(50.) The general features of the mode about to be pursued to exhibit
the effects of dividing the air by splitting it into different currents
is suggested by the perusal of Mr. Combes' remarks on the same subject.
Snppose a mine, having one downcast and one upcast shaft, and an extent
of workings free from the interference of natural ventilation in any
part of them, composed entirely of galleries having' the same area and
perimeter of section in all their extent, and that such workings
present a rubbing surface to the air, which in all parts lias precisely
the same coefficient of resistance • suppose, further, that all the
workings, excepting a short distance vexy near the bottoms of the
shafts, may be successively divided into any number of different groups,
for ventilation by distinct currents of air, and so that each group,
whatever may be then* number, shall possess exactly the same development
of galleries, and the same number of angles or turnings, and be each
similarly situated with respect to the points where the air divides
itself and again re-unites before ascending the upcast shaft; and let
the following notation be adopted— M=The pressure per unit of surface,
or head of air-column, required to overcome the frictional resistances
in the shafts, and the galleries extending- from the points of division
and re-union of the air to the shafts, and which are consequently
traversed, in the same manner as the shafts themselves, by the whole of
the air. A=The area of the upcast shaft, in feet.
Q=The cubic feet of air per minute, ventilating the whole of the mine.
P=The ventilating pressure employed, expressed in height in feet of
air-column, being in fact the same as D0—JJ0 in our preceding
investigations. L=The length in feet, of the whole extent of the
air-ways lying between the points where the air divides and again
re-unites, respectively; but not including the shafts, and portions of
air-way extending from them to the points of division and re-union.
c=The perimeter of the section of the air-ways which form the different
groups of workings, expressed in feet. a=The area of the uniform section
of the air-ways, admitting of division into groups, expressed in
superficial feet. k=The coefficient of friction, suited to the nature of
the air-ways which
are divisable into groups, as described, n—The variable number of groups
into which the workings are divided for the purpose of separate
ventilation.
Then by [10], y -jj- being taken instead of the square of the velo-Vol.
III.—Dec, 1854. s
126
city, to which it is equal,) we have qqi gnn A2" f°r the pressure
in head of air-column, due to the velocity with which the air leaves the
top of the upcast shaft; and P — 9sir00"A8 w^ ^e ^e Pressure remain ing
applicable to the resistances j the resistances in the shafts and the
undivided parts of the air-ways will require a pressure=Q2 M to over-
come them, leaving P — SsTfiCKfA2" —¦ Q2 M to overcome the resistances
which present themselves in the portion of the workings admitting of
being divided into groups, as already explained; the resistance in these
workings before splitting the air at all, according to [63J, would be
expressed by Q2 —— j tmt if they were divided into n perfectly equal and
similar groups, the effect would be equivalent to increasing the area
open to the air, n times, or to (n a); while the rubbing surface exposed
by the air-ways, L c, would remain unaltered, and, therefore, the
pressure due to
the resistances in question would become Q2 —,—« ; or if we consider
it in another point of view, and look upon the area as becoming (n a),
T
and the length of passage pursued by the air, as being reduced to —
we must also consider that the perimeter of the section of the air-way
allotted to each group is unaltered, and the sum of all the perimeters
in
the different groups is therefore n c : and if for L we substitute —, we
n
must at the same time substitute n c for c, and this gives the same
result,
1 T
or Q2 /ri"aY>> as tn-e pressure due to the resistances alluded to,
when the
air is divided into n different splits or divisions; the resistance just
alluded to being added to those before mentioned, will indicate the
total expenditure of ventilating pressure, which must be equal to the
entire pressure P, employed, or
P= 231,600 A' +<yM + » W..............TO
and hence
Q= i \r TTT................£W]
4 231,600 A» + M + n8 a8
127
when the air is divided into n splits of equal amount: before the air is
split at all, and when the whole column is required to traverse
successively all the workings, n becomes equal to unity, and
consequently
«- i FM^ i^.................tra
J 231,600 Aa + a8
Let it now be presumed that, in the example mine we have endeavoured to
describe, the ventilation is caused by a pressure equal to that arising
from a column of air 200 feet high, the area of the upcast shaft being
taken at 100 superficial feet; the value of M, or the head of air-column
due to the shaft and other unreducible resistances, when one cubic foot
of air per minute is in circulation, we will suppose to be
'000,000,014,568,4: feet; the extreme minuteness of this number arises
from the quantity of air forming- the unit of circulation, being only
one cubic foot per minute; the coefficient of resistance in the
divisable parts of the workings we will
. , 3-03030 , . , ±. .
suppose to be k = |()^ „*„ „„¦» • the entire length of such passages DO
miles or 264,000 feet; the perimeter of the section of these air-ways we
will take at 30 feet = c; and its area a = 40 feet; then before
splitting the air we should have for the quantity of air in circulation,
by [75]
0- 2°°
- 7288
^ ______I______+-000,000,014,568,4+-0Q0'000'03°'303X264'Q00X^ ~ '
^ 231,600 X 100a >">«>> -r 40a
cubic feet per minute.
If we conceive the £'- in the same mine to be divided, by splitting,
into 10 equal currents, each traversing only one-tenth of the divisable
-part of the workings, we should then have, by [74]
Q= 200
, ~~
1_______[ nnnnw^A rroj , -000,000,030,303 X264,000 X 30
„ 231,600X100* + •000'000'014'568'4 + -J"-----------ioTxTo^-—~"
=103,280 cubic feet per minute, instead of the former quantity 7,288
cubic feet per minnte, each of the 10 splits being 10,328 cubic feet; so
that upwards of 14 times the quantity of air would be introduced into
the mine by the same amount of ventilating- pressure per unit of
surface, by being divided into 10 equal splits, as compared with its not
being divided or split; each of the splits actually embracing more air
than the entire quantity, before splitting was resorted to. It must,
however, be noticed, that to maintain the same ventilating pressure for
different quantities of air, requires that the power, whether obtained
by furnace action
128
or by machinery, driven by engine power, should increase in the same
proportion as the quantity of air in circulation is increased, and the
consumption of fuel will, in either case, follow the same proportion. To
have obtained an equal increase, without resorting to splitting the air,
would have required the power and consumption of fuel to have increased
in the ratio of the cube of the quantity of air.
In the case we have taken, the resistances arising in the shafts and
undivided parts of the air-ways near them, amounts to one-third of the
entire pressure employed when the air is divided into 10 equal parts,
and this is no unusual proportion to be met with in practice, had it
been of less amount the benefits of splitting the air would have been
greater. By substituting successively 1, 2, 3, 4, &c, for n, in [74], as
the number of equal currents into which the air-ways are divided, we
obtain data for constructing the following table—
129 TABLE 2.
Table, shewing1 the result of dividing such a mine as that supposed for
example into different numbers of similar and equal parts, to be
ventilated by separate currents, under a constant ventilating1 pressure.
ABC DBF
,T , Total quan- T .
Increase Decrease
No-°f tity of air I+nViCreasein Quantity of in the in the
equal Circuiatinff tiie 8™ss air in each quantity quantity
curre»f per minute quantity split or of air
of air
or splits V cuWc due to each ^^ in each in each
ofair- feet. sp^t added. gplit
gpHt>
1 7,288 ...... 7,288 ........
2 20,328 13,040 10,164 2,876
------
3 36,038 15,710 12,013 1,849
------
4 52,129 16,091 13,032 1,019
....
5 66,667 14,538 13,333 301
------
6 78,568 11,901 13,095 ....
238
7 87,706 9,138 12,529 ....
566
8 94,652 6,946 11,831 ....
698
9 99,652 5,000 11,072 ....
759
10 103,280 3,628 10,328 ....
744
11 105,940 2,660 9,631 ____
697
12 107,927 1,987 8,994 ....
637
13 109,402 1,475 8,416 ....
578
14 110,533 1,131 7,895 ....
521
15 111,421 888 7,428 ....
467
16 112,102 681 7,006 ....
422
17 112,641 539 6,626 ....
380
18 113,062 421 6,281 ....
345
19 113,422 360 5,970 ....
311
20 113,704 282 5,685 ....
285
29 114,883 ...... 3,962 ........
30 114,939 56 3,831 ....
131
39 115,227 ...... 2,955 ........
40 115,245 18 2,881 ....
74
49 115,347 ...... 2,354 ........
50 115,355 8 2,307 ....
47
99 115,455 ...... 1,166 ........
100 115,456 1 1,155 ....
11
Infinity. 116,003 When the air does not traverse the workings.
(51.) If, however, in the same mine which has been taken in the
foregoing example, we were to presume, that, instead of the pressure
employed per unit of surface being constant, the horses' power exerted
to produce ventilation remained constant, as would be the case where
fans, Harty pumps, and other machines, are employed in the production of
ventilation; then the effects of dividing such mine into different
numbers of equal groups, for separate ventilation, would be somewhat
different as regards the resulting quantities of air, as will appear if
we let, (as in formula [46,])
130
jET=Horses' power of engine j and further substitute in [46], the value
of p + p', which will evidently be w P; where w is the weight in lbs.
per cubic foot of air of the density of that in which P is estimated,
(for finding* the value of w see [43], ) we obtain
H~ ~3poo~......................[76]
and
p_ 33,000 H _
w Q ...................*- -*
If we further presume that the head of air-column P, is estimated of the
density due to dry air of the temperature of 61°, under a pressure of 30
inches of mercury, we find, by [43], that
1-3244 x 30 A«/.^« n
W - 459 + 61 " -076407 lbs-
which being* substituted in [771, gives
P - 33,000 H ~~ -076407 Q
and if this value of P be substituted in [74], we obtain the equation
33,000 H n _ __________-076407__________
r781
s 231,600 A2 + M + n3 a8 If we now presume the engine employed to
produce the ventilation to be of 37*046 horses' power; and if we replace
the literal quantities in [78], by their presumed numerical values in
the mine which has been already adopted as an example, (excepting only
the literal quantity n, denoting the number of equal splits of air,) we
obtain a formula in which we have only to replace n by the number of
splits into which we may conceive the air to be successively divided, to
obtain the corresponding values of Q, or the quantity of air in cubic
feet per minute put into circulation j the formula being,
I 33000x37-046
__________________________-076407_____________________________
Q= „ 1 '
-000,000,030,303 X 264,000 X 30 3J 281600X100'
+-000,000,014,568,4+—^-----------^---------------
If the number of splits be increased without limit, and consequently the
last expression in the denominator were rendered of no value; in other
words, if the air only had to traverse the shafts, and the air-ways
extending from them to the points where the currents divide and
re-unite, respectively; then 37-046 horse power would put into
circulation
131
1 33000 x 37-046"
'076407 -,™w
Q =---------^------------------------------------- = 102,175
^231600 xlOO* +'000,000,014,568,4 cubic feet of air per minute.
Table 3 shews the results of dividing the same mine into different
numbers of equal parts, for separate ventilation, when the power
employed is constant.
TABLE 3.
Table, shewing-the result of dividing" such a mine into different
numbers of similar and equal parts, to be ventilated by separate
currents of air ,• the power being-constant.
,T » Total quan- n ... ~ Decrease
No-0f tityofair Increase of Quantlt? °f in the
equal .•>,,. . ¦- air in each „„„„,.•,.„
currents circulatino air due to m fa quantity
... per minute, each split £. '.r i. of air
or,s? in cubic added. cubic feet, fa ea(jh
of air. feet_ per minute. gp]it<
A B C JD
E
1 16,198 ...... 16,198 ....
2 32,094 15,896 16,047 151
3 47,011 14,917 15,670 377
4 60,129 13,118 15,032 638
5 70,844 10,715 14,169 863
6 79,042 8,198 13,174 995
7 85,058 6,016 12,151 1,023
8 89,492 4,434 11,187 964
9 92,616 3,124 10,291 896
10 94,850 2,234 9,485 806
11 96,473 1,623 8,770 715
12 97,675 1,202 8,140 630
13 98,563 888 7,582 558
14 99,241 678 7,089 493
15 99,772 531 6,651 438
16 100,177 405 6,261 390
17 100,498 321 5,912 349
18 100,755 257 5,597 315
19 100,963 208 5,314 283
20 101,132 169 5,057 257
29 101,828 ...... 3,511
30 101,861 33 3,395 116
39 102,037 ...... 2,616
40 102,042 5 2,551 65
49 102,102 ...... 2,084 ____
50 102,106 4 2,042 42
99 102,166 ...... 1,032
100 102,167 1 1,022 10
Infinity. 102 175 When the air does not traverse the
working-s.
132
An examination of these tables will shew how very great is the increase
in the air circulating', which may arise from judiciously splitting* the
air in a mine, whether the ventilating pressure be supposed to remain
constant, as in Table 3, or, on the other hand, the power employed be
supposed to be uniform; and the difference between the one and the other
of these suppositions may be estimated by comparing the tables, one with
the other, commencing the comparison at the point where the air is in
each case supposed to be divided into 6 splits, the quantities then
being nearly equal to each other.
In the example mine, if the resistances represented by M, as due to the
shafts and air-ways near them, supposed to be traversed in every
instance by the entire undivided current, had been of less amount,
owing* to the shafts being- larger and the said air-ways of less extent,
then the g-ood effects of splitting* the air would have been enhanced,
as this invariable resistance would have been of less amount, so that a
larger proportion of the total resistances would have been reduced by
splitting the air.
If, for instance, the head of air-column due to these resistances had
only been '000,000,000,818,2 feet for the circulation of one cubic feet
of air per minute, instead of -000,000,014,568,4 feet, as has been
presumed; then, for a constant pressure of the same amount as in Table
2, we should have the quantities represented by [74],
Q sb I "" 200
1______I______ 7 -000 000 000 818 2 , "000 WO-30,303 X 264,000 X 30
<s| 231600 X 1002 + 000,000,000,818,2 + tf~^W*
giving rise to the following table of results.
138 TABLE 4.
Table, shewing the result of dividing- such a mine as that just
described, into different numbers of similar and equal parts, to be
ventilated by separate currents, under a constant pressure.
T . j Increase Decrease Total quan-
£™^JZ Quantity of of the of the
No. of tity of air ^equanuty ah, in each quantity quantity
equal circulating- nvffjjLj split or of air in of air in currents
per minute, s*7 a,-e ' current, in each split, each split,
or splits in cubic ln ?U I0 cubic feet in cubic in
cubic
of air. feet. ¦' ?er per minute, feet per
feet per
mmute- minute, minute.
A B C D E
F
1 i 7,302 ...... 7,302 ........
2 I 20,623 13,321 10,311 3,009
3 37,763 17,140 12,583 2,277
4 57,807 20,044 14,452 1,864
-----
5 80,000 22,193 16,000 1,548
6 103,550 23,550 17,258 1,258
7 127,770 24,220 18,253 1,005
8 152,770 25,000 19,096 843
9 176,910 24,140 19,657 561
10 200,000 23,090 20,000 343
-----
11 221,670 21,670 20,152 152
-----
12 241,820 20,150 20,152 ........
13 259,940 18,120 19,995 ....
157
14 276,290 16,350 19,735 -----
260
15 291,110 14,820 19,407 ....
328
16 303,940 12,830 18,996 ....
411
17 315,210 11,270 18,542 -----
454
18 325,040 9,830 18,058 ....
484
19 333,639 8,599 17,560 ....
498
20 341,126 7,487 17,056 ....
504
29 377,466...... 13,016 ........
30 379,472 2,006 12,649 -----
367
39 390,256 ...... 10,007 ........
40 390,941 685 9,774 ....
233
49 394,992 ...... 8,061 ........
50 395,285 293 7,906 -----
155
99 399,383 ...... 4,034 ........
100 399,401 18 3,994 -----
40
( The quantity of air Q—which would be
] put into circulation if the air only tra-
Infinity. 400,000 < versed the shafts and air-ways extending-J from them
to the points of the division or
^_________________ L splitting-, and reunion, respectively.
It will be seen, that owing to the reduction in the amount of the
constant resistances, the maximum quantity of air in Table 4 is 400,000
cubic feet per minute, under a ventilating pressure, of 200 feet of air,
compared with a maximum quantity of only 116,003 cubic feet per minute,
arising from the same ventilating pressure, in Table 2, although the
general workings of the mine, in the two cases, present exactly the Vol.
III.—Dec, 1854. t
134
same amount of resistance; the greater quantity being- entirely due to
the lesser shaft and constant resistances; and a comparison of the two
tables will shew how much the quantities are affected by the supposed
alteration in these resistances, when the workings are presumed to be
divided into various numbers of equal parts, for separate ventilation;
from whence the necessity of making' the shafts and general air-courses
in their immediate vicinity, of great sectional area, will appear, in
order to produce a good and economical ventilation.
Adopting the same reduction in the amount of the shaft and constant
resistances, and presuming that a constant 'power had been used to
produce ventilation, of the same amount as in Table 3; viz., 37"04:6
horses' power, the quantities of air put into circulation under
different numbers of equal splits, all other conditions being the same
as in Table 3, would be given by the formula [78], or by
j ' 33000"
"x"*37-046 ""
n _ I _._____.________ -076407__________________
^"" 1 ¦"" -000,000,030,303 X 264000 X 30 8J
231600 X 100" +-000,000,000,818,2 + ---- ^ x 403 -,-------
the results of which are shewn in Table 5.
135 TABLE 5.
Table, shewing1 the result of dividing- such a mine as that described,
into different numbers of similar and equal parts, to be ventilated by
separate currents, under a constant power.
¦v~ ~c Total quan- T n__... Decrease
No. of ... J . Increase Quantity „X
„„.,„i tity oi air , .. » • J of the
equal . J ¦, ,. m the i of air
? . circulating- ..tt. . , quantity
currents „ • ,° quantity by in each ^ Z ¦
or snlits Pei minute' pach s"nlif unlir or ofair
01J^ltS in cubic eacj\sPllfc 8pllt °,r in each
of air. feet> added. current. ^
A B CD M
1 16,217 ...... 16,217
2 32,404 16,187 16,202 15
3 48,500 16,096 16,167 35
4 64,420 15,920 16,105 62
5 80,000 15,580 16,000 105
6 95,088 15,088 15,848 152
7 109,510 14,490 15,644 204
8 123,153 13,643 15,394 250
9 135,790 12,637 15,083 308
10 147,360 11,570 14,736 -346
11 157,840 10,480 14,349 387
12 167,250 9,410 13,937 412
13 | 175,500 8,250 13,500 437
14 J 182,790 7,290 13,056 444
15 189,260 6,470 12,617 439
16 194,785 *5,525 12,174 443
17 199,570 4,785 11,739 435
18 203,700 4,130 11,317 422
19 207,275 3,575 10,909 408
20 210,365 3,090 10,518 891
29 225,150 \..... 7,764
80 225,850 700 7,528 236
39 230,110 ...... 5,900 ___
40 230,377 267 5,759 141
49 231,965 ...... 4,734 ___
50 232,080 115 4,641 . 93
99 233,681 ...... 2,360 ___
100 233,688 7 2,337 23
Infinity. 238,921 When the air does not pass beyond
I the splitting- point.
With reference to Tables 2 and 4, where the ventilating pressure
employed is supposed to remain constant, the consumption of fuel would
be nearly proportional to the quantities of air exhibited in the tables
as circulating-, in the columns marked B; because if furnace ventilation
were employed, the increase of temperature required to be imparted to
the air to maintain a constant ventilating pressure would be the same;
but the unities of heat, and consequently the consumption of fuel
required to effect this,
136
would be nearly proportional to the quantity of air to be heated; the
only reason for a deviation from this, being alterations in the loss by
cooling' in the shaft; &c.; and if, on the other hand, engine power were
employed, the pressure being constant, the power itself would require to
increase with the velocity of the air, and the consumption of fuel would
increase in the same proportion.
In Tables 3 and 5 the consumption of fuel may be regarded as
being-constant, because, since the power is constant, the ventilating
pressure multiplied by the velocity of the air must be constant; any
increase in the quantity of air requiring to be heated by a furnace
would, therefore, be accompanied by a proportionate decrease in the
pressure, and consequently in the heat or temperature required to be
imparted to it. If engine power were employed, then since the power is
constant, the consumption of fuel may be regarded us being so likewise.
The resistances in the shafts and air-ways traversed by the undivided
current, are, in Tables 2 and 3, taken at amounts not widely differing
from cases met with in mines, so that these tables may be regarded as
giving a more ordinary general view of the benefits arising from
splitting the air into equal parts, than Tables 4 and 5, where these
constant resistances have been presumed to be of unusually small amount,
for the mere purpose of shewing the desirableness of reducing them to
the lowest practicable amount.
In Tables 2 and 3, the constant resistances represented by
9^1 POO Aa ""•" ^> are Pro^aDty ^r representatives of these resistances
as they frequently occur in practice; being, in fact, equal to one-half
of the resistances which arise from those workings which we have
supposed to be capable of division, for the purpose of separate
ventilation; and, consequently, equal to one-third of the total
resistances, when we suppose the air to be divided into 5 equal splits.
This conclusion is supported by the case of Hetton Colliery, as alluded
to by Mr. Wood in his Paper on the Relative Value of the Furnace and the
Steam Jet; where we find that when the shaft temperatures were very
high, which would probably cause these resistances to assume an undue
proportion to the total resistances, they formed, in one instance, 75
parts out of 115 of the resistances of the air-ways, and 96 parts out of
128 in
75 another case : that is to say, in the former case —TqTT of the total
ven-
96 tilating pressure; and ~nHK~ of that pressure, in the latter case;
where
137
a high upcast temperature would probably tend to make these proportions
unusually great; while this would be further promoted by the general
resistance of the mine itself being exceedingly small, as may be seen in
(28). The following Table shews the cases in question.
TABLE 6.
Table, shewing the pressures expended in producing- ventilation, in two
experiments at Hetton Colliery; and the same, as allowed for in Tables 2
and 3, in this memoir.
I Pressures,
expressed in feet of ;iir column, of the yeiocj+v
Average Quantities Temperature of the Down-cast
Shafts. ^ ^
Temperature of i of air per _ 0ver
Overcom- Total ah' ln
aempeiiuuie 01 i Genera- coming
_ *v^tt^
ting the there- ih, .Mta Ventilating the Up-
Shafts. minute, Velocity sistances Sum of tne ieMb"
Pressure cast
. .. ¦* a" ?ft'1te tancesin . .
' Shafts,
in cubic top of Shafts -n « v being
the
-------------------------' the Up- and Air- -^4'"^
thp ,,ivi,ip,i , in feet
. . „„,,* „.lva meanioeit sum of
Down- Up- feet. ca>t ^3"
per
', Shaft. near Ai_
_„v, to a. r} . .
cast. cast. them
Air-ways, p <} Cr. minute.
______________________________________________
A B \ C D E . F Q
H I
lstcuse i43°'5 17S° !2lM93 10'43 64'61 75-04 115-27
190-31 29-16
Jnd'oaae i43°'5 211° 225,176 12-37 84-18 9C55 128-45
225-00 32-57
I^plite \........ 6G'G67 1-92 64*75 66'67 133*33
200'00 11'11
JSJ \........ 70,844 2-17 73-12 75-28 150-57
225-85 11-81
In the first of the above experiments or cases at Hetton Colliery, the
sum of the pressures due to the final or upcast shaft velocity, and to
the resistances of the shafts and principal air-ways extending from them
to the point where the gauge was fixed, was -651 of the total
ventilating pressure, and, in the second case, it was *752 of the total
ventilating pressure ; being probably a larger proportion of the
pressure producing- ventilation in the latter than in the former case,
owing to the greater amount of expansion in the air in the upcast shaft
in the latter than in the former case, arising from the higher
temperature prevailing* in the furnace drift and in the upcast shaft; as
the resistances of a frictional character probably increase with the
square of the velocity, quite independent of any change in the density
of the air, so long as it exists under the same barometrical pressure.
(52.) In what has been stated relative to the effects of splitting the
air iu a mine, all the splits have been presumed to be of equal amount,
both as to quantity of air, and to the extent of workings ventilated by
138
them, which conditions are most favourable to the increase of
ventilation, but are seldom or never fully attainable in mines.
In order to show the effects of splitting1 the air in mines, into
currents of different amounts, ventilating* workings differing- in
extent and resistances, let us take the same mine which we have made use
of in constructing Tables 2 and 3, where the constant resistances are
taken at an amount not unlikely to be met with in practice; and let it
be presumed that into whatever number of divisions the 50 miles of
g-alleries are conceived to be divided for separate ventilation, each of
the currents, splits or branches from, and also reunites to, the general
or main current at the same points. This supposition, in the mine we
have supposed, involves the necessity of the pressure required in each
of the separate currents, being equal to each other, as the air will
naturally divide itself in such a manner as to suit this condition. In
general, it may be presumed, that the quantity of air in each split]
should be proportional to the length of the galleries allotted to it for
ventilation, and we will therefore adopt this proportion in the present
illustration, involving the necessity of the resistances offered by the
whole of the routes, excepting the longest one, being so artificially
increased, by regulators or contractors placed in them, as to make the
expenditure of pressure in each of the shorter routes as great as that
in the longest one, even although the air in them is less in amount, as
their length is shorter than the longest route; and, under these
circnmstances, it is evident that the ventilation will be less
effectual, on the whole, than if the splits had been equal and no
artificialresistances had been created, seeing that into whatever number
of splits the air is divided, all will be throttled excepting the
largest one.
Adhering to the notation already adopted in discussing- the effects of
splitting- the air in a mine, and in addition letting
lj, 12, 13, &c.f represent the lengths of the separate divisions for
distinct ventilation, the longest one being represented by L, and
letting
li; % <l3> <&c-; represent the quantities of air circulating in these
divisions, respectively; that in the longest and uncontracted division
being denoted by Q, then we have
L=L + lx + 18 + 13, &c.............................[79]
and also
Q=# + q, + q9 + qw &c.............................|80]
139
and we have already taken in the supposed mine M=-000,000,014,568,4
A=100
k= -000,000,030,303 L=264,000 c=30 a = 40 and P =200
giving-, as the quantity of air before splitting-, or when n=l,
200 ""'
1 -000,000,030,303 X
264,000 x 30
S4 231,600X100* + -000,000,014,568,4 + ' lx4Q3
=7,302 cubic feet per minute, as before found. Before splitting- the air
the pressure due to the frictional resistances of the mine, lying beyond
the points where the air is divided and again reunited, respectively, is
expressed by
P-QJ(23i^+M) ...............W
where M is the specific resistance of the downcast and upcast shafts,
furnace, furnace drift, and united air-ways, where the air is not split.
If we now conceive the passages of the mine lying beyond the points of
division and reunion of the currents of air, to be divided into distinct
parts for separate ventilating- currents, as before stated, and that
artificial obstructions or regulators are introduced into each of the
routes, excepting-the longest one, so as to reduce the quantities of air
circulating in such routes, until the quantity in each becomes
proportional to the length of its own route which it is destined to
ventilate ; and if by if we denote the specific resistance of the
longest route, by L its length, and by Q the quantity of air
circulating- in it, in accordance with the notation indicated,
P-(23W0A»+M)Q!=,?if................Wl
but since we have presumed the quantities Q, q1} q2, q8, &c, to be
proportional to L, lx, 12, ls, &c, respectively, the lengths they have
to ventilate, we get
Q : L :: Q : L :: qx : \ :: q8 : i8 •: q3 : i3, &o.......[83J
and hence
<?=Q4...........................1*3
140
and by substituting this value of Q in [82], we get
P_f___I___ +MW=Q*--lf..........[85]
V231,600 A3 )H H V
and hence
P = rp5-----L_ + M + ~iYl ...........[86]
1231,600 A2 L3 >
and
^T^00A3 + M + UM
After finding- the value of Q by [87], it will be easy to find the
values of the separate currents Q, qt, q2, q3, &c, because by [84],
Q = -<£- Q; qi = -jj- Q; q2 = -jj- Q; q3 = ~^~ Q &c.....[88]
In the case in hand, the specific resistance .ftf will be----— , and
hence
§-*-^-.................P9]
as the air-ways are supposed to have an uniform area and perimeter of
section throughout; so that in this instance,
Q= -------JL. ~................[90]
N 231,600 A* ^ + L2 a8 Applying this formula to the mine which has been
supposed for example, as in Tables 2 and 3, where the shaft resistances
are greatest; if, in the first place, we assume the pressure to remain
constant, as in Table 2, at 200 feet in height of air column; and
suppose the air to be divided into two currents, one of the routes being
half the length of the other, and one of the currents, in like manner,
being equal to one-half of the other, to circulate in the routes to
which they are respectively proportional, we get
___________________________________
]
200 . °"
Q — f~
-000,000,030,303 X (26400 x ?)3 X SO „ 231,600X100* +
-000,000,014,568,4 +---------------264,000* X 40= _
= 13,096 cubic feet of air per minute; whilst by Table 2, we see that if
the routes had been of equal length, and aired by equal currents, so as
to have required no regulators, the quantity of air in the two currents
would have been 20,328 cubic feet; so that we only obtain an increase of
5,808
141
on the original quantity before splitting, instead of an increase of
13,040,
as is stated in Table 2, to result from the splits being equal to each
other.
The quantity of air in the longest route would in this case be
2 -j Y'tj- X 13,096 = 8,731 cubic feet; the quantity in the shorter
route
being -^ + q x 1-3,096 = 4,365 cubic feet per minute. See [88].
It may be seen that instead of using the absolute lengths of the routes,
in these calculations, quantities proportional to them are used, but as
they only occur in their ratios, this will not affect the correctness of
the results.
If we next conceive the mine to be divided into 3 parts, the lengths of
which, and the currents of air traversing -them are respectively
proportional to the numbers 1, 2, and 3 j then
— 200
Q~] (¦000,000,000,431,6+-000,000,014,568,4)+-000'000-^0°^ ^X VX00
= 20,333 cubic feet of air per minute, whilst by Table 2 it appears that
if the three routes had been of equal length, and aired by equal
currents, so as to have required no regulators, the quantity would have
been 36,038 cubic feet, instead of only 20,333 cubic feet; even under
the same ventilating pressure.
The quantities of air in each of the routes would be,
3 x 20 333 In the longest route......i '4. "o ''+'4 ~ 10,166 cubic feet.
In the next shorter route.. %-37-p-Trq- = 6,778 " "
1 v 20 333 In the shortest route .... ^ * ~ '—^ = 3,389 " "
being quantities respectively proportional to the lengths of their
routes. In a similar manner to the above, by the use of formula [90] to
determine the gross quantity Q, and that of [88] to determine the values
°f Q) qi? q2> q3? &c->tne following table has been constructed to show
the quantities of air due to the constant pressure, as the same mine is
supposed to be successively divided into 1, 2, 3, 4, 5, 6, 7, 8, 9, and
10 distinct parts for separate ventilation, always, however, forming in
their lengths an arithmetical series, having for a common difference the
length of the shortest route, and aired or ventilated by quantities of
air directly proportional to their respective lengths; in the column C,
of the table, are exhibited the quantities of air which would have been
put into circulation in each split in the same mine, presuming the same
constant pressure had been employed, and that the mine, instead of being
divided and Vol. III., Dec, 1854,
' v
143
ventilated in the manner stated, had been divided into equal numbers of
splits, of equal lengths, and ventilated by currents of equal amount, as
in Table 2; a comparison of the quantities in columns B and Cwill show
the great advantages of having the resistances due to a given quantity
of air, and the currents themselves, as nearly of equal amount as
possible when the general requirements of all parts of the mine are
nearly equal.
TABLE 7.
i ~~ ~~
Ouantities Quantities
Number v, .. when the Differences, T
when the ,., , . . ,, ' Loss per
. r.„,. splits are lost by the J \
j_«i„ splits are ,f . J,., cent, of
of splits r ... the same inequality
l«5"5n™m^ of the b S**te-
of air. »™ but all currents. I™"11* equal.
A B C JD B
1 7,288 7,288
2 13,326 20,328 7,002 34*j
3 20,333 36,038 15,705 43*
4 28,006 52,129 24,123 46£
5 36,051 66,667 30,616 46
6 44,180 78,568 34,388 43|
7 52,131 87,706 35,575 40J
8 59,680 94,652 34,972 37
9 66,667 99,652 32,985 33 10 72,991
103,280 30,289 29|
An examination of Table 7 clearly shows the great increase which can be
made in the quantity of air ventilating- a mine, having the resistances
of the routes and the quantities of air ventilating* them improperly
proportioned ; by so altering them, that the squares of the quantities
of air in each route, taken from its entering, up to the time of its
leaving the mine, multiplied into the specific resistances, shall be of
equal amount in each, (presuming* the mine to be free from natural
ventilation, or, otherwise allowing for its effects,) while the
quantities are proportioned to the requirements of the routes they
ventilate, after the removal of all artificial contractors or
regulators.
The table presumes the pressure to remain constant before and after
143
the alteration; by furnace action it is probable that this would be
nearly realized, in many cases, without altering the furnace, as the
fuel consumed may be presumed to be nearly proportional to the quantity
of air passing over the same furnace.
(53.) If, however, a constant power, requiring a constant consumption of
fuel, were employed before and after such a change in splitting the air,
the benefits resulting would not be of so great an amount. And if before
the change of air, the shorter routes had an undue share of the air, the
increase in the total quantity in the mine, by such a change, would not
be so great as in the table, although the actual benefits might be so,
from an improved mode of distributing* the air. If, on the contrary, the
shorter routes had less than their requirements, in proportion to the
whole, the change would be of still more benefit than is exhibited by
the mere quantities; as, while they would be increased by such a change,
in a higher ratio than is shown by the tables, the increased quantity
would be more properly distributed.
By substituting in formula [90], the value of P in [77], and reducing,
we obtain
. 83000 Ji'"^
•076407
Q= ZHZ—M tJ. ..............W
*4 231,600 A2 + M + La a8 the value of w being taken at "076407 as
before.
If we apply this formula to the mine already taken for example, and
presume the ventilating power employed to be the same as in Table 3, or
37*046 horse-power j and, in the first place, suppose the mine to be
divided into two different parts, in the ratio of 1 to 2, for separate
ventilation, we obtain,
p 33,000 x 37-046
0_ I
-076407_________________________
^ ~~ 1 „_ „ n
-000,000,030,303 X(264U00XgjaX 30 S4 isT^OOxTOO* +
-000,000,014,568,4 + ^^J—_4------
= 24,220 cubic feet of air per minute which would pass through the
2 mine, -,- ¦, „ of it in the route of which the length is 264000 x
2 1
9 = 176,000 feet; and -•-,- , ¦ >5 of it in the other route of which
the
length is 264,000 x -., , »¦ = 88,000 lineal feet; that is,
presuming
the necessary regulator to be introduced into the shorter route. The
following table has been constructed from the formula [91].
144 TABLE 8.
Number Quantities of air Quantities of air
Differences, Loss per
in the entire mine, in the entire mine, Iost by the inequality
cent, of
of when the splits form when the splits are ' Qi
the * ' greater
the arithmetical "O^"*111 routes and splits.
quantities.
Currents. ratio stated. Table 5.
r u
Cubic feet %* minute. Cubic feet ty minute. Cubic feet ^ minute.
1 16,198 16,198
2 24,220 32,094 7,874 24|
3 32,100 47,011 14,911 31|
4 39,737 60,129 20,392 34
5 47,022 70,844 23,822 33 \
6 53,850 79,042 25,192 32
7 60,130 85,058 24,928
29J
8 65,804 89,492 23,688
26)
9 70,844 92,616 21,772
23J 10 75,257
94,850 19,593 20|
A comparison of Tables 7 and 8 shows that in the case of the power
employed being constant, the loss arising from the inequality of the
extent of workings and of the quantities of air ventilating them in the
different splits, although of serious amount, is yet rather less than
the loss arising from the same cause when the pressure per unit of
surface is
constant.
When the power is constant, the ventilating pressure will he inversely
proportional to the quantity of air in circulation in a given time, and
when the pressure is constant, the power will he directly proportional
to the quantity of air circulating in a given time.
It is true, that by contracting the shorter routes to a less extent than
has been presumed in constructing the tables, a larger quantity of air
than is shown in the tables, would be found to circulate in the
particular routes where such reduced contraction existed, but this would
have the effect of increasing the amount of pressure absorbed by the
general resistances in the shafts and undivided air-ways near them, and
would, con-
145
sequently, leave less pressure to overcome the resistances in the
air-ways over which the splits are effected, and would thus reduce the
quantity of air in the whole of the other splits. Since, in general, we
may regard the quantity of gas given off, and the number of workmen
employed in various parts of a mine, to be rather proportional to the
extent of galleries in each part or split, then in any other proportion,
the principle which has been adopted for constructing the tables cannot
but be regarded as a legitimate one for a general illustration;
notwithstanding which, it will doubtless often be proper to depart from
the broad principle just exhibited, as these conditions will seldom
obtain to the full.
(54.) We may obtain a more full view of the effects of dividing the air
into equal and unequal splits, the latter in the proportions already
alluded to, by the following method.
We have [73] for the pressure due to ventilation, when the splits are of
equal amount,
p = Q*f-----1-----+ M + IiI^l...........[92]
1231600 A2 n3a3 > L
and by [77], we have
P = 33000 H
•076407Q
when w= '076407, as the weight of a cubic foot of the air in which the
height of the ventilating column P is estimated; and by substituting
this
value of P in [92], we obtain the equation
33000// n2 C 1 _, kLc) roQ,
------------= Q <--------—— + M H-------i ........[93]
•076407 Q 1231600 A3 n8a3 3 L
and hence
H== -076407 C 1 M kLol ......m
33000 1231600 A* n3a3 >
by which we can calculate the number of horses' power which would be
required to put any quantity of air, per minute, into circulation, in
the example-mine alluded to in constructing Tables 2 and 3, so long as
the whole of the splits are equal to each other both as to quantity of
air and extent of gallieries. From [91] we obtain
33000 1231600 A3 L3a3 > L J
whereby we can determine the horses' power required to circulate, in the
same example mine, the quantity of 66,6Q7 cubic feet per minute when the
mine is divided into splits, the routes of which are in an arithmetical
146
progression as to length, having the common difference equal to the
shortest route, and all, excepting the longest, being so contracted as
to render the air in each, proportional to the extent of the galleries
ventilated by it.
From these formulas, as a basis, the following table has been
constructed :—
TABLE 9.
Table, shewing- the ventilating pressures, expressed in feet of air
cohmrn, weighing •076407 lbs. per cubic foot; and the number of horses'
power required to put the constant quantity of QQ,Q67 cubic feet of air
per minute into circulation, in the example mine, to which tables 2, 3,
6, 7, and 8, bear reference; both on the supposition of the divisions
for separate ventilation being equal to each other, and ventilated by
equal quantities of air ; and also on the supposition of the length of
g-alleries in the divisions forming an arithmetical series, with a
common difference equal to that of the least division ; ventilated by
air in proportion to their respective lengths ; effected by regulators:
with the number of cubic feet of air circulated by each IB. of coal
consumed by an engine, and by each horse-power per minute.
When the currents are equal to each other. When the currents are
unequal, as above.
Number ------------¦---------------------------------------------
—¦--------------------------------------------------
. Fuel (a) Cubic feet of air
puei /g) Cubic feet of air
0t Pressure Horses 12 ft^ circulated.
Pressure Horses' 13 ^ circulated.
splits required per —'-------------------
required Per ----------------------
in head power horse- ty horse- in head
power horse- qp> horse-
of air power, power, Per lb of air
power, power, Per a.
currents column, required. per per of coul.
column, required. per per of coal,
hour, minute. hour,
minute.
A B C B B F b
c A « ¦ i f
1 16,733 2582-9 516-6 26 129 16,733 2582-9 516-6
26 129
2 2,151 332-0 66-4 201 1,004 5,005 772-5 154-5
86 431
3 684 105-6 21-0 631 3,156 2,151 332-0 66-4
201 1,004
4 327 50-5 10-0 1,320 6,002 1,133 UA-Q 35-0
381 1,906
5 200 ' 30-9 6-2 2,160 10,794 684 105-6
21-0 631 3,156
6 144 22-2 4-4 3,000 14,997 455 70-3
14-1 948 4,742
7 116 17-8 3-6 3,738 18,688 327 50-5
10-0 1,320 6,602
8 99 15-3 3-1 4,353 21,765 250 38-5
7-7 1,731 8,653
9 S9 13-8 2-8 4,825 24,125 200 30-9
6-2 2,160 10,794
10 83 12-8 2-6 5,183 25,914 167 25-8
5-2 2,589 12,943
11 79 12-2 2-4 5,453 27,266 144 22-2
4-4 3,000 14,997
12 76 11-8 2-4 5,660 28,298 127 19-7
3-9 3,391 16,956
An examination of Table 9 will show the great reduction in the pressure
and power required for sending one and the same quantity of air through
a mine, which is effected by splitting the air, and likewise the great
economy which it effects in the consumption of fuel. These benefits,
arising from splitting the air, it will be seen, are very much greater
for equal numbers of splits, when they are equal to each other, than
when they are unequal, and form an arithmetical progression of the
character described. In fact; we see that for the same quantity of air
sent through the same mine, the economy of pressure per unit of surface,
power, and fuel, is just the same for two equal, as it is for three
unequal
147
splits; for three equal, as for five unequal splits; and for four equal,
as for seven unequal splits; and so on—it being the same for six equal,
as for eleven splits in arithmetical progression, under the
circumstances described in constructing the table; the same economy
being, in general terms, only effected by unequal splits, when their
number is only less than double the number of equal splits by unity,
which are requisite to effect the same economy.
In general we may continually increase the quantity of air circulating
in a mine by dividing it into an increasing number of splits, while the
power employed remains constant; yet there is a point beyond which, if
this division or splitting of air were carried, the slow rate at which
the air in each individual split would travel might give rise to great
inconvenience, and possibly to danger itself, as it would allow gases to
lodge in spaces left in the roof by falls of stone, and in excavations a
little in advance of the openings effected for the passage of the air;
and any sudden generation of gas might not be diluted so quickly as if
the current travelled faster; besides, when a shot was fired by a
workman, giving off smoke, it might be an inconveniently long time in
getting carried beyond his fellow-workmen to leeward of him.
148
CHAPTER VI.
General Considerations relating to the Application of the Theory of
Ventilation towards guiding the Practice of it in Mines—the Indications
of Pressure Gauges.
(55.) It would, perhaps, sometimes conduce to the better ventilation of
mines, could we calculate, before making any change of air, the exact
quantities which would circulate in each of the principal and minor
splits or divisions under any given or assumed ventilating pressure, as
it would enable us to compare the results of any number of proposed
modes of dividing the air, which might be presented by the extent and
position of the workings, and thus enable us to select and carry out
that particular mode which would, under all the circumstances of the
case, give the most desirable results. The general laws recited in the
first chapter of this memoir appear to contain the elements required for
carrying this into effect, if it were possible to measure the dimensions
of all the airways, and if we could determine the value of the
coefficient of friction k, as due to each part of the same, by mere
observation as to the nature and state of the internal surfaces
presented to the moving air over their entire extent; to those at all
acquainted with the ordinary condition of the air-ways in mines, and of
their great extent and continually-varying contour of section, together
with the frequent occurrence of inaccessible fallen air-ways, only used
as auxiliary to others in an accessible state, and the leakage of air
through goaves, doors, and stoppings, not only will this proceeding
appear to be a laborious operation, but in many cases absolutely
impossible.
If, however, we had a ready and easily-applied means of ascertaining the
amount of resistance due to each air-way, and each part of an airway,
intended to be detached from or added to any other division after a
proposed change of air, there would appear to be some chance of the
149
laws of ventilation being" studied and made use of in the practical
ventilation of mines; at least this is the hope indulged by the writer,
in the belief that, in certain cases, the result would be an improved
ventilation, with its accompanying effects on the health and comfort of
the miners, and the longer duration of the perishable materials used in
mines.
The use of extremely-sensitive barometrical instruments, or pressure
gauges, suggests itself as being the most likely mode of determining-
the amount of resistance to the circulation of air, offered by an
air-way, or part of an air-way, without incurring the great amount of
trouble, or encountering directly, the difficulties which present
themselves in attempting to do this in the more obvious manner above
mentioned.
When an air-way, or part of an air-way under consideration, so returns
upon itself that the two extreme ends of it are only separated by the
intervention of a door or stopping, or at most by a distance of
unven-tilated or dumb air-way on each side of such a door or stopping-,
the use of the ordinary water-gauge, which has often been employed in
recent experiments, would appear, at least, to involve all the
principles required for determining the amount of the resistances
encountered by the air after passing one side of the stopping or dumb
air-way, and up to the time of its reaching the other or return side of
the stopping or dumb airway in which the gauge is fixed -, when,
however, the air-way or portion of air-way of which we wish to determine
the resistance, does not return upon itself in the manner alluded to;
and for the purpose now in view this will perhaps often be the case;
the water-g*auge will no longer be applicable, as it cannot, under such
circumstances, be applied to determine the difference of pressure under
which the air exists at the two ends of the air-way, or portion of
air-way under observation; and other means will require to be resorted
to. Indeed, when we consider that the total amount of resistances
encountered by the air, from its entering, up to the point where it
leaves the mine, seldom exceeds two to three inches of water-gaug-e,
representing a pressure of 10 to 15 lbs. per superficial foot, and that
the parts of air-ways which may be put under separate notice for
effecting changes of ventilation, may often not present resistances
amounting to more than ten, twenty, or thirty per cent, of the total
resistance offered by the mine, the displacement shown by a water-gauge,
on a scale so short, would scarcely be observable; particularly when it
is considered that many of the kinds of resistances indicated, decrease
in amount, not simply as the quantity, but in the higher ratio of the
square of the quantity of air traversing the passage, and the shorter
the passage Vol. III.—Dec., 1854.
x
150
the more likely is the quantity of air to he small, so that some
instrument presenting- a longer scale than a water-gauge, would appear
to he desirable for properly effecting the object here under notice.
And it would appear to he desirable that, if possible, the same
instrument shoidd offer the means of determining the difference of the
pressure under which air exists at distant points in an air-way, beyond
being applicable to the same purpose, (where an air-way may return upon
itself,) in the same manner as the ordinary water-gauge.
(56.) Before proceeding to offer any remarks as to the construction of
such an instrument as that just alluded to, let us attend to the
following remarks relative to what would be indicated by it—or by an
ordinary water-gauge, when made to connect two parts of a connected
air-way; as it is believed that some doubts, if not misconceptions, have
existed in
reference to this.
When any force is added to that by which air or gas is previously
compressed, as, for instance, to its barometrical compression; the
result of such addition of force to the, previously, stagnant air, will
be, that such air will be put into motion, or its degree of compression
will be increased, or both of these effects will be produced in a
partial degree, according to the circumstances in which the air, or gas,
is placed, and the manner in which the force is applied.
If the air or gas were confined in a close vessel, no motion of the air,
in the ordinary sense, would be produced, but its compression would be
increased to the extent of the force applied.
If, however, the air to which such force was applied, were at liberty to
move in a passage or air-way, only open at the ends; on applying the
force a general motion of the air would be produced towards the opposite
end of the air-way to that at which the force was applied, and, at the
same time, some additional compression of the air would result, having
its maximum amount at that end of the air-way to which the force was
applied, and gradually diminishing in amount towards the contrary end ;
one portion of the force applied would produce motion alone, while the
remainder of the force would only produce additional compression of the
air, and no motion; so that the entire amount of applied force admits of
being resolved into two parts; one as being equal to a force which would
have produced the same amount of motion had the air been free to move
unresisted, (except by its own inertia,) under its influence, instead
of being confined to an air-way offering frictional and perhaps other
resistances to its motion; while the other, or remaining part of the
pressure,
151
or force, would, where its maximum amount prevails, be exactly equal to
the whole of the resistances presented to it by the entire extent of the
air-way; and the sum of these two forces, would, of course, be exactly
equal to the total force applied; the additional compression produced in
the air, in any other part of the air-way, would be exactly equal to the
resistances offered by the remaining part of the air-way, traversed by
the air after passing such point; because motion, and not compression,
would be the result of the applied force, except in so far as
resistances existed, to offer the necessary re-action to compression; so
that the air, at the end of the air-way where the force is applied,
would be compressed by the pressure due to the whole of the resistances
existing in the entire length of the air-way, and also by the pressure
required to create the final velocity with which the air leaves the exit
end of sxich air-way, or, in fact, by the entire force applied, but
reduced by the portion due to the velocity of the air at the point where
it is applied; and this additional compression of the air would be found
to decrease in amount as we followed its course through the air-way, by
the exact measure of the pressure due to the resistances overcome in the
parts of the air-way so traversed, so long as the sectional area, and
consequent velocity of the air, remained the same; the amount of this
additional compression would, at each respective part of the air-way, be
reduced by the pressure absorbed in creating additional velocity of the
air, in such parts as might have less area of section than that part at
the outset; and the additional compression would be increased by any
amount of pressure arising from an increased area of section and
consequent reduction of velocity, and therefore of the pressure absorbed
by it; and at the final or exit end of the air-way, the compression of
the flowing air will not be at all increased over that of the medium
into which it is discharged; the motion of the escaping air absorbing
the whole of the remaining force at this part of the air-way, seeing
that, except in so far as resistances exist or are encountered, to
prevent motion, the whole of the applied force must result in the
production of motion only.
(57.) The excess of the force applied, over that which is expended on
the resistances of the air-way, would have been sufficient to generate a
continually increasing velocity in the air, had such increased velocity
not been attended with an increased resistance, and had it really been
applied to one and the same body of air, as in the case of a force
applied to a solid body; but, in fact, such excess is employed in
generating motion in new and distinct quantities of air every moment,
and not in
152
overcoming' frictional or other resistances of the like nature, in the
case of mines.
(58.) It is necessary to notice, particularly, that we have here been
speaking-, not of the absolute compression of the air in an air-way, but
of the additional compression resulting' from the application of a force
producing- motion in air previously acted upon only by forces which are
equal in all directions, and so producing' no motion in any direction;
because, if we commence at the end of an air-way at which such force is
applied, and traverse it in the direction pursued by the current of air,
the absolute compression of the air as we proceed may increase or
decrease to any extent, if the axis of the air-way is not all situated
in the same horizontal plane, all descents tending* to increase the
barometrical compression of the air, and all ascents having- the
opposite tendency; notwithstanding- which, the effect of the additional
force being- applied, will have resulted in increasing the barometrical
compression of the air in each respective part of the air-way, beyond
its amount in the same part of the air-way before such force was
applied, to the exact amount of the resistances encountered (owing* to
the motion resulting' from its application), in all the subsequent parts
of the air-way, including- that due to the g-eneration of the final
velocity with which the air is ejected from the exit end of the air-way,
but reduced by that portion which, at the point of observation, is
absorbed by the motion or velocity of the air at the point itself; and
the gradual loss of this excess of pressure in traversing an air-way,
will at each point be the measure of the resistances, as due to the
quantity of air passing, encountered in the preceding* parts of the
air-way. The loss of absolute barometrical pressure, where it occurs
in traversing an air-way in the direction pursued by the air, will
evidently embrace, as well as the resistances already alluded to, that
which is due to the ascents in the air-way, or, in other words, the
force necessary to overcome the gravitation of the air, in all the
ascending parts of the airway which have been traversed, reduced however
in amount by the descents, or by the gravitation of the air in all the
descending parts of the air-way, whether such ascents or descents are
vertical or inclined— the gravitation of the air being calculated as due
to the amount of vertical ascent or descent, at its actual density in
each part. But when, on the other hand, we find that in going from
one point in the air-way to another point nearer to its exit end, the
absolute barometrical compression, instead of being less, is actually
greater than the pressure at the former point, we must conclude that the
gravitation of the air, in the
153
intervening descending parts of the air-way, exceeds the gravitation of
the air in the intervening ascending parts of the air-way, and that, by
an amount representing a greater pressure than that which has been,
expended upon the intervening resistances, due to friction, angles, &c.}
and even including any expenditure of pressure due to the generation of
a higher velocity at the second than at the first point, where an
increase of velocity arises simply from the area of the section of the
moving air being less at the second than at the first point,
(59.) As the pressures arising from ascending and descending parts of
air-ways, do not, like the pressure due to frictional resistances, vary
as the square of the quantity of air circulating in a given time through
the same air-way, any such pressures will require a distinct and
separate consideration in all our investigations, where they may exist;
the amount of any such pressures, whether on the whole assisting or
retarding the circulation of air, will easily be determined by
calculating the pressure due to gravitation in all the ascending parts
of an air-way, and the contrary pressure, due to the same source, in all
the descending parts of an air-way, by observations on the temperatm*e
and barometrical compression of the air in each part, together with a
knowledge of the levels of the air-way.
(60.) The principles last alluded to, lead to the conclusion that if we
had sufficiently sensitive instruments wherewith to observe with
readiness and accuracy the amount of minute differences of barometrical
pressure, as prevailing in different parts of an air-way, in which an
observed quantity of air is circulating at the time of ascertaining such
differences of pressure, we could, (by separating from the observed
differences of pressure, the pressures arising from the gravitation of
the air in the ascending and descending parts of the air-way intervening
between the points of observation, and allowing, if necessary, for
different amounts of pressure absorbed, or rendered latent, so to speak,
by the velocities of the current at the two points of observation,)
ascertain the pTecise amount of pressure expended upon the resistances
due to friction and angles or turnings in the intervening air-way j
which resistances, as also those due to the generation of velocity,
being proportional to the square of the quantity of air circulating in a
given time, in the same air-way, would only require to be divided by the
square of the quantity of air circulating in the unit time, at the time
of the observations, to g-ive the specific resistance of the intervening
air-way, as due to the unit of air circulating in the unit of time, and
this may embrace the pressures due to velocity, or
154
not, as may be desired, and such specific resistance being- multiplied
by the square of any other quantity of air, would give the pressure
required to overcome the same kinds of resistances ia the same passage,
as due to the circulation of that quantity of air through it, per
minute, or other unit of time made use of.
(61.) In order more clearly to show what will, in the remainder of this
memoir, be intended by the term specific resistance of an air-way or
mine, let it be presumed that in the case of Hetton Colliery, as alluded
to in Table 6, there existed no sources of natural ventilation, or that
the air-ways were either all situated in the same horizontal plane, or
any ascents or descents were traversed by air of the same density, then
in the 1st case there cited, we have, from columns C and G, a specific
resistance of -000,000,002,584,4 and in the 2nd case this specific
resistance appears to be -000,000,002,533,3, found by the proportions.
Cubic Feet. Lineal Feet. Cub. Ft.
As 211,193* : 115-27 :: la : -000,000,002,584,4 and
As 225,1762 : 128 45 :: Is : -000,000,002,533,3
as due to the workings only, exclusive of the shafts, &c, the difference
in the two cases being about 2 per cent., an amount so small that it
might arise either from errors of observation, or from the existence of
natural sources of ventilation, not varying- with the square of the
quantity of air in circulation.
By a similar proportion we will find that the resistances in the
workings only, of the example mine alluded to in Tables 2 and 3,
exclusive of those of the shafts and undivided air-ways near them, are
such as to give, when divided into 5 equal splits, a specific
resistance, amounting- to •000,000,029,999, or about 12 times as great
as in the case of Hetton Colliery, already cited.
(62.) By employing- sufficiently sensitive instruments we could
evidently determine the specific resistance of any given air-way, part
of an air-way, or series of connected air-ways, or even of the entire
workings of a mine, quite independent of the quantity of air circulating
at the time, which might be greater or less, depending upon the energy
of the furnace or ventilating power employed at the time of observation,
and so be able to detect and measure the amount of any improvement or
obstruction which from time to time might occur in the same.
If, for instance, after having observed simultaneously the difference of
barometrical compression, under which the air existed at the two extreme
ends of any air-way, or part of an air-way, to which our observations
*
155
might be confined, and also the quantity of air circulating at the time
of observation, together with the amount of pressure arising out of the
gravitation of the air in the different ascending- and descending parts
of the air-way, where any such exist; we found that the specific
resistance derived from calculations based upon these observations,
amounted to a greater or less quantity than we had found by a similar
series of observations, at some earlier period, we would be certain that
in the former case, the air-ways were either in a worse condition or
more extensive than before, and in the latter, that obstructions had
been removed, or the run of the air shortened so as to lessen the
specific resistances.
This, however, is but one of the uses to which the means of readily and
correctly determining the differences of barometrical compression of
small amount, existing in different parts of an air-way, might be
applicable, because, as has already been observed, if by means of a
series of such observations, taken in suitable parts of the air-ways of
a mine, we determined the specific resistances of each of the
intervening parts of the air-ways, we would be enabled to calculate the
quantities of air which would circulate in each split, after any
proposed change of air, and, in fact, be able to choose that particular
arrangement out of any number of possible or convenient ones, which
might be calculated to give the most satisfactory results as to
ventilation.
(63.) Applying the principle, that force can only produce compression in
so far as resistance to motion exists, and that motion can only ensue in
so far as the applied force is not employed in overcoming resistances,
to the elucidation of the meaning of the displacement of the
pressure-gauge, connecting two points of an air-way, or of the
differences of barometrical compression between such two points j and
for the present confining our attention to that portion of the air-way
extending from what we shall term the 1st point of observation, being
that end of the air-way first reached by the current; to the 2nd point
of observation or the end of the air-way, or portion of air-way, reached
by the current only after traversing the whole of the air-way, or
portion of air-way, under consideration; we will perceive that any
excess of barometrical compression of the air, at the first, over that
which prevails at the second point of observation, will be composed of
the following positive pressures—
1st. That which is required to overcome the resistances arising from
friction, angles, &c, in the air-way extending to the second point of
observation from the first point.
2nd. This excess at the first point will be enhanced by the pressure
150
required to overcome the gravitation of the air in all the ascending
parts of the air-way extending between the two points of observation.
3rd. The excess of pressure at the first over that at the second point
of observation, will further be increased by the entire pressure
required to generate the velocity of the air at the second point of
observation. But the excess at the first over that at the second point
of observation will be reduced in amount by the following causes, to the
extent of each :—
1st. The gravitation of the air in all the descending parts of the
airway extending from the first to the second point of observation, as
these will tend to increase the compression at the second point of
observation, or to overcome resistances, or generate velocity in the
air, being, in fact, a source of pressure in favour of ventilation. 2nd.
By the force resulting, not in producing pressure, but motion at the
first point of observation, being the entire pressure due to the
velocity at that point. It will be perceived that when the forces just
named as tending to reduce the excess of pressure at the first over that
at the second point of observation, happen to exceed in amount the
pressures or forces tending to increase such excess, the result will be
that the barometrical compression at the first point of observation will
be less than that at the second point of observation; and if the two
points are so situated as to admit of being connected by a water or
other pressure-gauge of a similar character, the fluid will be depressed
on the side exposed to the second, and elevated towards the side exposed
to the first point of observation.
In general, however, when speaking of the indications of the gauge being
increased, it must be understood to imply an increase in the depression
of the fluid exposed to the air at the first point of observation, and
in the elevation of that exposed to the second point of observation; and
in calculations, when the pressure at the first point of observation
happens to be less than at the second point of observation, if we merely
change the sign of the displacement from positive to negative, the
formula will apply as before.
(64.) That a change of velocity in the air at the second, from that
existing at the first point of observation, does, as has been stated,
give rise to changes in the barometrical compression of the air,
requiring consideration when estimating the indications of the gauge,
resistances,
157
<fcc, may perhaps appear from considering that when the velocity of the
air at the second point of observation exceeds that prevailing at the
first point, then, since the pressure required to generate the increase
of velocity must have acted in compressing the air at the first point of
observation, or the entrance side of the gauge, while, from the
increased velocity at the second point having ensued, such force, at
that point, no longer produces compression—for the same force cannot
result in both motion and compression at the same time—so that the force
producing the increase of velocity will not produce any pressure at the
second point of observation, and consequently the barometrical
differences or displacement of the gauge fluid, as the case may be, if
positive, will be increased by the force due to such increase of
velocity, or decreased to the same extent, if negative.
On the other hand, when the velocity at the second point of observation
is less than the velocity at the first point of observation, it follows
that the positive indications of a gauge connecting the two points, or,
what is the same, the excess of barometrical compression at the first,
over that at the second point of observation, will be less than the real
amount due to the other causes affecting it, by the excess of the
pressure due to the velocity at the first point of observation over that
at the second point; because the amount of force due to such excess will
have been given out as the velocity became reduced, in the form of
momentum of the air, carrying it over resistances encountered in the
air-way lying between the points of observation, although it would not
have existed as observable pressure at the first point; it being, so to
speak, rendered latent, or resulting only in motion at that point. When
the indication of the gauge is negative, or when the barometrical
compression of the air is less at the first than at the second point of
observation, the amount of negative indications will be increased from
the cause under consideration. (65.) Adopting the following notation :—
Z>0=the height required in an air-column of some standard density, (say
that of the average of the air in the downcast shaft,) so that the
pressure per unit of surface of area, produced by its weight, may be
exactly equal to that produced by the actual downcast column of air, on
equal areas; including, in such downcast column, the depth of the
downcast shaft, and also, (when the top of the upcast shaft is situated
at a higher level than the top of the downcast shaft,) the column of air
extending upwards, from the Vol. III.—Dec, 1854.
y
158
top of the downcast shaft to the level of the top of the upcast shaft.
?70=the length in feet, required in a vertical column of air, of the
density adopted as a standard, that it may be capable, by its weight, of
producing a pressure equal to that arising from the upcast column of
air, on equal areas; including, in the upcast column, not only the air
in the upcast shaft, but also, (when the top of the downcast shaft
happens to be situated at a higher level than the top of the upcast,)
the column of air extending upwards, from the top of the upcast shaft to
the level of the top-of the downcast shaft. Di=the head of air-column,
of standard density, equal to the production of pressure, of the same
amount on equal areas, as that arising from all the descending parts of
the air-way extending from the bottom of the downcast shaft to the
first point of _ observation. Z7x=the head of air-column, of standard
density, due to the ascending parts of the air-way extending from the
bottom of the downcast shaft to the first point of observation. Z)2=the
head of air-column, due to the pressures arising from the gravitation of
the air in the descending parts of the air-way, extending from the first
point to the second point of observation. Z78=the head of air-column, of
standard density, equal to the pressure arising from the gravitation of
the air in the ascending parts of the air-way extending from the first
to the second point of observation. J?3=the head of air-column, of
standard density, capable of producing, by its weight, a pressure on
equal areas, of the same amount as that due to the gravitation of the
air in the descending parts of the air-way extending from the second
point of observation to the bottom of the upcast shaft. £7"5=the head of
air-column, of standard density, capable of producing, by its weight, a
pressure of the same amount, on equal areas, with that arising from the
gravitation of the air in all the ascending parts of the air-way
extending from the second point of observation to the bottom of the
upcast shaft. The descents and ascents, in all the preceding cases,
being reckoned as they occur in the direction pursued by the circulating
current of air.
The 1st point of observation must be considered as existing at the point
where an unventilated gallery in which a pressure gauge is fixed,
159
joins the air-way on the side nearest to the downcast shaft• and the 2nd
point of observation must be considered as situated at the point where
the opposite end of such unventilated passage joins the air-way, on the
side nearest to the upcast shaft, in all cases where the gauge is used,
in the ordinary way, by being inserted in a stopping* or door situated
in such a passage, extending from the 1st to the 2nd point of
observation; and the areas and velocities, with the pressures required
to generate them, must accordingly be taken as they exist at these
respective points :—and the pressure due to the gravitation of the air
in ascending- and descending parts of the air-way, must, on the same
principle, be considered only as they happen to exist in the air-way
itself, as these arising from the gravitation of the air in ascents and
descents occurring in the unventilated passage, although they will act
upon the gauge, will not affect the pressure required to circulate the
air; and hence, when a gauge is used in such a passage, its indications
will require to be corrected for the effects which may arise from this
source, in order to arrive at the real difference of pressure between
the air at the 1st, and that at the 2nd point of observation : this will
be effected by deducting from any excess of pressure indicated by the
gauge, as existing on the side next to the 1st, over that existing on
the side next to the 2nd point of observation, the pressure arising from
the gravitation of the air in the descents which occur in traversing the
unventilated passage from the 1st towards the 2nd point of observation;
and by adding to such indicated excess, the pressure due to the
gravitation of air in all the ascents occurring in the same direction,
throughout the entire length of the passage. When the gauge indicates an
excess of pressure in favor of the side exposed to the 2nd point of
observation, it will, of course, be necessary to correct its indications
by adding for the descents, and deducting for the ascents, reckoned as
they occur in such passage, in the direction from the 1st towards the
2nd point of observation. Where no such unventilated passage connects
the two points of observation, or is not made use of in determining the
difference of pressure between the two points, of course the corrections
indicated above do not require to be made. px = The height of air
column, of the density taken as a standard, required
to overcome the resistances due to friction, contractions, or angles,
in the downcast shaft. p2 = The height of air column, of standard
density, due to the resistances
of the same character, in the air-way extending from the downcast
shaft to the 1st point of observation.
160
P = The head of air column of standard density, required to overcome the
resistances due to friction, angles, &c, in the portion of air-way under
notice, extending' from the 1st to the 2nd point of observation.
p3 = The head of air column required to overcome the same resistances,
in the air-ways extending from the 2nd point of observation to the
bottom of the upcast shaft.
p4 = The head of air column due to the resistances of the same
character, in the upcast shaft.
ax = The area in superficial feet, of the air-way at the 1st point of
observation.
a2 = The area in superficial feet, of the air-way at the 2nd point of
observation.
A = The area in feet, at the top of the upcast shaft.
B = The head of air column, of standard density, due to the barometrical
pressure at the top of the upcast or downcast shaft; that is, at the top
of the shaft, situated at the highest level.
Q = The cubic feet of air per minute, circulating through the portion of
air-way lying between the two points of observation j the same quantity
of air being presumed to be passing each of the two points of
observation.
According to what is stated in (63), we shall have for the excess of
pressure at the first point of observation, over that existing at the
2nd point of observation,—and when the negative parts exceed the amount
of the positive parts of the expression, the excess will indicate the
pressure by which the air at the 2nd point of observation, exceeds in
compression, that at the 1st point of observation :—
P + U* + 231600 ag """ 2 ~~ 231600 a?............^
(66.) By the same mode of reasoning we find that the absolute
barometrical compression of the air at the first point of observation
will consist of,—
1st. The barometrical compression of the air at the top of the higher
of the two pit tops, the upcast or the downcast. 2nd. The gravitation of
the air in the downcast shaft. 3rd. The gravitation of the air in the
descending parts of the air-way
extending from the bottom of the downcast shaft to the first point
of observation.
The sum of the above would however require to be reduced by,
161
1st. The resistances of a frictional character, angles, and
contractions, in the downcast shaft.
2nd. The same kind of resistances in the air-ways extending from the
bottom of the downcast shaft to the first point of observation.
3rd. The gravitation of the air in all the ascending parts of the
airway, from the bottom of the downcast shaft to the first point of
observation.
4th. The pressure absorbed by, or resulting in, the production of motion
at the first point of observation; it being supposed to start from a
state of rest at the top of the downcast shaft.
The pressure at the first point of observation will therefore be
expressed by,
* + 2>. +A-R-R-Di-jngj,..............m
(67.) By considering the same principles which have been recited and
applied to determine the expressions [96] and [97]; but in the opposite
direction, commencing at the top of the upcast shaft j we shall have for
the absolute barometrical compression of the air at the second point of
observation •—
1st. The barometrical compression of the air at the level of the top of
the higher of the two pit tops.
2nd. The pressure, in an air-column of standard density, due to the
upcast column of air, from the level of the plane in which the higher of
the two pit tops is situated, to the bottom of the upcast; shaft.
3rd. The pressure in an air-column, equal to the gravitation of the air
in all the ascents made by it, in the air-ways extending from the second
point of observation to the bottom of the upcast shaft.
4th. The air-column due to all the resistances in the air-way extending
from the 2nd point of observation to the bottom of the upcast shaft.
5th. The air-column due to the resistances in the upcast shaft.
6th. The air-column due to the final velocity at the top of the upcast
shaft. But reductions will require making, for,
1st. The velocity of the air at the second point of observation.
2nd. The gravitation of the air in all the descending parts of the air
way traversed by the air after passing the second point of observation,
and before reaching the bottom of the upcast shaft.
162
This absolute pressure of the air at the second point of observation,
will therefore be expressed by,
Q2 Q2
B + UQ + Us + p3 + p4 + 231600 A8 ~ 281600 aS ~~ B* "" [98]
(68.) The difference found by deducting this pressure at the second
point of observation, from that already found as existing- at the first
point of observation, should leave the excess of pressure, (the same as
[96]), at the first, over that at the second point of observation ; the
difference in question, found by deducting* [98] from [97], is
DQ + A - Pl - P3 - TTX - gg-gg- - UQ - U3
- p3 - Pi
Qa Q2 "231600 A3 231600 a* +
Ba..........................W9)
And this expression is, as above stated, equal to [96], or,
D0 + A-Pi-P2- Ui~231600aa~ U°~ Uz~Ps~p*~231600A2 +
—51— + A = P+ Ua + —^—L A-------5!--------[100]
231600a! 231600 a! 3
231600 &* L
from whence we derive the equation,
(DQ + A + A + BO = (U0 + Ux + U2 + U3) + Pl + p2 + P +
P« + & + 231600 Aa ................................f101]
An equation shewing" that the pressure arising- from all the descending*
columns of air, is exactly equal to the total expenditure of pressure
employed in overcoming- the gravitation of all the ascending- columns of
air, together with the factional resistances in the shafts and air-ways,
and in finally ejecting- the air from the top of the upcast shaft; when
the air has been presumed to commence from a state of rest at the top of
the downcast shaft: an equation which strongly indicates the correctness
of the reasoning- which has been followed in obtaining- it.
(69.) On examining- [96], which expresses the excess of pressure at the
1st point of observation, over that existing- at the 2nd point of
observation,
Q2 it will be seen, that when the excess is positive, and P+ ?73 + 0
^
rSoLouv a2
really exceeds the negative part of the expression A + OQ1.An 2,
the
JdluOO 2LX
displacement of the gaug-e fluid, or difference of pressure between the
two points of observation, will be an exact measure of the excess of the
resistances arising from friction, angles, and contractions, together
with
163
the pressure required to overcome the gravitation of the air in the
ascending parts of the air-way lying between the two points of
observation, and to generate the velocity with which the air is driven
past the 2nd point of observation, over the pressure arising from the
gravitation of the air in the descending parts of the air-way lying
between the 1st and 2nd points of observation, added to the pressure due
to the generation of the velocity with which the air reaches the 1st
point of observation:— in other words, the difference of pressure
between the two points of observation, when positive, in favor of the
1st point of observation, is an indication of the excess of expenditure
of pressure, in the air-way extending from the 1st to tlu 2nd point of
observation, upon resistances and motion, over that arising* in the same
part of the air-way, both from the pressure due to the initial velocity
with which the air enters upon it, and from the gravitation of the air
in favor of ventilation, in the descending parts of the air-way itself.
(70.) When the excess is in favor of the 2nd point of observation, the
negative indications of the gauge, or barometrical differences, will, on
the other hand, be an exact measure of the excess of the pressure or
momentum, due to the initial velocity, and the gravitation of the air in
the descending parts of the air-way lying between the 1st and 2nd point
of observation, over the expenditure of pressure in the same part of the
airway, both upon the resistances of friction, angles, and contractions,
and also upon propelling the air up the ascending parts of such air-way,
and fnally ejecting it into the air-way lying beyond the 2nd point of
observation.
(71.) The foreg-oing is an explanation of the indications of a
pressure-gaug*e, as to the differences of pressure existing- at any two
points in an air-way, in reference to the air-way lying* between the
points only. In order to see the meaning* of these indications, in
reference to the shafts and the other portions of the air-ways,
extending from the bottom of the downcast shaft to the first point of
observation, and from the second point of observation to the bottom of
the upcast shaft, it is only necessary to examine [99], which is an
expression of the same value as [96], which we have just been
considering* • each representing* the difference of pressure between the
two points of observation.
The positive items in [99] consist of
/•, + A + A + ^gj^
and the negative items of
161
Q2 Q"5
Pi + ft + Ps + P* + Uo + K+ Us + ggigg^ + 231600 A9
and when the difference of pressure between the two points is positive,
in favour of the first point of observation, the former exceed the
latter, the pressure indicated being-, in fact, an exact measure of the
excess of force or pressure arising- in the descending parts of the
shafts, and airways lying between them and the points of observation,
together with that due to the velocity with which the air enters upon
that portion of such air-ways which extend outwards from the second
point of observation towards the bottom of the upcast shaft, over that
which is due to the resistances of friction, angles, and contractions,
and to the gravitation of the air in all the ascending parts, of the
downcast shaft, and air-ways extending from it to the first point of
observation; and also in those extending from the second to the upcast
shaft, and in the upcast shaft itself; together with the expenditure of
pressure on ejecting the air from the air-way, at the first point of
observation, into the air-way lying between the two points of
observation, and again into the atmosphere at the top of the upcast
shaft. The descents and ascents being reckoned as they occur in the
direction in which the current of air flows, the air being- supposed to
enter the downcast shaft from a state of rest; because, if the air
entered the downcast shaft with a velocity arising from winds, the
pressure due to its generation would require to be added to the positive
parts of the expression.
(72.) When the pressure is greater at the second than at the first point
of observation, the indications of a gauge will be negative, and the
excess of pressure indicated will be a measure of the excess of the
pressure due to friction, angles, and contractions, and expended on
overcoming the gravitation of the air, in the ascending parts, of the
downcast shaft and the air-ways extending from it to the first point of
observation, and in those extending from the second point of observation
to the bottom of the upcast shaft, and also in the upcast shaft itself;
together with the expenditure of pressure on creating both the velocity
at the first point of observation, and also that with rvhich the air
leaves the top of the upcast shaft, over the pressures due to or arising
from the gravitation of the air in the descending parts of the shafts
and air-ways above alluded to, together with that arising from the
momentum with which the air enters upon the air-way extending from the
second point of observation outwards, to the bottom of the upcast shaft.
(73.) In general terms the indications of pressure given by a water or
105
other similar pressure-gauge connecting- the two points of observation,
(after being corrected, if necessary, for the gravitation of the air, in
any ascents and descents in an unventilated passage, wherein it is
fixed,) have the same meaning- and amount as the differences of
barometical pressure of the air at the two points of observation, of
which they are the true measure j and when the excess prevails at the
first point of observation, which will always be the case when the
intermediate air-ways are horizontal, this excess is equal to the excess
of the force or pressure expended, over that generated or arising, in
the air-ways extending from the first to the second point of
observation; and, at the same time, it is a measure of the excess of
force or pressure arising, over that which is expended, in the shafts
and other air-ways lying between them and the points of observation.
But, on the contrary, when it happens that the excess indicated is in
favour of the second point of observation, or what may be termed
negative, then it is a measure of the excess of the force or pressure
arising or generated, over that which is expended, in the airways lying
between the points of observation; and, at the same time, it is also a
correct indication of the excess of the force or pressure expended, over
that which arises or is generated, in the shafts and in the air-ways
¦extending between them and the respective points of observation.
Having- now determined the real meaning' or indications denoted by the
displacement of a gauge fluid, or by the differences of barometrical
pressures existing in different parts of an air-way, whether such excess
exists at the first or at the second point of observation; and that,
both in reference to the air-ways lying* between the two points of
observation, and again, in reference to the shafts, and the other or
remaining- air-ways, extending- from them to the respective points of
observation, we shall proceed to make some general remarks on the
qualities required in instruments for determining the quantities of air,
and also in those for determining the differences of barometrical
pressure, regretting-, however, that good instruments, for the latter
purpose in particular, still appear to -remain a desideratum, rather
than a thing which has been realized— -even after the remarks and
suggestions about to be offered.
Wol. TIL, Dec., 1854, x
166
CHAPTER VII.
Remarks on certain Instruments used for tolling Observations relating to
the Ventilation of Mines—Formulce for converting Pressures— Table of the
Tension of Aqueous Vapour.
(74.) The anemometer of Mr. Biram, which is now much used for measuring
the velocity of currents of air in mines, like that of Mr. Combes, is,
when well constructed, a very useful instrument. These instruments,
however, are affected by friction, so that the number of revolutions in
a given time are not proportional to the velocity of the air; and, in
fact, are so much affected by it, that in slow currents they may not
revolve at all, and become inapplicable in consequence.
The velocity of any current of air, acting- upon either of these
instruments, will be determined by the use of a formula, of the form of
v = a + bn ......................[102]
where v = the velocity of the current of air, and a and b are constants,
suited to the particular instrument; for, although they are different in
different instruments, yet are they each constant, for the same
instrument, whatever may be the velocity of the current.
The constants a and b can be determined for any instrument by means of
two experimental trials of the number of revolutions corresponding to
different velocities: thus if v and n are the velocity, and
corresponding revolutions in a unit of time, in one of such trials; and
vx and nv the same, respectively, in the other trial; then, since
v = a + bn and vv = a + bnx
it follows that,
b = v ~ v' ..........-........[103]
n — nN L
and
a:=n7-DvV ..................[104]
n' — n u
167
In these experiments, instead of exposing the instrument to moving air,
the air may be still, and the instrument itself put in motion, at some
determinate velocity, by machinery• this is the mode pursued on the
Continent in constructing the, anemometer of Mons. Combes; the values of
the constants a and b being furnished to the purchaser of each
instrument. Whenever the velocity is less than the constant a, these
instruments do not revolve, and cannot be used for determining the
velocity of a current of air in consequence.
(75.) The anemometer of Dr. Lind is very similar in construction to an
ordinary water-gaug'e, but has a wide mouth-piece attached to one of the
vertical limbs of the |J shaped tube, to receive the impact of the
current of air; and the force of the wind is measured by the difference
of the level of the water, in the two branches of the tube• the
undulations of the water being, to some extent, reduced by a contracted
portion of tube, which connects the two vertical branches.
This instrument is good in principle, as it is not affected by friction,
and is easily applied to determine the force of winds, whether
horizontal, vertical, or inclined, in the direction of their motion; and
that without involving* any measurement of time, as the velocity can be
calculated directly from the force or impact of the air; the instrument,
however, will seldom apply to such currents as exist in mines, it not
being sufficiently sensitive; a velocity of 1 foot per second, or 60
feet per minute, would only give a displacement of l-2,756th part of an
"inch in the water-column; and even 4 feet per second, or 240 feet per
minute, would only produce a displacement of 1-172nd part of an inch of
water-column-while a velocity of current equal to 1,000 feet per minute,
such as prevails in some upcast shafts, would only produce a pressure oi
about one-tenth of an inch of water-column; the mere variations in
velocity, being-indicated by variations in so short a column, would, of
course, be scarcely discernable on the scale of such an instrument.
(76.) The loss of pressure due to the resistances offered hj the airways
of a mine has frequently, of late years, been determined by the use of
the now well-known instrument called the water-gauge. The entire
resistances of the workings seldom giving a displacement of more than 2
inches of water-column; any slight variations in such a quantity being
too small for easy and correct measurement; an evil which ao-ain becomes
greater, as the portion of air-ways to which it is applied, are of less
extent and resistance; and such an instrument is, from its very nature,
totally inapplicable to measure the resistance of a mine, when the
168
nfiafts are situated at a great distance apart, and are not connected'
by any unventilated passage, in which to fix the instrument; and it is
equally inapplicable to the measurement of the resistances of any
air-way, or part of an air-way, the extremities of which are situated at
a distance from each other, and not connected by any unventilated
passage, contain*-ing a separation door or stopping, in which to apply
it.
Having paid some attention to this subject, in hopes of devising an
instrument which would enable us to observe the resistances of air-ways
under all circumstances, 1 venture to throw out suggestions, which if
not satisfactory in all respects, may at any rate be of service to
others,: who may more successfully attempt the same thing.
(77.) "An instrument is named by Dr. lire, in his "Dictionary of Arts,
Manufactures, and Mines," under the article "Chimney,"' which
he-ascribes to Wollaston, as being invented by him, to be used, as a
differential barometer; and which Dr. Ure adopted for measuring the
draughts or ventilating power of furnaces.
A modification of this instrument, or what I presume to-be such, (for it
is only partially described by Dr. Ure, and I have not seen Wollaston's
description of it,) would appear to furnish a very sensitive
pressure-gauge, to be used instead of the ordinary water-gauge; and
might, perhaps, also admit of being applied to measure the loss of
pressure due to. resistances of air-ways, or portions of air-way, having
their extremities totally unconnected by any unventilated gallery.
In Plate 1, figures 1 and 2, let a, b, c, d, represent a metallic
air-tight box, with an air-tight diaphragm, e, f, dividing it into two
equal parts, communicating with each other by means of the small pipe gr
with a stop-cock h in it; the compartment of the vessel e, b, f, d, has
a pipe, b, k, with a stop-cock, i, attached to it; and the other
compartment of the metallic vessel, a, e, c, f, has a similar pipe, m,
a, with a stop-cock,, 1, attached to it. A brass or copper tube, q, p,
o, w,, having a stop-cock at n, is fixed air-tight into the vessel at q;
and. a glass tube, v, w, is fixed, air-tight, into the tube at w; and
its opposite end is similarly fixed into the other compartment of the
vessel at v. The two side tubes are "screwed" atm, and k. A scale,
divided into inches and tenths, is attached to the glass tube: m, g,
k,.is one continuous tube.
If water, of the specific gravity of 1,000, be introduced through the
side tube, k, b; while the cock, n, is kept closed; and if some oil of a
pure character, having a known dersity, not greatly differing from that
of water,, be introduced through in, a, into the other leg of the bent
tube.
169
and the cock, n, be opened, and more oil or water be added, till the
junction line of the oil and mater stands at, or somewhere above zero,
(z), on the scale, then the instrument is ready for use.
To use this instrument as a gauge, in lieu of the ordinary water-gauge,
close all the stop-cocks, 1, h, i, and n, and attach the instrument, by
means of a small gutta percha tube, screwed, or otherwise fixed to k, or
m, to a tube inserted in a door or stopping, separating the intake air
from the return air; then bring the instrument into a perfectly vertical
position, either by having it swung in gimbals, or by means of small
spirit levels,, attached to, and forming a part of the instrument; and
open the cocks n, and h, while i, and 1, remain closed; note the part of
the scale where the-junction of the oil and wrater rests, and afterwards
open the cocks i, and J, and close h, and again note the part of the
fixed scale where the junction of the oil and water rests.
The difference of the two observations will furnish the means of
determining the difference of pressure, on the two sides of the door or
stopping, in which the instrument is used; and hence, also, of the
resistances of the air-ways, traversed by the air after passing the
intake side of the door or stopping, and before reaching the contrary
side of it. The stop-cock, n, will be useful in carrying the instrument,
to prevent the oil from getting into the water tube, and so ascending to
the top of it; and will, by being only partially opened when the
instrument is in use, tend to prevent undulations of the fluids, from
temporary disturbances of the pressures to which they are exposed.
Let r = the distance in inches, traversed by the junction line of the
oil and water.
a = area of the glass tube, traversed by the junction of oil and water.
A = the area of each of the equal compartments, into which the metallic
vessel is divided.
s = specific gravity of the oil used.
S = .... do. .... of the water used.
Then the pressure in inches of water column, arising from the movement
of the fluids will be,
In the vertical tube of glass, r (S—s).-r S ;
In the oil compartment, r — s -— S;
A
a In the water compartment, r — S ¦— S.
iro
The entire pressure creating the movement, (being the sum of the above,)
will be expressed by
( (S-s)+ x(S + s)\ G=v[--------------A-----------j
................[105]
where G represents the pressure in inches of water column ; and hence,
r - _______§-?______........................[106]
S-s + -j- (S + s)
so that if we suppose the oil used, to be refined linseed oil, having a
specific gravity of 940, that of water being 1,000 ; and the area of the
vessel to be 729 times that of the glass tube, or each compartment to be
364J times the area of the glass tube; which would be the case if the
metallic vessel had a diameter of about 9 inches, while that of the
glass tube is taken at J of an inch, both the metallic vessel and tube
being supposed to be cylindrical, or having circular sections.
Then, an inch of water-gauge would be represented by a rise equal to
r =_________imx^________= i5.3087
1000-940 + -—— (1000 + 940) do*£
inches in such an instrument; so that it would have a scale upwards of
15 times as long as that of a water-gauge, to represent equal pressures.
If, in such an instrument as has just been described, a small vertical
strip of glass were cemented into the metallic vessel, so as to shew the
height of the surfaces of the oil on one side of the diaphragm, and of
the water in the other compartment of the vessel, and if this glass were
divided into inches and tenths, in continuation upwards, of the scale
before alluded to, it would enable us to determine the relative
densities of the oil and water, employed in using the instrument; and
would be also serviceable in enabling the actual volume of enclosed air,
contained in the vessel, to be ascertained j which will be required if
the instrument should be used in the manner hereafter to be explained,
for determining the difference of pressure, prevailing at parts of an
air-way situated at distances apart from each other, and unconnected by
any unventilated air-way, so as to prevent the use of the instrument in
the form in which the ordinary water-gauge is used.
Such a strip of glass is represented in the figures by e, f.
To determine the relative specific gravities of any oil and water made
use of, it would only be necessary to bring the instrument into a
vertical
171
position, and to open the stop-cocks n and h, allowing those at k and 1,
to remain closed; and then to observe the point of the scale at or above
zero, where the junction of the oil and water rests, aud also the two
points on the strip of glass, (forming a part of the sides of the upper
metallic vessel, and the continuation of the scale upwards,) at which
the surfaces of the oil and water, respectively rest. Then by deducting
the height of the point of junction of the oil and water, above zero on
the scale, from the height of the surface of the water, above the same
zero, we shall have the length of water column which is equal to that of
an oil column; the height of which will be found, in like manner, by
deducting the height from zero of the scale to the line of junction of
the oil and water, from the height at which the surface of the oil rests
above zero of the scale. The lengths of the columns of water and oil, so
found, since they exactly balance each other, will be inversely
proportional to the specific gravities of the liquids of which they
consist.
If by J, we represent the height above zero, at which the junction of
the oil and water rests; by W, the height above the same point, at which
the surface of the water rests; and by O, the height, also above the
same point, at which the surface of the oil rests; by S, the specific
gravity of the water, and by s, that of the oil employed; then,
As S : s :: O — J ; W — J
and hence the specific gravity of the oil,
W —J
s = s-rb~r.....................[107]
In such an instrument as that described, if the length of the glass tube
above zero on the scale were (15-3087 x 2) = 31 inches, nearly; it
would, by using oil of the specific gravity 940, measure a difference of
pressure, equal to 2 inches of water-column, and be upwards of 15 times
as sensitive as the ordinary water-gauge:—and by using oil of less
specific gravity, in an instrument of greater length, of course greater
differences of pressure could be determined, with even greater accuracy.
The instrument described might be used after the manner of Lind's
anemometer, to measure the velocity of currents of air, by adapting a
trumpet-mouthed gutta percha tube to the side tubes, m, or k, to receive
the impulse of the wind :—but, for currents of less than 7 feet per
second, or 420 feet per minute, it can scarcely be considered
sufficiently sensitive; at least the displacement of the line of
junction, would, for any such currents, be very small in amount;
although it would, where applicable, have the advantage of being
unaffected by friction, and not being- confined
172
to horizontal currents, nor requiring the measurement of time; the
velocity being deduced directly from the force of the wind, in direct
impact; and it would he upwards of 15 times as sensitive as Lind's
anemometer, if made of the dimensions before alluded to, and oil of
specific gravity
940 were used.
Dr. Ure suggests that by the use of proof spirit, and spermaceti oil, in
such instruments ; a great degree of sensitiveness may be obtained, as
they are so nearly of the same specific gravity. As the water and oil
displace each other, by any motion of the point of junction, the actual
pressure is represented by a fluid, having a specific gravity only equal
to the difference of the specific gravities of the fluids used; at any
rate, so far as regards the distance traversed by the point of junction
of the water and oil:—there being a reduction to be made from this
degree of sensitiveness, owing to the motion of the surfaces of the
fluids in the metallic vessel at the top of the instrument just
described ; but as the areas of the surfaces in question, are, or may
be, some hundreds of times greater than the area of the glass tube in
which the junction line of the fluids moves, their effects are
proportionably reduced.
The contrivance of an instrument of great sensibility for determining
the minute differences of absolute barometrical pressure prevailing at
two points of an air-way, when such points are not so situated as to
admit of the direct measurement of such difference of pressure, either
by a water, or other more sensitive pressure-gauge, appears to remain a
desideratum.
An instrument intended to effect a similar object to this, recently
brought under notice by Mr. Gurney, appears to me to be open to the
objection, that, while it requires very great corrections for the
effects of heat, its peculiar construction renders it very difficult to
apply such
corrections.
Another, mentioned by Mr. Mackworth, the Inspector of Mines, is not
sufficiently explained in the account which has come under my
observation, to warrant me in giving any opinion as to its merits ; but
such an instrument, seeing that it would be likely to supersede the
common barometer, if of a portable character, and free from requiring
the application of corrections for heat, leads me to fear that it is
objectionable on the same account. Various kinds of contrivances are
described in llutton's Philosophical Dictionary, and other works of a
similar character, for increasing the scale on which changes of
barometrical pressure are indicated; but all that I have yet seen, and I
am sorry to add all that I
173
can yet imagine, are liable to one or other of the objections, want of
portability, or the necessity of very great corrections for the effects
of heat.
(78.) As an addition to the general stock of such suggestions or
contrivances, I think it worth while noticing the manner in which the
instrument to which I have just alluded might be made use of for
determining very minute differences of barometrical pressure; and
although requiring very great corrections for the effects of heat, it
appears to be at least capable of admitting the application of such
corrections, with very great nicety. Possibly the suggestion may lead
some one else to another, and more effectual mode, of attaining the same
object.
In order to determine the difference of barometrical pressure,
prevailing at any two points of an air-way, so situated with respect to
each other, as not to admit of such difference of pressure being
determined by the ordinary use of the water, or differential
pressure-gauge; we may proceed as follows:—
Take the oil and water-guage to one of the two points, which we shall
distinguish from the other by calling it the first station, or the first
point of observation; and fix the instrument in a perfectly vertical
position, and after opening the stop-cocks n, 1, and i, bring the
junction line of the oil and water in the glass tube to a position about
half-way up the scale, by introducing or abstracting, oil or water, if
found necessary j after allowing the instrument to acquire the
temperature of the surrounding air, make and note down the following
observations, which we will here denote by the respective letters
prefixed to them,—
t° = The temperature of the air at the first station; which may be taken
either by a thermometer attached to the instrument, or a separate one.
p = The barometrical pressure of the atmosphere, reduced to inches of
water-column; which may be observed either by a sympiesometer, or a
mercurial, or aneroid barometer.
b = The number of cubic inches of air existing in the water compartment
of the metallic vessel at the top of the instrument. The area of a
horizontal section of this compartment being A, it will be necessary, in
order to find this, to multiply such area, in inches, by the distance in
inches, from the top of the vessel to the surface of the water; which
can be observed by means of the scale of inches and parts, to be marked
on the strip of glass, fixed vertically into, and forming a part of the
side of the vessel.
Vol. III.—Dec, 1854. a a
174
If the relative specific gravities of the oil and water are not known,
it will also be necessary to make a similar observation with reference
to the surface of the oil, and by [107], the specific gravity of the oil
will be found, h = The height above zero of the scale, in inches and
parts, at which the junction line of the oil and water stands in the
glass tube. Previous to making this observation, it would, perhaps,
be well, partially to close the stop-cock, i, so as to ensure the
enclosed air being saturated with the vapour of the water, due to the
existing temperature. Also let f = The tension of watery vapour, due to
the temperature t°, when saturated ; expressed in inches of
water-column, which can be found from tables, hereafter to be
given—next, gently close the stop-cock, i, so as not to move the
junction line of the oil and water in doing so, and also close the
stop-cocks, 1, and n; and proceed with the instrument, in this state, to
the second point of observation ; on reaching which, the instrument must
be allowed to acquire the temperature of the surrounding air, and then,
when in a perfectly vertical position, the stop-cocks, 1, and n, must be
opened; i and h remaining closed; the air, thus being admitted to the
surface of the oil, will allow the confined air over the water, to
expand, or cause it to contract, so as to establish an equilibrium of
pressures; the amount of such expansion, or contraction, will be found
from the movement of the junction line of the oil and water in the glass
tube. At the second station it will be necessary to observe, and note
down, the following quantities, which we will denote by the symbols
prefixed to them : tv = The temperature of the air.
h* = The distance in inches and parts, as shown by the fixed scale, from
zero to the junction line of the oil and water, in the glass tube, the
area of which is a. Also let p( = The pressure of the atmosphere at
the second station; and f = The tension of watery vapour, saturated, at
temperature tx
On referring to [105], it will be seen that the tension of the mixture
of air and watery vapour, at the second station, after opening the cock
1, will be
^+(V-h)[--------^-------j
the tension of the confined air, at the second station, will be; see
(33),
175
p< + (hi _h)[-----------^----------J- f
The pressure of the air and watery vapour, at the first station, is
expressed by p j the tension of the confined air only, at the same
point, being p — f. Now, since the volume assumed by the enclosed air,
exclusive of the vapour mixed with it, which may vary; is directly
proportional to the sum of the temperature, and the constant number 459
; and at the same time, inversely to the tension or pressure j we have,
P,+(h.-h)(b-3+f^>)_r
from whence comes the equation,
. (459 + t;)(p--f)b Js-S+X(s+S))lfx n08l
P -f459 + t°){b+(h* -h)a}-<h -hH-------g-------/+f "[108J
by means of which, after taking the observations which have been stated,
the pressure of the atmosphere at the second point of observation, can
be calculated, in such a manner, as, that any error which may have
arisen in determining the atmospheric pressure, by a barometer or
sym-piesometer, at the first station, will be sensibly the same in
amount here, so that by taking the difference
when p^ is determined as above, we shall obtain, to great nicety, the
excess of pressure at one station, over that at the other.
It will, of course, be desirable to make the observations at the two
points as quickly after each other as may be, and even to repeat them
more than once, so that no error may arise from altered conditions of
atmospheric pressure, or in the loss by resistance, owing to a change in
the quantity of air circulating at the times of observation.
Having thus determined the difference of pressure, between the two
points in the air-way, and observed the quantity of air circulating at
the times of observing such difference, it remains to calculate the
effects of the gravitation of the air in the ascending and descending
parts of the intermediate air-way; these, being separated from the
total, will, if all has been correct, always leave an excess of
pressure, as existing at that point of observation from which the air
commences to traverse the airway under notice, over that existing at the
opposite end, by which the
170
air leaves the air-way under notice; and this excess is the actual
expenditure of pressure on the other resistances of the intervening*
air-way, (excluding the effects of gravitation only), when the ohserved
quantity of air is circulating* through it*, and hy [57] or [60], we can
therefrom determine the specific resistance of such intermediate
air-way; only
r *p __i ^
using the difference of pressure in lieu of D0 — UQ, or d < ^q ^ - >
When h is greater than h^ , owing to the air contracting at the second
station, the value of (hv — h) will, of course, be negative; hut the
formula} given will apply with the same accuracy, as in the opposite
case.
(79.) As was intimated, the great inconvenience attending- the use of
such an instrument, would be, that the expansion of the confined air, by
heat, would cause an immense change in the volume of air, and so require
the scale to be very long; or, on the other hand, the total quantity of
confined air would require to be so small, as to render the instrument
little, or perhaps no more sensitive than the ordinary water-gauge. At
ordinary temperatures 1° of Fahrenheit would, if added to the
temperature of the confined air, expand its -volume, nearly as much as
an inch of water-pressure would do, by being* removed.
To remedy the evil complained of, the instrument might, at the times of
making* the observations, be immersed in a tall glass vessel containing*
a mixture of water and melting ice, (excepting only the mouth of the
tubes projecting from the sides of the metallic vessel, which might
project upwards), so as to ensure the temperature of the vessel and its
contents, being* 32°; and although this would be rather a troublesome
process, it would render any observations of temperature needless, would
simplify the formula? for finding the difference of pressure, save all
reference to tables of the tension of watery vapour, and admit of the
instrument being* made very much more sensitive than an ordinary
water-gauge; by enlarging the metallic vessel, without making the scale
of the instrument very long. According to Magnus, the tension of watery
vapour at 32° is -178,62 inches of mercury ; and according to Regnault
it is -181,58 inches, the density of the mercury being that due to a
temperature of 60°, and adopting the average, it is equal to -180,1
inches of such mercury, or 2*442,15 inches of water; which, in this
case, will, therefore, be the value of f, and also of fv , and the
formula will become
p- -&&m^ _h)(S-s+>+8))+3.M[iog]
177
If, therefore, in such case, p = 402*44; b = 249*9; hx = 30 and
h = 29; a = -—; S = 1000; s = 040; and A = 40; we shall find
that p* = 402*215,15; so that a difference of actual pressure equal to
•224,85 inches of water-column, would be indicated by a movement of the
junction line, over 1 inch of the scale, the instrument being 4| times
as sensitive as a water-gauge.
(80.) In order to convert any pressure per unit of surface expressed in
feet of air column, into the same, when expressed in inches of
water-column ; or the reverse ; since the weight of a cubic foot of air
is expressed, [43], in B5s., by
1*3244 f
w = --------------
459 + t
and the weight of a cubic foot of water at 62°, and 30 inches
barometrical pressure, is 62*32102 lbs. avoirdupoise; and since the
heights required, for the production of equal pressures per unit of
surface, must be inversely as the densities of the fluids composing
them; if by I, we represent the height of a column of water in inches,
and by H the height of a column of air in feet, capable of producing the
same pressure, we have,
1 •ao44 f t
As 62*32102: ^ * * :: H : — 459 + t 12
and hence,
I-^fH ...........................[noj
459+ t and,
H - 8'92133 I (459 + t) rm-|
by which these conversions can be effected; they may occur in
calculations regarding ventilation.
(81.) In order to convert any pressure per unit of surface, expressed in
inches of mercury, into the same pressure, expressed in inches of
water-column, we obtain the rule by taking into consideration, that at
32° the specific gravity of mercury is 13,598, that of water being
1,000; and that mercury has been found to expand l-9,958th part of its
volume at zero of Fahrenheit's scale, for each degree of heat imparted
to it, so that its density at any temperature t, will be found by the
expression,
178
13,598 x (9,958 + 32) 9,958 + t
to that of water, taken as 1,000. And since the heights required, in
columns of different densities, to produce equal pressures, are
inversely proportional to such densities; we have,
. 13,598 x (9,958 + 32) >g 9,958 + t where B is the inches of mercury,
and I the inches of water; giving,
135,844B...................... }
9,958 + t L J
and,
_ (9,958 + t) I...........................[113]
u - 135,844 L J
By making the two values of I in [110] and [112], respectively, equal to
each other, a formula could he obtained for converting an air, or a
mercurial column, into a column of the other, of equal pressure; the
former expressed in feet, and the latter in inches—these formulae,
however, are based on the assumption of the air-column being homogeneous
throughout its extent, and the same as at the point of observation j
this being what is wanted for application in most of the formulae given
in this memoir.
(82.) It may not, perhaps, be out of place to notice here, that, if by v
we denote the velocity of a wind, in feet per minute; and by I, the
inches of water-column, supported by the impulse of the wind j then, by
Hutton's experiments,
I =-----1-------.............................[1141
9,921,600 L J
and
v = 3150VT~..............................[115]
Other writers give rules, based upon different experiments from those of
Hutton, which give greater forces, for equal velocities, than the above
formulae, which I have constructed to agree with Hutton's experiments.
Indeed, Borda's experiments give pressures about one-third greater than
those made by Hutton, for equal velocities.
Since the weight in lbs. of a cubic foot of air is expressed by
1-3244 f
w = -----------------------
459 + t
179
the pressure per foot arising from a column of air, H feet high, will
be,
1-3244 f H P 459 + t
where p is the pressure in lbs. per foot; and we will find the height of
air column, required to produce any given pressure, by,
H_ (459 + t) p 1-3244 f
(83.) Experiments have been made by Dalton, and also by TJre, in
England; and by Magnus, and also by Eegnault, on the Continent, to
determine the tension of aqueous vapour at different temperatures; and
as the results of Magnus agree very closely with those of Eegnault, I
have deemed it worth while reducing their results, from tables where the
temperatures are given in degrees of the Centigrade thermometer, and the
corresponding tensions in millimetres of mercury, of the density due to
0° Centigrade; into temperatures expressed in degrees of Fahrenheit's
thermometer, and corresponding tensions expressed in inches of mercury
of the density due to a temperature of 60° of Fahrenheit's thermometer;
and I have also given the tensions, as contained in the tables by Dalton
and Ure.
In using the table for the preceding calculations it will, in general,
be desirable to adopt and adhere to the results of one particular
authority, so that the discrepancies may effect the results as little as
may be.
»-i_i_i,_i,_itOtOtOtO
6©6db 6 t« >d 6 6 ds 6 6 ob 6 6 to d os ob 6 to id 6ob 6
to d csoo o to ^ ^ wo oo os #» to © co o k> to o oo cs
o.ooooooooooooopopppppo
?J. >^i^i^i^i^^i-Ji^66666666o6ooo
CO • ^OOIlliWWMOOfflOOSvlOSOaiOiiM^WM
tO- !DO*-UMUl|iOia)OtO^HOlOOlHStO!BO)
o oooooooooooooooooooooppooooooopoo
1 l^i . mhhmhm^mOOOOOOOOOOOOOOOOOOOOOOOOO
• CO • OSfflOl*k|flHOOCOOSNSOQOlOl^^OKCOM»M»»KIHMHHi-'-
• Ol • Mv!Ci3O<COOO»0iQ0HaO0lHS»Offl05H(B»lM8O(»S01ll>05Ki
II
o o o o pop
MM M tb tb tO tb
tOM ©CO 00 -^J OS
00 OS Ol I** MMW
to to
Ot if--lO Ol
o o op oo
tb tb to tb tb tb
M to 10 i-1 O O
-<J CO l—' O -Q ©
fej
u
oo
en
** *- OS 00
t0*,&ob K> £
« «, »i d
t-11-1 6 6 6 6
>&¦ o -o ii>. o ~q
o >—
ooo 6 6 oo
o o o o
00 00 O' tO
>— M
CO -Q
© O
Oo OOO OO OO OO
!I? ti CSOSCS ©6 WW o\ Ot
»£2 £^5* M'-' ^^ OS!*-
C>—' 00 © Ol oiffl -^00 OtO
poo o o
!01 OT id d d
to © © -^oi
** -<j o ** 00
(4> *-H> tO
M ©
© © OOO O O
id H> CO M M MM
*— © 00 -s| CS Ot M
Ot I-1 00 Ox M h- CO
182
Temperature. TENSION OP VAPOUR.
Magnus. Regnault. Dal ton. Ure.
87-8 1-321 1-319
88 .... .... 1-28
89 1-32
89-6 1-398 1-396
90 .... .... 1-36 1-300
91 1-40
91-4 1-479 1-477
92 .... .... 1-44
93 1-48
93-2 1-565 1-562
94 .... 1-53
95 1-654 1-651 1-58 1-640
96 .... 1-63
96-8 1-748 1-745
97 .... .... 1-68
98 1-74
98-6 1-846 1-843
99 .... 1-80
100 .... 1-86 1-860
100-4 1-949 1-946
101 .... 1-92
102 1-98
102-2 2-057 2-055
103 .... 2-04
104 2-170 2-168 2-11
105 2-18 2-100
105-8 2-289 2-286
106 2-25
107 2-32
107-6 2-413 2-410
108 2-39
109 2-46
109-4 2-542 2-540
110 .... 2-53 2-456
111 .... 2-60
111-2 2-678 2-676
112 .... 2-68
113 2-820 2-819 2-76
114 .... 2-84
114-8 2-968 2-967
115 2 92 2-820
116 300
116-6 3-123 3-123
117 3-08
118 316
118-4 3-285 3-285
119 .... .... 3-25
120 3-33 3-300
120-2 3454 3-455
121 .... 3-42
122 3-631 3-631 3-50
123 .... 3-59
1238 3-815 3-816
124 3-69
125 .... 3-79 3-830
125-6 4-007 4 009
126 .... 3-89
127 .... 4-00
1 127-4 4-207 4-210
183
Tempei ature. . TENSION OP VAPOUR.
Magnus. Regnault. Dalton. Ure.
128 4-11
129 .... .... 4-22
129-2 4-417 4420
130 .... .... 434 4-366
131 4-634 4-638 4-47
132 4-60
132-8 4-861 4-866
133 .... 4-73
134 4-86
134-6 5-097 5-064
135 ---- 5-00 5-070
136 .... 5-14
136-4 5-340 5-350
137 .... 5-29
138 5-44
138-2 5-600 5-607
139 .... .... 5-59
140 5-866 5-875 5-74 5-770
141 5-90
141-8 6-143 6-153
142 .... 6-05
143 .... 6-21
143-6 6.432 6-442
144 6-37
145 145-4 6-732 6-743 6-53 6-600
146 6-70
147 .... 6-87
147-2 7-043 7-055
148 7-05
149 7-367 7-881 7-23
150 150-8 7-704 7-718 7-42 7-530
151 7-61
152 .... • • • > 7-81
152-6 8-053 8069
153 8-01
154 .... 8-20
154-4 8-416 8-433
155 .... 8-40 8-500
156 8-60
156-2 8-793 8-811
157 .... .... 8-81
158 9-183 9-203 9-02
159 .... .... 9-24
159-8 9-589 9-608
160 ---- 9-46 9 600
161 .... 9-68
161-6 10-010 10-031
162 .... 9-91
163 .... 10-15
163-4 10-446 10-468
164 .... .... 10-41
165 .... 10-68 10-800
165-2 10898 10-921
166 10-96
167 11-366 11-391 11-25
168 11-54
168.8 11-852 11-877
169 11-83
170 12-13 12-050
18.r
CHAPTER VIII.
Example of the Application of the Specific Resistances of the Air-ways
of a Mine, for determining the Effects, on the Ventilation of a Mine,
which would be produced by a " Change of Air"
Having shewn how the specific resistances of an air-way, or any portion
of an air-way, may be found by calculation, providing we know the exact
difference of the barometrical pressures, existing at its two
extremities, together with the ascents and descents traversed by the air
in passing from one point to the other, and the temperature of the air
in each part ; it may, at least, serve as a general illustration of many
of the preceding parts of this memoir, to proceed to shew, by an
imaginary case, assumed as an example, how such specific resistances,
when found for all parts of the air-ways of a mine, may be made use of
to determine the particular effects which would be produced on the
ventilation of each part of such mine, by effecting any proposed or
contemplated alteration in the arrangements for ventilating it; in other
words, to shew how a knowledge of such resistances would enable us to
determine the exact quantity of air, which would circulate in each of
the new " splits," under any given or assumed general ventilating
pressure; after making any proposed or contemplated " change of air."
In offering the following example, it is not presumed that the very
troublesome mode which has been suggested for finding the exact amount
of very minute differences of pressure, existing at different points in
an air-way, situated at a distance from each other, is such as to be
likely to be often resorted to; yet it is hoped that such an example, by
calling attention to the use which could be made of a knowledge of such
differences of pressure, may at least have the effect of leading to an
attempt being made to devise some less objectionable method than that
alluded to, for determining with sufficient accuracy, the amount of any
such differences of pressure; as the attainment of this object,
certainly appears, in the abstract, to be quite possible.
186
Supposing- the general features of the ventilation of a coal mine to be
shewn by the figure in Plate 2.
And; for the sake of simplifying the case, let it be presumed that the
entire extent of the air-ways are situated in the same horizontal plane,
so that the pressures and the ventilation are not affected by any
constant forces, arising from the gravitation of the air in ascending or
descending parts of the air-ways.
In the first place, let us suppose the air to be divided into no more
than two distinct currents, represented in Plate 2 by the arrows j the
currents separating at the bottom of the downcast shaft a; one current
passing to the right through b, c, d, over an air-tight crossing at e,
through f, r, g, over the furnace at x, and up the upcast shaft at z¦
the other current leaving the bottom of the downcast shaft at a, and
going' to the left, through under the air-tight crossing at e, thence
through h, i, k, 1, m, n; and joining the first current at g; and, in
connexion with it, going to, and over the furnace at x, and up the
upcast shaft at z.
Let it be presumed that we wish to know what would be the effect on each
part of the ventilation of the mine, if the arrangements were so
altered, as to divide the air in the following manner; on the assumption
of the total ventilating pressure being maintained at the same amount,
after, as before the change—
1st. Let one current, which we shall call No. 1, pass from the bottom of
the downcast shaft, as in Plate 3, through b, c, p, to and over a new
crossing to be placed at q, (the doors on each side of it being
removed,) and thence to x, over the furnace and up the upcast shaft.
2nd. Another current No. 2, being a split from No. 1, which it separates
from at b, goes thence through m, n, g, and so to x, -and up the upcast
shaft; the stopping between b and m being removed. 3rd. Another current,
No. 3, being a split from No. 2, leaving it at m, passing through 1, y,
g, and so to the furnace at x, and up the upcast shaft—the stopping at y
being removed. 4th. Another current, No. 4, dividing from the other air
at the bottom of the downcast shaft, and passing through w, v, d, over
the crossing at e, to f, r, g, and x, and thence up the upcast shaft—
this requiring the removal of the doors near w, and also the placing of
a door or stopping at v. We will also presume the regulator at r to be
removed on changing the air.
187
5th. Another portion of air No. 5, separating from the general body of
air at the bottom of the downcast shaft at a, and passing under the
crossing at e, and thence through h, i, k, y, g and x, and up the upcast
shaft at z—a stopping or door near y being* taken away on making the
change. The following diagram will serve to exhibit the general
connexion existing between the currents after the change has been
effected ;
The dotted lines represent galleries or air-ways not traversed by any
current before the change is effected, but which will be ventilated
after it is effected—while from p to v, on the contrary, will cease to
be ventilated after the change is effected, although previously
ventilated—and hence the specific resistances of these parts will
require to be determined, by taking the dimensions of the air-way, and
calculating* by the formulas which have been given for the purpose, in
another place;—so far, at least, as regards the parts where no air is
circulated before the change; inasmuch as where there is no current
there cannot be any loss of pressure from resistances.
Since we have presumed the workings of the mine to be level, the
specific resistance of the ventilated passages will be found by dividing
the loss of pressure, (expressed in feet of air column, of some density,
assumed as a standard), by the square of the number of cubic feet of air
in circulation per minute; only excepting in the shafts, and it is
presumed that enough has been said to render clear the mode of
proceeding to obtain their resistances ; it only involving, in addition
to the rules for horizontal passages, the necessary allowance for the
weight of the air in them, in certain instances.
A consideration of the diagram just presented, together with the figure
188
in Plate 3; where the arrows denote the route taken by the air after the
change, will shew where observations should be made.
Let it be presumed that we are using an oil and pressure gauge, of such
a size and character that it is 5 times as sensitive as a water gauge;
and that the pressures due, represented in feet of air column, of a
density such as to cause it to weigh -078 lbs. per cubic foot—this being
the weight due to dry air at 51 ° under a pressure of 30*03637 inches of
mercury: —the total ventilating pressure being equal to 100 feet of such
air. Then will the following table exhibit the results of the necessary
observations, which must be taken at the points indicated by the
letters. In the 1st Split 8,000 feet per minute.
Points of Movement p ures
Specific
Observation, as of junction . ¦¦ Cubic feet
. . „
t,i v n -i in column „ . .
resistance
on Plan. line of oil » . . n of air in
f.,
and water ,.' 8.°V, circulation . , .__•__
----------------------- . ,, the weight _. ,
intervening-
1st 2nd mthe of water. Per mmute"
air-way.
Point. Pont gaUge-
Inches 800C Observed JL
mcnes. 5 x 12 quantities. E*
ABODE P
Downcast Shaft. 0*375 5 20,649
(7) 11,725
a b 0-15 2 8,000
(7) 31,250
b p 1-05 14 8,000
(6) 218,750
f Thiq is flip
p r 3-075 41 8,000
(6) 640,625 (pressure due
r g 1-5 20 8,000
(6) 312,500 < tance'offered
ff x 0-225 3 20,649
(8) 7,050 [K9regu" Upcast Shaft, "j
including- the pres- 1 15 20 649
(7\ 35 175
sure due to the final f ••'• 15 ^»t)4y
W 6d>l7°
velocity........... J _________
100
In the 2nd Split of 12,649 feet per minute.
Downcast shaft. 0*375 5 20,649
(7) 11,725
a y 2-25 30 12,649
(6) 187,500
y m 1-875 25 12,649
(6) 156,250
m g- 1-65 22 12,649
(6) 137,500
g x -225 3 20,649
(8) 7,050
Upcast Shaft, ^
including-the pres- I g Q
sure due to the final [ '
K ' *
velocity........... J
______________ Too _______I______________
It will be seen from the tables that we have supposed 8,000 feet of
189
air per minute, to have circulated in the 1st Split, and 12,649 cubic
feet per minute, in the 2nd Split, at the times of observation, before
the " change."
In order that the table given may be understood, as well as many of the
calculations which are to follow, it is necessary to explain that,
having for perspicuity adopted 1 cubic foot of air per minute, as the
unit whereby to determine what is here denominated the " specific
resistance of an air way," the result is, that these resistances are so
very minute that they would generally require the prefixing of a great
number of cyphers before the digits, to express them in decimal notation
; and to avoid this inconvenience, the numbers enclosed in parentheses
indicate the number of cyphers which actually require to be, (yet which
are not) prefixed to the digital parts of the numbers, in order
correctly to express them.
In future calculations, it would be better to adopt a thousand cubic
feet per minute as the standard, whereby to determine specific
resistances, so as to reduce the number of cyphers required; in such
case, bearing in mind that the results would not come out in cubic feet,
but in cubes of air, 10 feet square on each side; that is to say, in
thousands of cubic feet.
Inthenotationjustmentionedthenumber(7)ll,725 =-000,000,011,725, and the
number (6) 218,750 = -000,000,218,750, &c.
By the use of such a gauge as we have supposed in this example mine,
the errors of observation would not in any case amount to more than
i^o-th part of the total ventilating pressure employed, even if we
suppose
that the error was as great as ^th of an inch on the scale of the
instru-
12 x 5 x 100 ment; because -------—-------= ?| inches of scale on the
gauge would
be required to indicate the total pressure of 100 feet of air column;
soi)* part of the density of water; the instrument being 5 times as
sensitive as a water pressure gauge; and 7| x 20 = 150—20th parts of an
inch.
On referring to the diagram, it will be seen that we have not got, in
our tabulated observations, the specific resistances of the following
parts of the air-ways; owing to their being dumb before the change. In
No. 1 split, from p through q to x. From b to m, uniting No. 1 with Nos.
2 and 3 splits. From a to v in No. 4 split. As they will form a part of
the routes traversed by the air after the change, it will be necessary
to know beforehand, what their specific resist-Vol. III., Dec, 1854,
c c
190
ances really are; and this can only be ascertained by taking their
dimensions, and calculating- them by the rules given in an earlier page
; and even to do this will require a knowledge of the coefficient of
resistance, due to the nature of the materials composing the interior
surfaces of such air-ways, and which it may, therefore, be worth while
ascertaining, by a series of experiments on passages exposing different
kinds of mineral substances to moving air, the general rules given in
Chapter 5 of this memoir will enable us to determine these coefficients.
After calculating the amounts of the specific resistances of the parts
just alluded to, they will have to be added to those of the remainder of
the particular routes, of which they are intended to form a part, after
the change of air.
From p to v, which is to become dumb or unventilated after the change of
air, will also require that its specific resistance be found, either by
the use of the gauge, or by measurement and calculation, and deducted
from No. 4 split's specific resistance as found from observations at b
and r, &c. Let us suppose that we have so determined these resistances,
and found them to be as follows:—
From p through q to x .. = (9) 6.
From b to m .. .. .. = (9) 2.
From a through w to v .. = (9) 2.
From p to v .. .. .. s (9)1.
Let it further be presumed that we -^
have calculated, by the formula given,
or actually observed by the gauge,
that the loss of pressure at the regu- \ ) '
lator r, is equal to a specific resistance of. See [1] and
[64].......^
Then, after the change of air is effected, it follows that the specific
resistances offered to the several splits of air, will be, as in the
following-tabular statement; on the presumption that each current is
pursued from its entering the mouth of the downcast shaft, till it is
discharged at that of the upcast shaft.
191 TABLE,
Shewing- the specific resistances of each of the routes, taken by the
different splits of air in the example, after effecting* the change.
No> Reference to the route of the splits, g
ific reBistanceB#
as given on the Plan. r
0 Com- _. ,
. Of the entire
~ ... mence- Intermediate. Ending. e *\ V
route, being-the
fei)llt- ment.
separately. ^oft'he portions.
l"~ Top. Downcast Shaft. Bottom. (7) 11.725
a b (7) 31,250
b p (6) 218.750
p q x (9)
600
Bottom. Upcast Shaft. Top. (7) 35,175
(6) 297,500
2 Top. Downcast Shaft. Bottom. (7) 11,725
.a b (7) 31,250
b m (9) 200
m n g (6) 137,500
g- x (8) 7,050
Bottom. Upcast Shaft. Top. (7) 35,175
(6) 222,900
~3 Top! Downcast Shaft. Bottom. (7) 11,725
a b (7) 31,250
b m (9) 200
m 1, y g- (0) 156,250
g x (8) 7,050
Bottom. Upcast Shaft. Top. (7) 35,175
(6) 241,650
4 Top. Downcast Shaft. Bottom. (7) 11,725
a w v (9)
200
b (less p to v) r (6) 640,525
r (less reg-ulator) g- (9) 200
g- x (8)
7,050
I Bottom. Upcast Shaft. Top. (7) 35,175
(6) 694,875__
~~5 Top^ Downcast Shaft. Bottom. (7) 11,725
a e, h,i,k,y g- (6) 187,500
g x (8) 7,050
______Bottom. Upcast Shaft. Top, j (7) 35,175
(6) 241,450
An inspection of the diagram, shews that in order to apply the formulae,
to determine the gross resistances encountered by each of the new splits
of air, both where they are alone, and in the parts of their routes
where the resistance encountered is enhanced, by the union of other
currents with any one under particular consideration; we must treat the
4th and 5th splits or routes as acting in aid of each other from a to g,
so as to obtain the specific resistance of a single route, which would
be equal to their joint effects in transmitting air; and then proceed,
in a similar manner, to find the specific resistance of a single route,
which would transmit, under equal pressures, the same quantity of air,
as the joint quantities transmitted by Nos. 2 and 3 routes, from m to g
*, and afterwards determine the case for one split of air, dividing
itself into two parts, one of which pursues one route and the other a
different one, so
192
that one of them unites with a distinct split or current, and, in
conjunction with it, passes some distance; where they are met by, and
united to, the remaining part of the first mentioned current; and pass
on to the top of the upcast shaft with it; all of which will be more
readily perceived by considering; the following- processes of
calculation, perhaps, than by any direct consideration of the diagram
alone. We perceive hy [69] that
Mj + 2 x/Mx M2 + M2
where M is the specific resistance due to a passage giving the same
facilities for the transmission of air as the united actions of Mx and
M2.
If by m(45) we represent the resistance of a passage, equivalent to the
united actions of routes 4 and 5, from a to g; in transmitting air; and
if by m,! we represent the specific resistance of route 4 from a to g;
and by m5 that of route 5 between the same points; then by substitution,
in [69], we obtain,
m(45) = ------------------------;—g-------.-------------
m4 + 2 V m4 m5 + m5
Now the specific resistance m4 is (6) 640,925
Viz:— From a through w to v (9) 200
From v to r = p to r less p to v (6) 640,525 From r to g = (6) 312,500
Less, Regulator (6) 312,300 = (9) 200
Therefore m4 = (6) 640,925
The specific resistance of that part of split 5, from a to g-, passing
through e, h, i and k is m5 = (6) 187,500; and hence,
m(45)=________ (6) 640,925 x (6) IST^OO,___________
(6) 640,925 + 2 V(6) 640,925 x (6) 1875 + (6) 1875
The specific resistance of routes 4 and 5, so far as regards the parts
extending from a to g only, when acting in aid of each other in
transmitting air, is therefore (7) 78,971 as above.
Proceeding now in a similar manner to find the joint resistance of
routes 2 and 3, from m to g; that of 2 from m to g is (6) 137,500; and
that of No. 3 route between the same points is (6) 156,250 : the united
effects reduce the resistance to,
193
________________(6) 137,5 x (6) 156,25_________________
(6) 137,5 + 2 x J(6) 137,5 x (6)156,25"+ (6) 156,25 "~ (?) 36,6°7
These operations virtually reduce our directing diagram to the form of,
Referring to the above figure the resistances are:
From a to g via 4, 5, .............................= (7) 78,971
From a to b ....................................= (7) 31,250
From b tog, viz., b to m..............= (9) 200
and m to g via 2, 3,.. = (7) 36,607 = (7) 36,807 From b to x via c 1
p and q in No. 1 Route
is, from b to p............= (6) 218,750
and from p through q to x.. = (9) 600 =(6) 219,350 From g to
x.................................... =(8) 7,050
We now require to determine the proportions in which air would divide
itself over the series of routes offered to it, disposed as in the above
diagram, with respect to each other, and having the specific resistances
given above—where, it will be seen, a branch or split from one current,
after leaving its parent current at b, joins another current at g, and
in union with it traverses some distance, till at x they are joined by
the parent current itself, and thence proceed, in a united state, to the
shaft at z.
In such a case, when the entire quantity of air, or the sum of all the
currents is 1 cubic foot per minute, (the unit which has been adopted as
a standard for finding our specific resistances;) if we represent by c
the quantitv in the route which the branch current joins; and if we
represent the quantity of the branch current itself by b, then will (1 —
c) be the quantity in the parent current, before the branch current
separates from it; and (1 — c — b) will be the quantity in the parent
current after the branch current has left it; while the current of c
will be increased to (c + b) after being joined by the branch current.
And if m represent the specific resistance of an air-way, equivalent in
transmitting power to the joint action of all the air-ways j that is to
say,
194
if m = the pressure, in feet of air-column, capable of transmitting- one
cubic foot of air per minute, through the air-ways ; and if, in addition
thereto
The specific resistance in the part traversed by 1 — c is mx Do.
Do. c is ma
Do. Do. b is m3
Do. Do. (1 — c — b) is m4
Do. Do. (c + b) is m3
Then, since the currents will necessarily so divide themselves over the
three routes leading from a to x, that the loss of pressure, owing- to
the resistances encountered in each route, shall be exactly the same in
the two currents uniting at x; and also in those uniting at g; reckoning
the loss from the points where they respectively separated from each
other. And since the square of the quantity of air in each part,
multiplied into the specific resistance of that part, is equal to the
pressure expended on the resistances, we obtain the following series of
equations :
m = (1 - c)2 m: + b2 m3 + (c + b)3 m5..................[116]
m = c8 m2 + (c + b)2 m5 ............................... [117]
m = (i _ c)2 mx + (1 - c - b)2 m4 .....................[118]
The origin of which may be better seen, perhaps, by reference to the
following sketch, where the quantities and resistances are marked on the
routes to which they apply ; the compression of the air of the currents,
at the points where they separate or unite, necessarily being the same.
In the above equations m, = (7) 31,250, m8 = (7) 78,971, m8 = (7)
36,807, m4 = (6) 219,350, m5 = (6) 705, and it is required to find the
values of the quantities of air represented by c and b together with
that of m.
Deducting [117] from [116] we obtain
(1 — c)3 mx + b3 m3 — c2 m2 = o ..............[H9]
and by deducting [118] from [116] we obtain
195
b2 m3 + (c + b)2 m5 - (1 - c — b)2 m4 = o ......[120]
and from [119] there comes
b» = c3 mg — (1 — c)2 mi r
,
m3 ...................L " J
And since it would require the solution of a biquadratic equation, to
find the values of c and b from the above equations, it will perhaps be
best to ascertain their values by approximation, or trial and error,
according to the following Mule.
First, suppose or assume any value for c less than unity, because c is
but a part of the whole air, which has been taken at unity or one cubic
foot per minute ; and substitute the value so assumed for c, in [121],
and then, by that equation, proceed to find the corresponding imaginary
values of b2 and b; and substitute their values so found, in [120],
together with the assumed value of c j and then, if the assumed values
are correct, the positive and negative parts of the equation [120] will
be equal to each other, as is indicated by the terms of the equation; if
the positive terms exceed the negative terms in value, the error will be
the excess in question, and be called a + error; if, on the other hand,
the sum of the negative terms is greater than the sum of the positive
terms, the excess will be called a — error j when the error is a plus
error there must be assumed a new value of c, less than the first
assumed value; and if on the other hand the error is a minus one, we
must assume a new value of c, greater than the first assumed value ; and
proceed as with the first assumed value of c, by substituting it in
[121], and finding the corresponding values of b3 and b; also as before;
substitute these new values of c, b3 and b in [120], and again find the
error or difference between the positive and negative parts of the
resulting equation; marking the error + when the positive parts exceed
the negative ones; and marking it — when the negative parts exceed the
positive parts, in value.
Then multiply each assumed value of c, by the error arising from the use
of the other assumed value of c.
After having proceeded thus far, the mode of operating will depend upon
the kind of signs with which the errors are affected.
1st. If the errors be of the same affection, that is if they have like
signs, so as to be both +, or both —, then subtract the one product from
the other, and also the one error from the other, and divide the former
of these two remainders, by the latter; and the quotient will be an
approximation to the value of c.
2nd. If, however, the errors be unlike, in their signs, the one being
196
positive, and the other negative, then add the two products together,
and also add the two errors together; and divide the former sum by the
latter, and the quotient will he an approximate value of c. The first
approximation to the value of c, so found, may now he made use of, by
finding the error to which it gives rise, and using it, in conjunction
with a new assumed value of c, and its corresponding error, to
approximate nearer to the true value of c ; or two new values of c, one
a little greater, and the other a little less than the first approximate
value of c may be made use of in a precisely similar manner to the two
original assumed values of c, to arrive at a nearer approximation to its
true value; and these processes may be repeated until we have determined
the true value of c, to any required degree of nicety.
Now we have, in the example in hand, taken, in reference to the case
just investigated:
mx or a to b........................ = -000,000,031,250
m2 or a to g via 4,5,................ = -000,000,078,971
m3 or b to g via m in 2, 3, .......... = -000,000,036,807
m^ or b to x via c, 1, p, and q, in No. 1 = -000,000,219,350
m5 or g to x...................... = -000,000,007,050
which may be illustrated by the following diagram—
Let us, in proceeding to find the values of c and b, first assume c = -4
and consequently (1 — c) = -6, and by [121],
t , -16 x (7)78,971--36 x (7)31250 _
b _ (7) 36807 V0'°
and,
b = V -037629 = ;19398
and therefore, by [120],
197
•037629 x (7) 36807 + -5939S2 x (8) 705 - 406022 x (6) 219,35 =
- (7) 32,2877
which is the negative error arising from assuming -4 as the value of c.
Now let -437 be assumed as a new value of c, and then (1 — c) = -563;
and by [121],
h» _ "43?a x (7) 78,971 - -563* x (7) 31250 1/Lnpo ~
(7)35807 = U°~
and consequently
b = V '14062 = -37499 and by [120]
-14062 x (7) 36807 + -811999 x (8) 705--188012 x (6) 219,35= (8) 20705
which is the plus error corresponding to '437 as an assumed value of c ;
and by the Rule given
SUPPOSITIONS. ERRORS.
PRODUCTS.
•4 — (7) 32,287,7 = (7) 14,109,72
•437^ + (8) 2,070,5 = (9) 828,20
sums (7) 34,358,2 (7) 14,937,92 and
/^ r,A,-o^— = '43477, which is the first approximation (7) 34,358,20
; Li
towards the value of c.
To proceed, let this approximate value of c be adopted as a new assumed
value of c, giving c = -43477; and (1—c) = -56523; and ^ _ -43477s x
(7) 78971 - -565232x (7) 31250 _ .13430 (7) 36807 and consequently,
b = s/'^mM = -36647 and hence, by [120],
•13430 x (7) 36807 + -801243x(8) 705--198762x (6) 21935=(9)8036 so that
this new supposition of c being = '43477 gives a plus error of (9) 8036:
and if we further approximate to the true value of c, by this and the
preceding supposition; where the value of c was taken at -437, and the
result was a plus error of (8) 20705 ; we obtain, •437 ^ (8) 20705 = (9)
9001912 •43477 ^ (9) 8036 = (9) 3511732
Differences (8) 12669 = (9) 5490180 and
(9) 549,018 AOOn
(8) 1°6 690------"43335 which is the second approximate value
¥ol. TIL—Dec, 1854. D D
198
of c; and as this is very close upon the actual value of c (as may be
seen
by substituting- it in [116], [117] and [118]), we shall adopt it, and
hence,
c = -43335 ; (1 - c) = -56665; and, by [119],
b9= '43335a x (7) 78971 - -566658 x (7) 31250 = .ig03
(7) 36807
and,
b = ^"0303" = -36097 and consequently,
(c + b) = -79432• and (1 - c -b) = -20568
and by substitution in [116], [117], and [118],
m=-56652x(7)31250+-360972x(7)36807+794322x(8)705=(7)192782
m=-43335s x (7) 78971 + -794322 x (8) 705............=(7)192782
m=-566652 x (7) 31250 + '205682 x (6) 219350..........=(7)193134
the average of which values of m =(7)192899 The value of m,
(representing- the total pressure required to overcome the resistance
encountered by the air in the whole of the passages or routes leading*
from a to x, when one cubic foot per minute is the total quantity
transmitted by all the routes acting in aid of each other), it will be
seen, differs but little from the averag-e, in any of the equations,
each of which embrace a passage not included in the others; this slight
discrepancy arises from our not having- approximated more closely to the
actual value of c; we may, however, safely adopt and consider the
general "drag-" or-specific resistance, as being-
m==(7)1929 and by adding to this, the specific resistances of the
downcast shaft, furnace, furnace drift, and upcast shaft • which are
traversed by the entire body of air in the mine, and which together
amount to (7) 469, we obtain the entire drag- on specific resistance of
the mine = (7) 6619; which is, in fact, the feet of air-column required
to generate the necessary pressure, for transmitting- one cubic foot of
air per minute through such
a mine.
If we assume that after the change of air, the same amount of
ventilating pressure is employed, as was supposed to exist before the
change
was made, which was 100 feet of air-column; then, since Q = —• where
no constant forces of different amounts operate to affect the
ventilation through the air gravitating in ascending- or descending
parts of the routes, beyond what is embraced by P, and acts in common,
and equally
199
on each of the different routes, we have the total quantity of air
circulating* per minute, in the mine, after the chang-e,
Q = J (7)Zl9 = 38'86° Cubi° feet' The quantity circulating* before the
chang-e, under the same ventilating pressure of 100 feet of air-column,
was only 20,649 cubic feet per minute • shewing- that the change would,
if the same pressure were employed, cause an increase in the general
ventilation of more than 88 per cent., on the original quantity in
circulation, before it was effected.
In practice, however, it might be important to determine the quantities
which would circulate in each individual route after the chang*e should
be made; and this is done as follows, for the case in hand. The quantity
in each route will be proportional to the entire quantity circulating in
the mine, when the gravitation of the air in the ascending* and
descending-parts of the air-ways does not affect the results, and hence,
As l : Q :: (1 — c) : Q (1 — c), or
As 1 : 38,869 :: -56665 : 22,025 cubic feet from a tob-and As 1
: 38869 :: -43335 : 16,844 do. from a tog-•
from which it will be seen, that we have only to multiply the quantity
which is due to any route (when one cubic foot per minute is supposed to
be the total quantity of air divided amongst the whole of the routes or
splits), by the total quantity in circulation at any time, to obtain the
quantity due to that particular route j so that,
(1 — c) Q = -56665 x 38869 = 22,025 cubic feet from a to b
c Q = -43335 x 38869 = 16,844 do., from a to g in 4, 5.
38,869 do., total. And in like manner,
(1 _ c — b) Q = -20568 x 38,869 = 7,995 cubic feet, from b to x via 1.
(c + b) Q = -79432 x 38,869 = 30,874 do. from g to x.
38,869 do. total. And
b Q = -36097 x 38,869 = 14,030 cubic feet, from b to m and in 2, 3. But
the quantity 22,025 cubic feet per minute, passing from a to b, will be
distributed over Nos. 1, 2, and 3 routes • and since 7,995 has been
found as due to No. 1, the remainder 14,030, (found directly as above),
will be divided between routes, Nos. 2 and 3: and since the specific
resistance of No. 2, from m to g, is (6) 137500 • and that of No.
200
3 is (6) 15625; and of these routes acting jointly, (7) 36607; in each
instance from m to g; by [70]
140,30 J ^ / ' = 7,239 as the quantity in No. 2 route
and
11,030 s Ym 13757 = C'791 = the (luantity in No- 3 slAit?
their sum being-14,030 = the quantity passing from b to m as above.
And similarly, having found 16,844 cubic feet to be the quantity passing
from a to g via splits Nos. 4 and 5 } and the specific resistance of No.
4 route (6) 640,925, and of No. 5 (6) 1875, their united opera-tion
reducing it to (7) 78971; so that, by [70],
16,844 \ ^ ' = 5,913 = cubic feet per minute in No. 4 ^
' * split, from a to g
and
16,844 (^) ?8?971 = io 931 rs cubic feet per minute in No. 5 ;
*4 (6) 187,5 . - *
K ¦ split, irom a to g
Their sum being .. 16,844, as before found.
We have therefore determined the quantities in each of the splits to be
as follows s—¦
Cubic Feet per Minute.
In No. 1 split from b to x........................ = 7,995
In No. 2 split from m through n to g.............. = 7,239
In No. 3 split from m through 1, y, to g.......... = 6,791
In No. 4 split from a through w, v, d, e, f, r, to g .. = 5,913
In No. 5 split from a through e, h, i, k, y to g [...... = 10,931
Giving as the total quantity of air in the mine .... 38,869
cubic feet per minute, as already stated.
The sum of the quantities in Nos. 1, 2, and 3 routes, = 22,025 cubic
feet, traverses the passage from a to b. The sum of the quantities in
Nos. 2 and 3 routes passes from b to m, and is 14,030 cubic feet.
The sum of the splits Nos. 2, 3, 4, and 5 passes from g to x, and is
30,874 cubic feet per minute.
The total quantity of air in the mine, 38,869 cubic feet per minute,
passes down the downcast shaft at a, and also from x, through z, and
up the upcast shaft.
201
It can be shewn that the pressure required to overcome the resistances
encountered by each particular split of air, considered in its passage
from the top of the downcast shaft, to its reaching the top of the
upcast shaft will be of equal amount.
Since the conditions we have supposed, presume that the air is neither
accelerated nor retarded by the gravitation of the air in the workings
of the mine, and only the gross ventilating pressure operates in each
route ; it results that [67] the square of the quantity of air, in cubic
feet per minute, circulating in each route, or part of a route,
multiplied by the specific resistance of such route, or part of a route,
will give the total height of air column required to overcome the
resistances encountered, and to propel such air through such route, or
part of a route j and therefore, the sum of all the resistances, so
found, for any particular quantity of air (from its entering the
downcast, up to its being expelled from the top of the upcast shaft,)
will be the total ventilating pressure employed; expressed in feet of
air column.
Taking first the air in No. 1 split j it, in common with that in all the
other splits, encounters the resistance of the downcast shaft, and also
that offered by the furnace, furnace drift and upcast shaft.
The specific resistances of the parts in question consist of,
That of the downcast shaft....................... (7) 11,725
From x through upcast shaft.................... (7) 35,175
Or, on the whole.............................. (7) 46,900"
and hence the pressure absorbed by these passages is 38;8692x (7) 46,900
= 70'856 feet of air-column.
The air in No. 1 route encounters, in common with that in Nos. 2 and 3
routes, a further resistance in passing from a to b, 22,025s x (7)
31,250 a 15*159 feet of air-column ; the specific resistance of this
portion of the air-ways being (7) 31,250, and the sum of the quantities
of air in these routes being 22,025 cubic feet per minute.
The air in No. 1 route encounters alone, from b, through c, to p, a
specific resistance of (6) 218,750; and a further specific resistance of
(9) 600 in passing from p, through q, to x; or of (6) 219,350, on the
whole; the quantity of air in the split being 7,995 cubic feet per
minute; and hence these portions of air-way require, 7,9952 x (6)
219,350 = 14'021 feet of air-column to propel the air through them.
202
The entire pressure in feet of air-column, due to the circulation of the
air in No. 1 route, will, therefore, consist of the pressures due to,
Shafts, furnace, and furnace drift................ = 70*856
From a to b................................. = 15-159
From b through c, p and q to x................. = 14-021
Or on the whole the pressure is.................. 100-036
feet of air-column; which, but for errors due to fractions, would have
been exactly 100 feet. In Nos. 2 and 3 routes or splits, the air,
besides encountering the resistances in the shafts, furnace, and furnace
drifts, together with that of the air-way extending from a to b, also
meets with the resistance of the air-way from b to m, whereof the
specific resistance is (9) 200; the pressure expended, 14,0303x (9) 200
= .039 feet of air-column.
The air in No. 2 route also encounters alone, the resistance arising in
the passage from m through n, to g; the specific resistance being (6)
137,500, and the air 7,239 cubic feet per minute; requiring a pressure
of 7,2392x(6) 137,500 = 7-205 feet of air column.
The specific resistance of the air-way from g to x is (8) 7,050, and is
traversed by the air in Nos. 2, 3, 4 and 5 routes or splits, amounting
to 30,874 cubic feet per minute : the pressure expended on the
resistance is therefore, 30,8743 x (8) 7,050 - 6-720 feet of air column.
On the whole, the resistance due to No. 2 split requires a pressure
composed of,
Shafts, furnace, and furnace drift.............. = 70*856
From a to b as in No. 1 split .................. = 15-159
From b to m................................ = 0-039
From m through n to g...................... = 7-205
From g to x................................ = 6*720
Or, on the whole the pressure is.......... 99*979 feet
of air column; which, but for fractions, should have been 100 feet; from
which, it will be perceived, it differs in a very slight degree.
The air-way extending from m through 1 to g, has a specific resistance
of (6) 156,250, and is traversed by the air of No. 3 split alone, and
therefore absorbs a pressure of, 6,7912 x (6) 156,250 = 7*206 feet of
air
column.
The entire resistance encountered by the air in No. 3 split, therefore,
arises as follows:—
203
Shafts, furnace, and furnace drift .............. = 70*850
From a to b................................ == 15*159
From b torn .............................. = 0-039
From m through 1 to g...................... = 7*206
Fromgtox................................ = 6*720
Amounting in all to.................. 99-980 feet
of air-column.
The specific resistance of the air-way extending from a through w, r, d,
and f, to g, is (6) 640,925, where it is traversed only by the air in
No. 4 split j the entire pressure required to overcome the whole of the
resistances encountered by such air, consists of that due to the above
or
5,9132x (6) 640,925 ............................ = 22*409
Shafts, furnace, and furnace drift................ = 70*856
Fromgtox.................................. = 6-720
Giving as the entire pressure expended...... 99*985
feet of air column; again approaching very closely to the ventilating
pressure of 100 feet.
In No. 5 split, we have the specific resistance of the air-way extending
from a through e, h, i and k to g, equal to (6) 187,500 j where there is
10,931 cubic feet of air per minute, or the mere quantity due to No. 5
split; requiring therefore a pressure of 10,9312 x (6) 187,500 = 22*404
feet of air column. The entire pressure due to this air consisting
of,
Shafts, furnace, and furnace drift................ = 70*856
From a through e, h, i and k to g................ = 22*404
From g to x ................................ = 6*720
Amounting on the whole to .............. 99*980
feet of air-column; a very near approximation to the entire ventilating
pressure of 100 feet.
Collected, therefore, we have the pressures due to each of the splits,
as below; where the errors arising from the fractions, and from the
difference between the true quantity, and the approximation to the
quantity of air passing out of No. 1 split, through Nos. 2 and 3 routes,
are exhibited—
Pressures in feet Errors in the
of air column. calculations.
No. 1 split................ 100*036 .............. + *036
No. 2 do................. 99*979 ......"......., - -021
No. 3 do................. 99-980 .............. - -020
No. 4 do................. 99-985 .............. - -015
No. 5 do................. 99*980 .............. - *020
204
So that the calculated pressures, in no case, differ from the assumed
ventilating pressure of 100 feet of air column hy more than 1-2,777th
part; affording sufficient evidence of the general correctness of the
calculations. It may he seen, that when only 20,649 cubic feet of air
per minute were circulating, before the change of air was supposed to be
effected, in the foregoing example, there was required a pressure of 80
feet of air column, to drive this quantity of air through the workings
of the mine; leaving only 20 feet of air-column to overcome the
resistances of the shafts and undivided air-ways at the furnace and
furnace drift; the effect of the change of air being to reduce the
expenditure of pressure on the workings, to 29*144 feet of air column,
even on the increased quantity of air; thus leaving, out of an equal
gross ventilating pressure, 70-856 feet of air-column to overcome the
resistances encountered hy the air in the shafts, furnace and furnace
drift; and hence the great increase in the quantity of air put into
circulation in a given time, after making the change of air.
The preceding results plainly indicate the great benefit arising to
ventilation from reducing, virtually, the specific resistances of the
air-ways of a mine, by ventilating them, as far as may be safely
practicable, with a number of distinct splits of air.
If the ventilating pressure were independent of the area of the shafts
and undivided air-ways near them, they should be made of the greatest
practicable area, to ensure the best results in ventilation. This is the
case with reference to a downcast shaft and all level air-ways, whatever
may be the power employed • but when furnace ventilation happens to be
the power made use of, there will probably exist a limit to the area of
the furnace drift and upcast shaft, to exceed which would operate
prejudicially on the ventilation of the mine, all other things being the
same; inasmuch as the cooling of the air, in the air-ways and shafts,
traversed by it after passing over the furnace, will become greater, and
greater, as we enlarge their area, and thereby reduce the ventilating
pressure.
At the same time any enlargement of these air-ways must be attended with
a reduction of their specific resistance, which would be to set against
the increased loss by cooling; these, in fact, are leading elements for
consideration in determining what is the best possible area of section
to be given to upcast shafts, in order to realize the maximum
ventilation by the consumption of a given quantity of fuel, when the
power employed is that of furnaces. The specific resistance offered by
the downcast shaft and workings would, however, also require
consideration in
205
determining this much disputed question • and since the amount of the
specific resistances of the air-ways would not remain constant, in the
same mine, for any great length of time, the upcast shaft could not
remain of the best possible area for any longer period; yet it is
possible that it might be so little effected by changes in these
resistances as practically, if not scrupulously, to do so; and therefore
the matter appears to be one well worthy of a strict investigation.
A general examination of the example given in the preceding part of this
chapter will show that in order to be able to determine, a priori, the
exact quantity of air which will circulate in each split under any given
or assumed ventilating pressure, it is necessary to ascertain the
specific resistances of each separate part of the shafts and air-ways,
which are to be traversed by quantities of air of different amounts, and
then to put the results into the form of equations, on the principle of
the barometrical pressure of the air at all the points of separation and
reunion of the splits of air being of equal amount, for each of the
splits so separating, or uniting; while the total expenditure of
pressure per unit of surface, must be equal to the entire general
ventilating pressure employed, except in so far as the effects of the
gravitation of the air in any of the ascents or descents traversed by
the air, having different temperatures and densities, may operate to
render the pressures required in some of the splits, greater or less
than in others; in cases where these causes of discrepancy exist it will
become necessary to introduce constants into the equations, representing
the pressures generated, or absorbed, in each route or split of air; and
then to determine by them, the quantities of air due to each split, when
some definite pressure is employed to produce ventilation; as in such
cases, the proportions in which the air will divide itself over the
different splits will vary with the amount of general ventilating
pressure employed, and consequently with the total quantity of air put
into circulation in a given time.
As this communication has already extended itself to perhaps too great
an extent, it is not considered worth while giving any particular
example to illustrate a case of the above character.
Vol. III.—Dec, 1854. B e
APPENDIX.
I.—Note on certain Formula for finding the Telocity of Air in
Pipes, fyc.
When the form and dimensions of the section of any pipe, flue, or
airway, happen to be uniform throughout the extent of the passage, a
constant may be found, of such value, that if the velocity which would
have prevailed in the absence of resistances be multiplied by it, the
quotient will be the actual velocity. Adopting the following notation—
h == height in feet of head of air column, equal to the pressure
employed; Y = velocity in feet per minute, due to the head h, if there
were
no resistances; v = actual or observed velocity in feet per minute; L =
length in feet of pipe, flue, or air-way; c = perimeter of section of
air-way, in feet; Q as cubic feet of air per minute; A == area of
section of air-way, in superficial feet; m = constant multiplier for any
given air-way, being the ratio of
v to V, so that m = — j
D = diameter of pipe, flue, or air-way, in feet, when the section is
circular; or the side of the section of the same when it is square;
?r = 3-1416, the ratio of the circumference to the diameter of a circle.
Then, by [54] and [63],
, kLcQ3 Q2
h ss------3L j, ----2------................. ra]
A8 231600 Aa ' J
208
and hence,
h==QMkLc 1 1 ................ ,b]
Aa I A ^ 231600) l J
and also,
Q hA
v= ~= ------------------..............[e]
kLc +---------
^ 231600
In the absence of resistances, by [10], the velocity due to the head of
air column, h, would have been
V = n/ 231600~h......................[d]
but by our notation
in = —.......................... I e i
V
and by substituting in [e], the value of v in [c], and that of V in [d],
we
obtain,
iiA
kLc+---------
m= -______*M600_.................[fj
N 231600 h which is reducible to
m = 1 A ..............fe]
N 231600 k c L + A
and since v = Vm; and also V = ^/231600 h
_____ A
v = V231600h x T^T^n i t ^ a ..........^
231600 k c L + A N
which is the general equation for the velocity v.
When the form of section is a circle D2-^- = A; and D * = c; which
values of A and c being substituted in [g], gives
T?—
m~ 231600k D*L + D** 231600x4kL + D
4 4 a,
which may be expressed thus,
209
1 P :....[ij
jn zs: -----------------¦__i-------- X
""--------------------t
231600 x 4 k L +_____-______D
^ ** 231600 x 4k
when the form of section happens to be a square D2 = A, and also 4 D =
o; and by substituting these values of A and c, in [g], we obtain
d3 __ n_ d
m~ 4 231600 x 4kDL + Da ~ J 231600 x 4kL+ D which may be expressed thus,
m== ____I_____x ---------—.------- ••••M
231600 x 4 k L +-----------------D
** n ^231600 x 4k
by which we see that the multiplier, m, has the same value in [i], as in
[k] j that is, it is the same, whether the section be circular or
square; in either case the actual velocity is
D
v = 231600 h x-----------------x --------------t--------------M
231600 x 4k L . 1 p
4 4 4 231600 x 4 k
By calculating the values of---------------- and also the square roots
J B 231600 x 4 k,
H
of the same, for the various values of k; given in Table 1, we have
t« * • i a*-* Corresponding-
Corresponding
Nature of Material State vak£s
rf 8 values of
composing interior surface ° Values of k. j
j
of air-way. Air. 231,600 X 4
X k 4 231,600 X 4 X k
Clean Bricks or Pottery----- Hot. -000,000,268,810 4-0157
2-0039
Old Tarred Cast Iron...... Cool. -000,000,019,050 56-664
7"5275
Old Rusty Sheet Iron...... Cool. -000,000,027,517 39-228
6-2633
Tinned Iron.............. Cool. -000,000,025,400 42-498
6-519
Cast Iron, covered with soot Hot. -000,000,052,917 20-399
45165
Clean New Sheet Iron...... Hot. -000,000,105,830 10-2
3-1937
210
By substituting, successively, the tabulated values
of--------------------
J fa J
231600 x 4 x k
| 1 .
and J QQifiQo y 4 x k *n M> we °^am ^ne following- formulae for the
passage of air through pipes, flues, or air-ways, having an uniform and
equal, square or circular section ; when D is the side of the square, or
the diameter of the circle, as the case may be; and v the velocity in
feet per minute.
According to Peclet, -when the material is Burnt Earth, (brick)
^
or Pottery,—new, clean, andv= 231,600 h X 2-0039 ------———
.... [m]
free from soot; the air being aJ
-nJL + 4'0157D
heated.
According- to Girard, when the ..... _______
--------------------
material is Cast Iron,—after __ 0„, cnn •. .. ^.kotk
^ r^n
, , , , '.. . , v = 231,600 h X
7*5275------------------.... Tn
long-use, and tarred or pitched; . '
-\L + 56-664D
the air being cool.
According to Girard, when the r~-------------
Jj ~
material is Rusty Sheet Iron ; v = 231,600 h X
6-2633-------------------------[o]
and the air cool. N
N L + 39-228 D
According to Daubuisson, when ----------------
^
the material is Tinned Sheetv = 231,600 h X 6-519 --------=——
.... [p]
Iron; and the air cool. N
NL + 42-498D
According to Peclet, when the
material is Cast Iron,—after ¦—
^
long use as a chimney, andv= 231,600 h X 4-5165
------------------ .... [q]
covered with soot; the air being N
N L +20399 D
heated.
According to Peclet, when the
___________--------------------
material is New Sheet Iron,— OQ, cnrv, v. „ ,„<,-,
D r ..
r c „ ¦, , ' .T= 231,600 h X
3'1937 ------------------ .... [r]
tree from rust and soot; and '
j. jq^ jj
the air heated. ^
The first of the preceding series of formulae, [mj, which answers to the
passage of heated air through an air-way, exposing to the moving air a
surface of burnt earth (brick) or pottery, new, clean, and free from
soot, may be considered as being identical with that which Mr. G. C.
Greenwell ascribes to Mons. Peclet, and which he found to agree very
closely with an experiment made by himself, to ascertain the resistance
encountered by air passing down the downcast shaft, through a gallery
forming a part of the underground workings of the Crook Bank Colliery,
211
and, after being heated by passing over a ventilating furnace, up the
upcast shaft.
The formula in question would, in the notation here employed, stand thus
v = V" 231,600 h x 2-06 —-5-----........ r«1
the constants in which differ slightly from those given in the preceding
formula [m], the cause of which I have not ascertained.
It may, however, be proper to state, that although I do not perceive any
formulae of the form of the above, in M. Peclet's "Traite de la
Chaleur," third edition, 1844; the only work by M. Peclet in my
possession; yet I observe that Mons. M. P. Berthier in his "Traite des
Essais par la voie s£che," exhibits a formula agreeing with [s], which
he ascribes to M. Peclet.
The formulae given in this memoir, in relation to the subject hereunder
consideration, have been constructed from the general laws ascertained
to prevail, in experiments made by different persons, as recited in
Chapter I; the constants depending on the value of the coefficients of
resistance k, being deduced from those given by Mons. Peclet in the work
already alluded to; where the coefficients are 47,245 times greater than
are suited to the formulae here given, so that this has been
accomplished by dividing the constants given by M. Peclet, by that
number; which arises from the continued multiplication of the number of
English feet in a French metre, 4, and the square of the number of
seconds contained in a minute, (3,600), into each other; thus,
3-2809 x 4 x 602 = 47,244-96.
II.—Note on the Coefficient of Resistance due to Steam in Pipes.
It may be interesting to know, that from an experiment made by Mons.
JRudler, M. Peclet deduces two limits of the value of the coefficient of
resistance encountered by steam in passing through a pipe, one
bein°-•0032, and arises on the presumption of the escaping steam
expanding to the volume due to the pressure of the atmosphere; and the
other -004, which arises out of the experiment, on the supposition of
the steam having* escaped at the pressure and volume due to the steam in
the boiler, which was loaded above the atmospheric pressure to the
extent of 0-m2 of mercury.
212
These quantities would give the pressure of the steam, over that of the
atmosphere, as 39-3708 x 0,m2 = 7'8741 English inches of mercury; and
the coefficient of resistance k (as suited to the formulae in this
memoir) as being
k " ^47245" = •°00.°00,067,73 if the steam escaped with the volume due
to the pressure in the boiler, without undergoing expansion; but if, on
the contrary, the ste,am be supposed to have escaped in an expanded
state, at the pressure due to the atmosphere, then, from this experiment
•004 k = "17~M5" = -000,000,084,66
and hence the actual value of k, in this experiment, may be considered
as lying between these limiting values.
M. Peclet does not state what was the nature of the material composing
the escape-pipe trsed in M. Rudler's experiment, as he concludes, I fear
on too slight grounds for reliance, that the resistance encountered by
steam flowing through pipes, will not vary, as in the case of air, with
the nature and state of the interior surface of the pipe ; presuming
that the steam will move against a thin film of water, adhering to the
inner surface of the pipe, arising from the condensation of the flowing
steam, and consequently rendering the coefficient of resistance
independent of the nature and state of the material composing the
conducting pipe.
It appears rather surprising, that more numerous and decisive
experiments have not been made, to determine the coefficient of
resistance due to steam moving through pipes; seeing that it bears so
closely on the proper working of steam engines.
III.—Note on a Formula relative to the Flow of Gas through Pipes, by Mr.
Hamhsley, of Liverpool. Our worthy President, in laying before the
members of this Institute, the result of his numerous and valuable
experimental inquiries into the relative value of the Furnace and Steam
Jet in the ventilation of Coal Mines, notices a formula for finding the
velocity of gas, flowing through gas-pipes, which Mr. Hawksley, of
Liverpool, is said to have deduced from experiments on gas conveyed in
pipes many miles in extent.
213
The formula in question is
v = 96 ^±3?J_I)S...................... ft]
J lm + 360s L
Where
v = velocity of gas in feet per second.
T = average temperature of upcast shaft.
D = depth of upcast shaft in feet.
t = temperature of downcast shaft.
s = sectional area of air-courses in feet.
m = perimeter of section of air-courses in feet.
1 = length of air-courses in feet.
Now, in the above, ( -~-----tj^- )D is evidently the pressure, per unit
of surface, employed; expressed in height of gas-column, in feet; and
is, therefore, equivalent to our symbol h, as used in this Appendix.
Again, s in the above, is identical with our symbol A; m is the same as
our c; 1 in Mr. Hawksley's formula, agrees with our L; and v in Mr.
Hawksley's formula, since it relates to the velocity in feet per second,
is only one-sixtieth part of the value of the same letter in this
Appendix, which expresses the velocity in feet per minute.
By replacing Mr. Hawksley's symbols with those we have already used, his
formula becomes
v = 96 ^----** tr»A a x 60
n L c + 360 A
or
v = 5760 —---------¦.,- .¦
N L c -J- 360 A
In order to make this latter equation correspond with our equation [c],
it is only necessary to multiply that part of the right hand member
which is
not embraced by the radical sign, by \/ k; and, (thus preserving the
value of the expression) to divide the remaining part of the expression
by the same, or by s/ k, giving
v = 5760 xTFJ-p^----** t,n , . --------------......[u]
N k L c + 360 k A
and since, by [c],
Vol. III., Dec, 1854, * p
214
4 + 231600
we ought to have,
5760 V~k = 1
and hence,
k = ^=*000'000'°30?U ......................W
If, in Mr. Hawksley's experiments, the gas escaped without suffering any
contraction of the flowing vein, and if there were no other resistances
to overcome than that of friction, as due to the pipes, we ought also to
have had,
360 k == 231,600 and hence, in that case
k=360x231,60ir=-000'000'0n'994........W
This discrepancy between the two values of the coefficient of
resistance, as deduced from Mr. Hawksley's formula, admits, in all
probability, of being explained in one of two ways; both indicating that
the actual value of k, as suited to our formulae, and derived from Mr.
Hawksley's observations, is neaily expressed by -000,000,030,14.
In the first place, if we suppose that no pressure was expended,
excepting that due to the velocity v, and the frictional resistance, yet
if the pipes exposed an extensive rubbing surface in proportion to the
area of their section, in other words, if 1 c was very great in
proportion to A, then the formula given by Mr. Hawksley would not
sensibly differ from observation, because the denominator of the
fraction under the radical sign would not be materially increased by
multiplying the small quantity A, denoting the area of the pipe, by 360,
instead of multiplying it by a smaller, and more correct multiplier.
The multiplier according to the investigations contained in the
preceding part of this memoir, on taking the value of k at
'000,000,030,14,
would be
________________________ __ iiq-oa
231,600 x -000,000,030,14
instead of 360; presuming there to have been no expenditure of pressure
215
beyond that due to the velocity in the pipe, and the corresponding
frictional resistances.
If, on the other hand, Mr. Hawksley's formula were applied to pipes of
short length, and presenting little rubbing surface in proportion to
their diameter, so far as we can rely upon the results obtained by
Peclet, Girard, and Daubuisson, it would indicate less than the real
velocities; unless, indeed, there happened to be an expenditure of
pressure at a contraction of the flowing vein, for which no allowance
were made in the calculation j a circumstance, perhaps not unlikely to
have occurred, and which might have the effect of accounting for Mr.
Hawksley having adopted the large coefficient of 360, instead of 143, as
theory, and the experiments of other persons, would indicate to be
required, on the presumption that -000,000,030,14 is the value of k, as
suited to ordinary gas
pipes.
These remarks may be illustrated in the following manner; suppose we
apply the formula [uj, corresponding in value with that of Mr. Hawksley,
to determine the velocity due to gas flowing under a pressure of 130
feet of gas-column, through a pipe 500 yards, or 1500 feet in length,
and 6 inches, or '5 of a foot in diameter j presuming the coefficient of
resistance k to be -000,000,030,14: we obtain,
v = 5760 X */"^000,000,030,14
~~ 130 x -52X "7854
X^ -000,000,030,14 X 1500 X "5 X 3-1416 + 360 X '000,000,030,14 X -5a X
"7854
= 59072 feet per minute.
In the above example, if we had used the number 143*26, instead of Mr.
Hawksley's constant, 360, we should have obtained the velocity as 595'97
feet per minute, which only exceeds that given by Mr. Hawksley's
formula, by about 1 per cent, of its amount.
As previously stated this discrepancy would be greater, as the length of
pipe is lessened, and its diameter increased j but the existence of a
vena contracta, either at the entrance, or exit ends of short pipes
experimented upon, if no direct allowance were made for their effects,
would be likely to lead Mr. Hawksley to conclude that 360 ought to be
the constant used in all cases; if indeed it was determined in an
empirical manner from experiments.
If we consider, therefore, that -000,000,030,14 is the value of the
coefficient of resistance encountered by gas or air flowing through
ordinary gas pipes, (of cast iron ?) we see that it is about 10 per
cent, greater than
216
the same coefficient, in the case of rusty sheet iron pipes, as
determined by M. Girard; and even 50 per cent, greater than in the case
of cast iron pipes, coated internally with tar or pitch; a fact which
almost induces one to suppose that the ventilation of mines, may
hereafter come to be improved by coating- the principal air-ways, but
more particularly the shafts, with some substance, offering less
resistance of a frictional nature, than the ordinary bare walls
generally present to the passage of the air.
———_
j
IV.—Note on the Discharge of Water through Pipes having a Circular
Section.
The formula given by Eytelwein for finding the velocity with which water
flows through a pipe is,
V = 26'44 t -Tr"^-....................W
L +54 D
where
v = the velocity in French metres, per second.
P = the height of head of water-pressure, in metres.
D = the diameter of the pipe, in metres.
L = the length of the pipe, in metres.
The above formula, on being so modified as to express by v, the velocity
in feet per minute; by h, the height of head of water, in feet; by D,
the diameter of the pipe, in feet ; and by L, the length of the pipe, in
feet; becomes,
v = 2873-5 T h ?. -.......................[y]
N L + 54 D UJ>
and may also be written or expressed thus
t= V 231600b x 2873<5 + r~IS—............... W
V 231600 * L + 54 D
and since , . — = 5-9709, V 231600 ;
from what has been stated in a previous part of this Appendix, it may be
seen that in this instance,
4 231600 x 4 k ~ 5'97°9' and conse(lliently
k = 231600 x\x 35-652 = -000,000,030,27a
217
which is the value of the coefficient of resistance in the case of
water, as suited to any of the formulae contained in this memoir; a
coefficient, found by experience, to be constant for water, whatever may
be the nature or state of the internal surface of the pipe or passage,
in which it flows.
According, however, to the formulae given by the authorities previously
alluded to, we ought also, in this case, to have had
S3160Qx4x54=k=-000'000'019'989
which is only about two-thirds of the value of the same coefficient, as
found from the preceding and more important part of the formula. t The
more correct value -000,000,030,278, of k, will, from the nature of the
formula, be found to give results closely agreeing with practice, in any
of the formulas which are given in this memoir : the number 54,
occurring in the denominator of the fraction under the </
, being
probably too high, arising from the same causes as have been suggested
for a similar occurrence, in the case of Mr. Hawksley's formula, for the
passage of gas through ordinary gas pipes: indeed, it seems a little
remarkable that Mr. Hawksley's constant, for gas in pipes, agrees so
closely with the above, as due to water, according to the formula of
Eytelwein ; the former being -000,000,030,14, and the latter
-000,000,030,278, while each of them give the multiplier, before alluded
to, considerably greater than reasoning would indicate, and than has
been found by other persons to agree with practice and experiments.
V.—Note on the prevailing Ideas of Gas .Engineers on the Discharge of
Gas through Pipes.
In the " Mechanics' Magazine" No. 1368, of Saturday, October 27, 1849; a
letter appears, of which the following is a copy:—
FLOW OP GAS THROUGH PIPES.
Sir,—In no department of gas engineering- is there more need of
experimental information than in that of the flow of gas through pipes,
inasmuch as the results given us by rule do not ag-ree with those found
in practice.
I believe that the same inconsistency holds in regard to the flow of
water and other fluids; but my experience being- confined to gas, I will
limit my observations to that branch of the subject.
I have read the best works upon the subject, and had the private
opinions of the most eminent engineers, and, with one exception, I have
been told that for the difference
218
of length, the discharge will he inversely as the square roots of the
lengths, and that,, for different diameters, the discharge -will he
directly as the squares of the diameters.
To take an instance :—A pipe, 6 inches in diameter and 500 yards long,
is found to-deliver 3,686 cuhic feet; whereas the same pipe, if extended
to 1000 yards in length, will only deliver 2,606 cuhic feet. This has
heen proved by experiment, and we will
assume it to be correct.
But we are told that a pipe, 12 inches in diameter and 500 yards long,
will deliver only 14,744 cuhic feet; or, if extended to 1000 yards in
length, its discharge will be reduced to 10,424 cubic feet. In both
cases it will be observed that the amount said to-be delivered by the
12-inch pipe is exactly four times that delivered by the 6-inch pipe,,
or as the square of the area {diameter 1) ; and here I disagree with
those who have-written before me.
In a calculation of this kind there are involved a great many
intricacies; but I will pass over those minor considerations, such as
the friction of the particles one against another, &c, which theory,
perhaps, more than practice, would lay stress on, and merely advert to
what appear to be the main causes requiring notice, namely, the
gravitating power or inertia of the gas and the surfaces against which
it has to rub during transmission, these having to be overcome by the
force or pressure employed.
Let us see then how this applies in the case before us. A pipe, 6 inches
in diameter, is, in circumference, 18"8496 inches; and four such pipes
equal in capacity to one 12-inch pipe, are in circumference 75-3984.
Now, a pipe 12 inches in diameter is, in circumference, 37*6992 inches,
or just one-half; so that in one case we have double the rubbing surface
which we have in the other. Under such circumstances, I pronounce it
physically impossible that the discharge can be the same.
I am aware that some modern writers have remarked that there will be a
slight advantage in favour of the larger pipe, from the cause I have
just mentioned ; but I contend that a passing notice of such an
important point is not enough, inasmuch as large pipes, from 12 to 16
and 18 inches in diameter, will deliver from 40 to 70 or 80 per cent,
more than the rule gives.
"We have found that when the 6-inch pipe was 500 yards in length, it
delivered 3,686 cubic feet, and when extended to 1000 yards in length,
its delivery was reduced to 2,606 cubic feet. Now, in thus extending the
pipe, what did we do 1 Why, increase the rubbing surface. "We thus have
a rule for calculating the effect of length friction, while side
friction is entirely overlooked, just as if there was any important
difference between the one and the other.
For the reasons above stated I have been led to add one additional rule,
viz., that the discharge will be inversely as the square root of the
rubbing surface. A 12-inch pipe, therefore, will deliver at 1000 yards
length 14,731 cubic feet, an addition of 41 per cent. The difference
appears more conspicuous in very large pipes ; thus an 18-inch pipe is
reckoned to deliver, at 1000 yards, 23,454 cubic feet, whereas, by my
calculation, it will deliver 40,677 cubic feet.
I am not able to say that I have proved this rule by experiments
expressly made for the purpose ; nevertheless, I am prepared to say that
it agrees with my experience of the action of large pipes better than
any other rule I can apply. I therefore throw it before your readers to
receive their scrutiny, and shall be happy to hear of any rule that will
answer existing objections better.
October 18, 1849.
Geo. Anderson.
219
The rule proposed by Mr. Anderson in the text of the preceding letter,
it may be observed, does not agree with the rule by which he has made
the calculations given in the letter, if even we admit, as we evidently
must, that he has used the expression, " or as the square of the area,"
when he really intended it to have been, " or as the square of the
diameter j" because the latter expression agrees with the context, while
the former is at variance with it.
If by Q we denote the quantity of gas discharged in the unit of time; by
D the diameter of the pipe, by c its circumference internally, and by L
its length, each in the case which is taken as a datum, having been
proved by experiment; and if we further denote by Q the quantity in any
other case, in which D is the diameter, C the perimeter of section, and
L the length of the pipe j then, according to the statement in the
letter, the ordinary and erroneous rule gives
^ ~ 17s l Q
But in a pipe, it is evident that the rubbing surface is represented by
the product of the length and the circumference of the section of the
pipe; and since Mr. Anderson professes to have been led to add to the
above erroneous rule, by way of rendering it correct, an additional
rule, viz., that the discharge will be inversely as the rubbing surface;
we should have for his new rule,
This rule, however, does not agree with the calculations given by Mr.
Anderson in his letter; he has in fact made his calculations upon the
more correct principle of the discharge being directly proportional to
the cube of the diameter, and inversely to the square root of the
rubbing surface; which gives a rule expressed thus,
Q=-§> |^-Q ..............*......W
a rule which would be correct, and in accordance with the formula? in
this memoir, were it not that it omits to take cognizance of the
pressure due to the generation of velocity j and whenever the pressure
expended on the creation of velocity is a small proportion of the entire
pressure employed, the rule will give results nearly agreeing with those
given by the formula? in this memoir.
220
In Mr. Anderson's datum case, where the discharge was 3,686 cubic feet
per hour, or 61*43 cubic feet per minute, the pipe was 6 inches or -5 of
a foot in diameter, and 500 yards or 1,500 feet long; and if we assume
the coefficient of resistance (as due to the formulae in this memoir) to
have been -000,000,030,14, as deduced from Mr. Hawksley's experiments,
we should have for the entire pressure employed, in feet of gas column;
expressing- it by P,
_ 61-432 /•000,000,030,U X 1,500 X -5 X 3-1416 .
1 \
P _ (-52 X -7854)» \ 52 X "7854
+ 231 ,"600/
or,
P = 35-828 feet.
Letting A = area of section of pipes in superficial feet.
Q =-: the discharge in cubic feet per minute.
vr = 3*1416 the ratio of the circumference to the diameter of a circle.
D = the diameter of the pipes in feet.
L = the length of the pipes in feet.
g = the velocity in feet per minute, acquired by a body falling one
minute under the force of gravity = 115,800. k = the coefficient of
resistance, or the height of gas column required to
overcome the friction on one superficial foot area of rubbing
surface, when the velocity is one foot per minute j in this instance
taken at -000,000,030,14. By the formulae used in this memoir
Q = I PA8. ....................\B\
kLc+^-2g
and since A = Da -£- ; and also c = D r, when the section of the pipes
is circular, we have,
Q= ------*-d ..........................W
J4kL + 2i
and by this formula,
Q = 61-43 whenD = -5 and L = 1,500 Q = 43-569 when D = -5 and L = 3,000
Q = 34-549 when D = 1 and L = 1,500 Q = 24573 whenD =1 and L = 3,000 Q =
675-17 when D = 1-5 and L = 3,000
221
the above values of Q being multiplied by 60 will give the discharges in
cubic feet per hour, as due to the formulae in this memoir; and this
process, combined with the use of the rule given in the formula [A],
enables us to construct the following table, shewing the near agreement
between the rule used by Mr. Anderson, and the results given by the
formula? in this memoir.
Diameter j ., Discharge by Discharge as
Discharge by
of gas . °. what Mr. Anderson calculated by Mr. the
formula? used
pipes in . r * F states to be the Anderson, by
in this memoir
feet. ' usual rule. formula [^1.
[Cj-
Cubic feet <$* hour. Cubic feet & hour. Cubic feet <$ hour.
•5 1,500 3,686 3,686
3,686
•5 3,000 2,606 2,606
2,614
1 1,500 14,744 20,848
20,730
1 3,000 10,424 14,731
14,744
1-5 3,000 23,454 40,677
40,510
Dr. TJre, in his u Dictionary of Arts, Manufactures and Mines,"
erroneously states that the discharge from the end of a pipe is directly
proportional to the square of its diameter, and inversely as the square
root of its length; whereas, when all other things are constant, and the
pressure expended on creating velocity is so small that it may be
neglected, the discharge is proportional to the square root of the fifth
power of the diameter of the pipe, or what is the same, to the diameter
of the pipe raised to the power of two and one half.
In pipes where our coefficient of resistance k = '000,000,030,14,
(unless the pipes are very short), we will obtain sensibly correct
results by using any of the following formulae,
0 = 134,916 -~^- x D*...............\D\
N
0=134,916 -~~ ....................[jg]
N
Vol. III.—Dec, 1854. g g
222
or in logarithms, Log-. Q = 5-1300647 + H-f+ (HJx 5) -%^„ [f]
This may be verified by applying them to the cases given in the last
Table, taking P = 35*828 feet, as was done in constructing the Table,
and as was necessary from the nature of the case, if we admit k to have
been •000,000,030,14.
ERRATA
IN
MB. J. J. ATKINSON'S PAPER ON " THE TH.EOKY OF VENTILATION."
78 page, 15 lines from top, for pipe read pipes.
84 „ 11 lines from bottom, ./or [4] read (4).
94 „ 10 lines from top, insert a comma after the word shaft.
97 „ 8 lines from bottom, for equitation read equation.
98 „ 12 lines from bottom,^?' time read mine.
99 „ insert the sign of equality = after T, in formula [34]. 101
„ 13 lines from bottom, for (T~t) read (T—t).
132 „ 19 lines from top, for one cubic feet read one cubic foot.
160 „ 5 lines from bottom, for downcast shaft read downcast
column.
171 „ 11 lines from bottom, for less read greater.
179 „ 1 line from bottom, for effect read affect.
214 ,, 12 lines from bottom, for 1 c read L c.
216 „ in formula [z]for + J L + 54 D read X J L + 54 D '
219 „ 21 lines from top, insert the words " square root of the"
immediately before the words "rubbing surface."
223 NORTH OF ENGLAND INSTITUTE
OP
MINING ENGINEERS.
MONTHLY MEETING, THURSDAY, FEBRUARY 8th, 1855, IN THE ROOMS OF THE
INSTITUTE, NEWCASTLE-UPON-TYNE.
EDWARD POTTER, Esq., in the Chair.
The Secretary having- read the minutes of Council the
following-gentlemen were elected Members:—
Dr. Richardson, Newcastle• James Hall, Stenton Iron Works, near Derby¦
John George Bell, Newcastle• Peter Higson, Manchester.
The Chairman begged to apologize for the absence of their worthy
President, who, according to a telegraphic message sent to the
Secretary, was prevented attending that day in consequence of the roads
being blocked up with snow. With respect to the principal subject for
consideration, viz., that of the establishment of the Mining Colleg-e,
he thoug-ht they would all agree in thinking that it was a very
important matter to bring- before the coal trade. Mr. Taylor, he knew,
had some observations drawn out on the matter, but that gentleman was
not inclined to submit them to the meeting without the sanction of the
President. Mi*. Taylor had a few minutes ago been called away on
business, and he could not say whether he would be back again. He,
howrever, begged to inform them that a meeting of the Coal Trade was
held on Tuesday last, at which the subject of the Mining College was
most favourably considered, and a report by the Committee of the Trade
was read. The meeting unanimously passed a resolution concurring- with
the report
Vol. III.—Feb., 1855.
224
of their Committee and also with the report of the Mining- Institute, as
to the desirability of establishing- a College for the advancement of
practical mining- and manufacturing- science in Newcastle. As these
documents were in the hands of the Secretary he would call upon him to
read them to the meeting.
The Secretary then read the following- repoit and resolution:—
EXTRACT FROM REPORT OF GENERAL MEETING OF THE COAL TRADE.
Newcastle-on-Tyne, Coal Trade Office, Neville Hall, February 6th, 1855.
Your Committee now turn, not without gratification, to another topic
which is unquestionably indicative of the advancing1 state of the
trade—this is the Report of the Council of the North of England
Institute of Mining Engineers on the proposed establishment of a
Colleg'e of Practical Mining- Science, at Newcastle-upon-Tyne, laid
before this Committee by that body, and now in the hands of the Members
of the Trade generally. Presuming- that the details of this Report
are known to all present, the Committee can only proceed to impress upon
the Lessees and Lessors also of Collieries and Mines the vital
importance of giving the proposals, embodied in the document referred
to, their best and most favourable consideration. The period has
hardly arrived for the Committee to venture a conclusive opinion as to
the most eligible mode of raising such funds as may be requisite to
erect such an Institution, on a highly respectable and thoroughly
independent foundation, and to secure its permanent utility when so
established. But they may express their belief that such support
cannot be safely left to spontaneous liberality. It appears to them,
on the contrary, desirable that the wealthy and influential interests
engaged ia the great trades of raising, manipulating, and shipping the
coal, lead, and iron, with which these counties abound, in all the
forms and combinations which these materials are capable of entering
into or assuming, together with such friends to the undertaking-, out of
these districts as may be disposed to aid it, should join in procuring
either a Charter or an Act of Parliament, of such a nature as would, for
a given number of years, secure the accruement of the funds necessary to
give prosperity to the Institution, as well as such smaller permanent
pecuniary aids as might, in future time, be essential to the entire
utility and vitality of such an establishment. Your Committee, on the
present occasion, deem it their duty to express generally, their warm
approbation of the scheme, as sketched in the Report of the Council of
Mining Engineers, and their hope that the great body of the Coal Trade
will aid their efforts to promote, by a resolution this day, this great
undertaking, for which all opinions seem to concur in pronouncing this
locality to be peculiarly adapted by circumstances as well as by nature,
btit which is, in itself, of national rather than local importance.
Resolved,—That the meeting concurs in the Report of the Mining
Institute, and in the opinion of the Committee of the Trade, that it is
highly desirable to establish a College for the Advancement of Practical
Mining and Manufacturing Science at Newcastle, a locality so well
adapted for that purpose, and strongly recommend the Trade to support
the same : and the meeting is further of opinion that the Lessors of
Mines
225
and the Mining Interests generally of this and other portions of the
Kingdom, as well as the Government, should be applied to for support to
such Institution, the object of which appears to the meeting one of not
merely local but of national importance, bearing as it does upon
increased skill and economy in production, and also upon the due
security of life and property.
The Chairman briefly added, that there could be but one opinion in
reference to the very flattering- report and resolution just read. With
respect to the recommendation that the Institute should proceed to
canvas the rest of the trade in other districts, that was a subject
which he considered should be left entirely in the hands of the Council,
in order that they mig-ht take such steps as they deemed necessary to
prosecute the object. He understood that the question will be brought
before the whole trade in London in the month of March next.
A brief conversation then ensued in which the following g-entlemen took
part:—Mr. Atkinson, Mr. Hall, Mr. Longridge, Mr. M. Dunn, and Mr.
Barkas. The purport. of their remarks were all in favour of the College
: also, of the necessity of moving- forward cautiously and securely, and
of the further progress of the scheme being left in the hands of the
Council of the Institute. Ultimately the following resolution was agreed
to —
Resolved,—That the Council be requested to take such further steps in
the prosecution of the plan for the establishment in this town of a
College of Mining Science as they may deem requisite, the Council laying
before a subsequent meeting of the Institute a report of what has been
done.
The Secretary next read a letter from Mr. Boyd, the treasurer, relative
to the difficulty he had in getting- the subscriptions in from the
different collieries; but after some conversation on the subject the
Secretary was instructed to write to Mr. Boyd, stating- that he must
take the best means possible to accomplish his purpose.
A letter was read from Mr. Marley, of Bishopwearmouth, relative to the
safety cag-e of Messrs. Grant and Co., which g-ave rise to some
discussion as to its relative merits.
Mr. Hall intimated that he had taken some trouble to introduce Grant's
cag-e with its g-rips to the notice of the members of the Institute, and
got the model in the room for inspection, showing- the mode of putting-
on the grips to the cage. Several gentlemen, however, seemed to think
that the risk incurred with the grips would be greater than the benefit
they were likely to confer on the workmen, and especially in regard to
deep pits, where great speed was required. It was contended that the
226
grips or guides in the shafts could not be kept constantly in order. Mr.
Thomas "Wood, ofThornley, and others, had tried them. They found them
similar to Fourdrinier's plan of grips j and they thought that if
Grant's were generally in use it was possible that the loss of life
might be more with them than without.
A discussion then ensued, some contending that their use were
questionable, while other members stated that they knew instances in
which it had been instrumental in saving the lives of workmen. Mr.
Anderson' narrated one or two facts illustrative of their safety, and
Mr. Dunn, government inspector, adverted to an inquest or two at which
he was present, where parties had been killed by falling down the shaft
by some accident occurring to the rope, and stated it as his opinion
that had Grant's cage been at the pits in question the men's lives might
have been saved.
Mr. Longridge deprecated the propriety of arriving at any definite
opinion on the subject, as it was irregular; beside, it would be very
injudicious for the Institute, as a body, to give any opinion as to the
merits of the cage. Individual members might give an opinion regarding
it, but the Institute ought not to commit itself in any such way.
Several other members coincided with Mr. Longridge, and as Mr. Dunn had
paid some attention to the subject, it was suggested that he would,
perhaps, hereafter draw up a document and submit it to the Institute for
discussion.
Mr. Dunn having assented to such a course, the following motion was then
passed in reference to the letter of Mr. Marley :—
That the Secretary be instructed to inform Mr. Marley that the members
of the Institute must decline giving-, as a body, any opinion an the
merits of Messrs. Grant's cage, but are ¦willing', if the subject be
brought forward before them to discuss it, to elicit the opinions of
individuals.
The Secretary then announced that the next subject for discussion was
the paper of Mr. Reid, " On Practice with Gas at Blowers."
Mr. Hall had no objection to such a course, but he submitted that the
discussion on his paper should be resumed, as Mr. Dunn said that he
thought the subject had not been sufficiently discussed. Up to the
present he had every reason to believe that his paper, together with the
map of the coal-field, were correct, as no one had yet pointed out any
errors in them.
The Chairman thought if such a course was in order, the members might as
well proceed with Mi'. Hall's paper, so that it might be finally
227
disposed of. For himself he thought the paper had been fully discussed ;
but nevertheless, if any one had anything to add, the meeting would be
glad to hear him.
Mr. Longridge thought it very desirable for any one to point out if they
could, any error in Mr. Hall's paper, as the value of it depended upon
its accuracy.
The Chairman after a pause, finding that no one was inclined to say
anything, submitted the propriety of adjourning the discussion on Mr.
Reid's valuable paper, inasmuch as both the President and Mr. Taylor, as
well as other members, were absent.
This having been agreed to, the meeting broke up.
229 NORTH OF ENGLAND INSTITUTE
OF
MINING ENGINEERS.
MONTHLY MEETING, THURSDAY, MARCH 1, 1855, IN THE ROOMS OF THE
INSTITUTE, WESTGATE STREET, NEWeASTLE-UPON-TYNE.
Nicholas Wood, Esq., President of the Institute, in the Chair.
The Secretary having- read the minutes of the proceedings of the
Council, the following" gentleman was elected a member:—Mr. J. L.
Simpson, Blaydon Burn.
The President then informed the meeting that he had received a copy of
Mr. Greenwell's work on Mine Engineering-, as a present to the
Institute. The work was most excellently got up, and the least they
could do in return was to pass a vote of thanks to that gentleman. He,
therefore, begged to move a vote of thanks to Mr. Greenwell.
Carried by acclamation.
The President then intimated that the next business before the meeting-
was to discuss the merits of papers that were in arrears, and in
particular that of Mr. Hall's, Mr. Longridge's, and Mr. Reid's. With
respect to the latter paper it had long been before them, and he
supposed the members would be quite prepared to make some observations
upon it, and with that object he should be glad to hear any observations
thereon. He thought there were some things in Mr. Reid's paper which
were very useful, and some which required consideration. In the first
place he asked Mr. Reid if he had anything further to explain 1 Vol.
III.—March, 1855. h h
230
Mr. Reid.—No; the paper was wholly composed of facts, and
therefore it contained little or no theoretical matter.
Mr. Atkinson ohserved that as there appeared one point in Mr. Reid's
paper rather remarkable, he begged to call attention to it, as he was
inclined to think that Mr. Reid was in error. The point he referred
to was at page 38, where some particulars were given relative to the
effects of a blower of gas. The conclusion arrived at was that the
pressure of the gas was 67§Tbs. per square inch, or 4J atmospheres.
This amount of elasticity, he considered, was based upon erroneous
grounds. Mr. Reid> in his paper, assumed that in two air-ways
opposed to each other, the pressure, to be in equilibrium must be
greater in the one area than the other, in the inverse ratio of their
areas; but the only way, in his (Mr. A.'s) opinion, to arrive at the
real pressure of gas exerted, was to ascertain the velocity with which
it issued from the gullet, and to calculate the force required to
produce such velocity. Mr. Atkinson then explained his views on the
subject as follows :—
"It is presumed that the pressure per unit of surface exerted by the gas
on an area of 12 feet, opening into an air-way with an area of 54 feet,
must have been such as that the product found by multiplying the
pressure per unit of surface exerted by the gas, into the area through
which it passed into the air-way, must have represented a gross pressure
on the entire area at least equal to the pressure of the atmosphere in
the air-way multiplied into the area of the air-way itself, because the
pressure of the gas overcame that of the atmosphere.
" The above conclusion is not in accordance with the laws of nature, it
being a fact that the slightest excess of pressure per unit of surface
exerted by the gas over that of the air coming towards it, would suffice
to enable it to "back" or penetrate into and mix with the air.
" What is termed the hydrostatic paradox, or what may here be termed the
pneumatic paradox, is brought into notice:—the gross pressure
distributed over the entire surface is not the criterion whereby to
determine the pressures, all that requires consideration is the pressure
exerted on each unit of surface by the gas and the air respectively,
whichever of them exerted the greatest pressure per unit of surface
would prevail against the other, quite independent of the areas over
which they operated *, no data appears to be given in this case, whereby
to decide to what amount the pressure per unit of surface, exerted by
the gas, exceeded that exerted by the air.
231
"At page 41 a similar error is fallen into, and because it is presumed
that gas escaped out of a gullet of 1| feet area, at such a pressure as
to back the air in air-ways of 36 feet area, besides filling a staple in
the return having 40 feet area, the mistaken conclusion is arrived at
that the pressure per unit of surface exerted by the gas must have been
\-f = 60*8 times as great as that exerted by the atmosphere, giving*
thus the incredible pressure of 9123bs. on the square inch, as being due
to the escaping gas. "Although the data furnished in the latter case are
not such as to enable us to determine the pressure at which the gas
might exist in any reservoir from which it might escape, if it happened
to have to force its way through long' and narrow channels before
reaching the gullet by which it escaped, yet they are such as to enable
us to determine with some degree of certainty the actual pressure at
which the gas really escaped from the gullet.
" The velocity with which the gas escaped, according to the data
furnished in the paper, is 37,634*4 feet per minute, and this velocity
would require a head of 6115*5 feet of gas column to generate it- see
[10], in my paper on ventilation, page 78.
"The density of the inflammable gases in coal mines in this vicinity may
be taken to be *63, that of air at the same temperature and density
being 1, and at an averag*e temperature and under atmospheric pressure
will therefore weig'h about *047Ibs. per cubic foot, and hence the
pressure due to the velocity of the escape of the gas from the gullet
would be 6115*5 x '047 = 287*4281bs. per foot, or nearly 2fbs. per inch
above the pressure of the atmosphere or medium into which it escaped, so
that the conclusion as to its being 912 — 15 = 897flbs. per square inch
above that pressure is evidently very much over-rated."
Mr. Greenwell supposed that Mr. Atkinson, in that calculation, did not
include the pressure necessary to overcome the friction of the gas
passing along and through the gullet ?
Mr. Atkinson—That he could not ascertain, as the gas probably existed at
a great distance from the point of issue; but if not, they must know
that according to the facts related they had the effect of the pressure
at the orifice of the gullet.
Mr. Green well—Perhaps Mr. Atkinson assumed it had issued into a vacuum?
Mr. Atkinson—No; he calculated the gas as issuing into the atmosphere.
232
The President—What has been pointed out by Mr. Atkinson was just the
same as he mentioned to Mr. Reid previously; for it did appear to Mm
(the President) that the mode of calculation adopted was not correct. In
page 41, Mr. Reid gave the area at the aperture where the gas issued at
180 square inches, and after stating the pressure at the time the gas
was passing, he further says at page 42, that
" Applying this quantity to the gullet area of the blower, and assuming
the time of its exuding at one minute, we have the apparent velocity of
gas escaping per«quare inch of surface in that time equal to 261-35
feet, or at the amazing rate of 37,G34-40 per square foot of area."
This mode (continued the President) of calculation was incorrect. He
thought the correct mode was to ascertain the force required to produce
the velocity, which, was stated, through an aperture of an area equal to
tliat through which tlie gas issued. Mr. Reid seemed to have calculated
the number of atmospheres which was required to check the current of air
passing along the drift, and it was stated that the gas forced the
current of air in an opposite direction: this would, no doubt, require a
considerable force; and the real question certainly was—What was the
force required to do that? as this would be an element in the
calculation of the force required to cause the gas to issue from the
gullet or blower
at a definite velocity.
Mr. Greenwell—Besides, another point to be considered, was the
increased pressure due to the length of the orifice or channel through
which the gas passed. It was assumed that the gas merely passed
through
a thin orifice into the atmosphere, whereas the blower passes through
crevices of an unknown length.
Mr. Atkinson included all that in his first statement. There was no
other data to determine the force which existed at the mouth of the
orifice except the velocity with which the gas issued.
Mr. Bark as observed that in every case of blower coming suddenly off,
if with great force, he always found it to back the current of air,
which he supposed arose from the different densities of the gas and the
atmospheric air. He did not know whether gas would have the same effect
as if it was atmospheric air coming off with the same velocity, as there
was the effect of the difficulty of the gas and the atmospheric air to
mix together, he thought the mode of calculation adopted by Mr. Atkinson
was the correct way of getting at the velocity. Taking all the elements
into consideration, the question required considerable thought, as they
233
would find that there was a great\deal in the manner in which the gas
was evolved.
Several other brief remarks were made by one or two members of similar
import to the foregoing,—after which
Mr. Reid briefly replied in general terms to the remarks of Mr.
Atkinson, by stating that he was not then prepared to go fully into the
point at issue without considering the subject more carefully. One thing
he would admit, and that was that his calculations on the actual
pressure of the gas were made from simple facts,—he did not pledge
himself to the absolute correctness of the figures given, but he must
say that so far as he could judge at present, he could not agree with
Mr. Atkinson that the pressure which he assumed could produce the effect
which was observed. As regarded gas issuing into free space that was
entirely a different thing. He was not then prepared to go further into
the subject, but would take it up some other time.
Mr. Barkas stated he had a case at Waldridge Colliery, and which he
believed was not a very unfrequent one, where the force of gas raised
the thill or pavement of the mine about a foot or upwards of solid rock
or shale.
The President suggested that the same plan which was observed at the
Civil Engineers' proceedings might be adopted by that Institute, which
was that at each succeeding meeting the minutes of every previous
meeting were read over, so that if any gentleman had any further
observations to make on any given subject he could do so, and time was
given for consideration. If such a scheme was adopted they might come at
the end of the succeeding month prepared for the subject in discussion.
Their object was only to elicit the opinions of members, and to arrive
at sound and correct conclusions upon the questions at issue. Mr.
Atkinson contended that Mr. Reid should measure his force by the
velocity at which the gas issued from the aperture. Mr. Atkinson's
remarks, however, would be printed, so that by the next meeting the
discussion could be resumed.
The subject then dropped, with the understanding that it be hereafter
resumed.
The President next called attention to the paper of Mr. H. G. Longridge,
and stated that for himself he thought it one of great importance, as it
referred to the probable supply of coal to the fleet now in the Black
Sea, and to steam vessels hereafter employed in the trade of that part
of Turkey and the Danube, and therefore he should be glad to
234
receive any further information on the subject. It was stated in the
newspapers that the mines alluded to by Mr. Longridge were in operation,
under the superintendence of Mr. Berkley.
Mr. Longridge in reply said, that his paper contained a statement of
facts: that he had no further particulars to coxnmunicate, but would be
most glad to answer any questions. With regard to any further
information, that would be found in the papers published before
Parliament.
The President—But that did not contain more information than they had in
his paper.
Mr. Longridge—He knew that directions had been given to open out the
second valley alluded to in his paper, from whence the Government were
going to draw a great part of the supplies.
The President understood an arrangement had been made with the Turkish
Government, and that it was intended to supply Her Majesty's fleets from
these collieries.
Mr. Longridge—Yes, it was computed they would be able to get upwards of
35,000 tons per annum: but before they could do so, they would require a
great number of labourers..
The President—Did the papers before Parliament state the specific
quality of the coal ?
Mr. Longridge—Not very particularly; but experiments had been made on
the spot at the request of the Government, and the report to the
Admiralty was to the effect that the quality of the coal was suitable
for steam purposes, but it was not so good in quality as the coal in
England.
Mr. Hall thought it was found that the coal got harder as it approached
seaward.
The President then remarked that, in a commercial point of view, coal
obtained at the Black Sea was of great importance to this country, as,
if coal could be got there at a cheap rate, it could not fail to
facilitate commerce between this country and Turkey. What really wanted
was, cheaper coal at such distant places, which would tend to assist
rather than operate against the coal trade of this country.
The meeting then broke up.
235 NORTH OF ENGLAND INSTITUTE
OP
MINING ENGINEERS.
MONTHLY MEETING, THURSDAY, APRIL 5, 1855, IN THE ROOMS OF
the institute, westgate street, newcastle-upon-tyne. Nicholas Wood,
Esq., President of the Institute, in the Chair.
The minutes of the Council having- been read by the Secretary,
The President laid before the meeting1 a section of the coal and
ironstone measures of the county of Lanarkshire, in Scotlond, presented
to the Institute by Mr. Moor, of Glasgow.
It was resolved that the thanks of the meeting be given to Mr. Moor, and
that the President be requested to convey the same to that gentleman.
A letter was read, addressed to the Secretary, by Mr. John Weale, the
publisher, of High Holborn, London, stating that the annual expense of
advertising" the Transactions of the Society, in certain publications,
of which he proposed to send a list, would averag*e ten pounds or
thereabouts.
It was resolved, that Mr. Weale be empowered to expend the above sum
annually on advertisements, and that he be requested to transmit the
list of publications promised.
It having been suggested that the hour of two o'clock was too late for
holding the general meetings of the Society, and that one o'clock would
probably be a more convenient hour; it was agreed that the notice of the
Vol. III.—April, 1855. i i
236
members be directed to this alteration, with a request that they would
consider the same, and come prepared to the anniversary meeting to
arrive at some determination thereon.
The President then read to the meeting a letter addressed to him by Mr.
P. S. Reid, on the objections brought against some of his calculations
of the force by which explosive gasses issue from fissures in coal
mines, as given in his Paper to the Institute in November last; and
suggesting, as he was unable to attend the meeting from illness, that
the further discussion should be postponed until he could be present.
It was arranged that the further discussion of the Paper be deferred
until the next meeting of the Society, and that Mr. Reid and the members
be apprised thereof accordingly.
Agreeably to the suggestion of the President at the last meeting, that
Mr. Atkinson should draw out, for the consideration of the Institute,
some practical deductions from his elaborate Paper on the " Theory of
the Ventilation of Coal Mines," to further the discussion on that Paper;
Mr. Atkinson presented a paper containing the different heads under
which he proposed the discussion should be conducted—such heads
presenting practical deductions from the theoretical disquisitions in
his Paper.
A discussion then took place as to the best mode of proceeding on such
an important subject, and it was ultimately arranged that Mr. Atkinson's
paper containing the heads for discussion be laid upon the table of the
Institute, that the attention of the members be called by an early
circular to the fact, and that the members be informed that the
discussion will take place at the next meeting in May, and be continued
until the subject be fully discussed.
The President observed that, as Mr. Atkinson s Paper contained the
entire theoretical exposition of the ventilation of coal mines^ than
which nothing could be of more interest to the society; and as they were
essentially a practical body, it was advisable, indeed if not absolutely
necessary, that, in the first place, the theoretical conclusions should
be thoroughly investigated; and next, and most important, that the
application of that theory to practice should likewise be carefully and
fully considered, so that they might elicit some useful practical
conclusions on the subject; and as the subject was of such importance he
trusted they would have a full meeting, that as much as possible of the
practical knowledge of the Institute should be brought to bear upon the
discussion.
The following members who had been proposed at the last monthly
237
meeting were ballotted for, and unanimously elected, viz. :-HenrV Wil
nriBf^MfeSK near Stockton-on-Tees; John Vaughn, of MiMesbro', near
Stockton-on-Tees; John Straker, of North Shields
The President then proceeded to read his Paper on the "Conveyance of
Coals Underground in Coal Mines," after which the meeting adjourned to
the first Thursday in May, at two o'clock.
239
ON THE
CONVEYANCE OF COALS
UNDERGROUND IN
COAL MINES.
BY NICHOLAS WOOD, ESQ., C.E.,
PRESIDENT OF THE INSTITUTE OP MINING ENGINEERS.
The subject of the conveyance of coal underground in coal mines from its
separation in the mine to the bottom of the pits is of great importance
to the coal trade. The increased cost, above that of the conveyance of
coals, and other minerals, by railways on the surface, demand the
attention of every one connected with the management of mines, with a
view of ascertaining if such cost can in any manner be lessened.
In the year 1825, I published a practical work on the subject of " The
Establishment and Economy of Railways" on the Surface, which,
subsequently, went through another edition, published in 1831, and the
great progress which railways, and the motive power employed upon them,
since that period has undergone, raises a very important question
whether such improvements have been adopted in the conveyance of coals
underground, and whether sufficient attention has been paid to the
subject or not.
There is, however, a wide difference in the circumstances of the two
cases—surface railways can be levelled and made of uniform inclination
at comparatively small cost to that by which they can be made
underground—the latter is, in fact, entirely tunnelling—more even than
that, as in the first formation of a road underground the coal is seldom
of sufficient height to allow of horses to travel, or for the use of the
requisite carriages : and, consequently, the dimensions of the
excavation must be
940
enlarged even before any attempt is made to make the road of an uniform
inclination, or to adapt it to any particular description of motive
power.
And when it becomes necessary to level up depressions and to take off
undulations, then it is very expensive tunnelling in solid rock;
sometimes excessively hard and extremely expensive, but always
presenting- very much greater cost than a similar process on the
surface.
And it must also be borne in mind, that there is this difference between
making roads underground and on the surface—that in the latter case,
perfect levellings can previously be obtained of all the undulations of
the surface, and this before any expenditure at all is incurred, and a
line of railway thus fixed upon or adopted, which can be formed at the
least possible cost. In underground mining or tunnelling, it is all in
the dark, we can only guess atrthe undulations before us; and,
therefore, when a certain direction or course is assumed, and which is
expected to produce the requisite degree of inclination, the undulations
in the strata, or breaks up and down by dykes, often thwart all our
calculations. The perfection of a railway is, we presume, that between
two points it should be as level and as straight as possible, if the
amount and weight of the traffic is the same in both directions; or, if
there is a preponderance of traffic in either direction, then that the
inclination should be such as to present the same resistance to the
motive power in both directions.
In mining engineering, if the ruling principle laid down be that the
road should have a certain inclination, either that it should be just
water-level, or such an inclination as that the water will just flow
from the workings to the pumping shaft, or that it should be such an
inclination as that the resistance to the load should be equal in both
directions; then if there are any undulations in the regularity of the
strata, or bed of coal— [and in every mine such undulations are very
frequent, and sometimes very considerable]—then it will be found that to
preserve the requisite levels the road, instead of being straight,
assumes the most tortuous shape; and in cases where the roads are
numerous, and where the levels or roads of two or three beds of coal are
laid down upon the same map, they assume very much the tortuous
appearances of the gyrations of the animal-cula exhibited in an oxyhydra
lens.
The formation of the roads underground approach more nearly to that of
the formation of a canal through a hilly country, with this difference,
that in the formation of a canal on the surface, the engineer can make
surveys to regulate and guide the line he may take in its formation,
whereas, a mining engineer has to form his canal without being able ever
HI
to see beyond that part of the road in which he is immediately engaged
in forming.
The beds of coal, also, are generally from three to four, or five feet
in thickness, probably the average about four feet: and the height
required for horses or machinery about six feet when finished. The rock
above or below the bed of coal is generally extremely expensive to
excavate, and hence any extra quantity of rock to be taken up or blasted
down, beyond that which is absolutely necessary, is very expensive.
Vertically, the whole space to operate on is about four feet.
The draining of a mine is, likewise, generally an expensive operation.
When, therefore, a pit is sunk, and the pumping- apparatus attached, it
becomes of great importance that as large an extent of mine should be
drained as possible. The first operation, therefore, generally is, to
push away right and left, what are called the water-levels of the
colliery, viz :—¦ drifts, adits, or levels, with such an inclination
only as that the water will just run towards the bottom of the pit, and
these are pushed or extended across the whole extent of the royalty,
from one extremity to the other, in the water-level line of the strata
or bed of coal, by which all the coal on the rise side of the water
levels are drained.
These, as before explained, are generally extremely tortuous, if the bed
of coal at all undulates. For the purpose of merely water-levels, this
is not of very much consequence; but these levels being at the lowest
point at which the seam is opened out, they are very often made the main
roads also, whereby the coals are brought out to the bottom of the pit.
In the early period of coal mining, and up to a comparatively recent
period in the best managed districts, and, indeed, in the present day in
those districts where the stimulus given by the improvements of surface
railways has not reached, it is found that almost universally the levels
which drain the mine are the horse-roads by which the coals are brought
out from the workings to the bottom of the shaft. The coals from the
rise parts of the mine being brought down to those levels or roads.
Where the mines are extensive, and where the expense of lifting the
water is costly, or where they are drained by day levels, the greatest
care is taken in making those levels as flat as possible, barely, or
just sufficient inclination for the water to find its way to the pumping
shaft or adit, and the horse-road being- either formed on the
water-level, or on a road driven parallel thereto; this circumstance
operates very materially in determining- the description of road by
which the coals are brought out, and the kind of motive power to be
employed thereon.
U2
In the early period of coal mining likewise, and prior to the
introduction of mechanical machinery to pump the water, the coal was
drained by adits into the sides of the hills—there it became of great
importance to adhere to the water level of the strata in draining the
mine, and when, even at a later period, machinery was introduced to
drain the mine, this was only able to be performed to a certain
extent,—and to the extent to which this drainage could be performed it
became of equal importance that, as the miners termed it, " no level
should be lost," but that the levels should be driven strictly water
level; and even at a late, and up to the present period, the same rule
holds good, viz :—that the levels should be driven strictly water level,
hence the coals having to be brought out towards the entrance to the
mine on such a gradient, and the load being consequently all in one
direction, the motive power is not equally balanced, but greater in the
direction of the load than with the empty carriages. Thus, the
main-roads for bringing out the coals to the bottom of the pits or
adits, may be said to be the water-levels of the mine, the cross-roads
bringing the coals from the rise to those roads, and when the
stratification of the mine is sufficiently inclined, or the beds lay at
an adequate inclination, then the coals are brought down to the
main-levels by self-acting planes, and so to the bottom of the pits.
The earliest attempt, therefore, to work coals no doubt began in digging
it out where exposed to the surface, or where the beds cropped out to
the surface, by adits or levels driven in the direction of the beds
water level, the same level or adit answering the double purpose of
drainage and a road to bring the coals out.
We have no records of how or in what manner the coals were brought out
to the surface before the introduction of railways. We know that even
within the last thirty years coals were carried out to the surface in
Scotland by women who were called " bearers," and who carried out very
heavy weights of coal in panniers, much the same as the fish is carried
by the fisherwomen, and where pits were necessary, steps were placed
within the area of the shaft which the women ascended with their load of
coals. It is probable also that barrows were at one period extensively
used for conveying the coals to the mouth of the adit, or to the bottom
of the pits, and that where the floor of the mine was soft, planks were
laid down whereon to wheel the barrows• and likewise, before the
introduction of railways, sledges were used in which the baskets or
corves were placed which contained the coals. In this case, also, where
the floor of the mine was soft planks were used. These latter roads
were likewise called "bar-
243
row-ways," which would indicate they were the same description of roads,
and used for the same purpose as the roads where barrows were used. To a
comparatively recent date sledges were used in the pits on the main
roads, and likewise on the surface at the top of the pits to convey the
coals from the mouth of the pit to the screens, or to the waggons used
to convey the coals to the shipping places.
In those districts where early mining* has been practised we find the
pits very shallow and very numerous. The earliest working having been
by adit as before named, and the powers of drainage being at those
periods very inefficient, the pits would necessarily be very
shallow, limited to the power of raising the water of the mine. And
when the mode of conveyance underground was confined to barrows,
numerous pits would be requisite to be sunk to supply the deficient and
expensive system of conveyance. As the system of conveyance was
improved, even by the introduction of sledges, the necessity for sinking
pits would be less; but even up almost to the end of the last century,
the number of pits sunk was very numerous; although, perhaps, the
question of ventilation may, in some cases, have regulated the frequency
of sinking-. Horses were, no doubt, used for a long period in the
shallow pits for drawing the coals to bank by gins; but the depth to
which they could raise the coals was, though limited, very much beyond
that of manual labour.
The next process was, probably, the use of water-wheels, wherever such a
power could be applied; and hence we find that water-wheels were used at
and up to a not very distant period, both for the drainage of the mine
and for drawing the coals to bank. And such appears to have been the
reluctance to part with an old friend, that long after the introduction
of the steam engine, the latter was, in many cases, employed to pump the
water up to the requisite height, to be afterwards used in working the
water-wheel.
In some of the mountainous districts of Wales, water-wheels are indeed
still used; and the use of water has been carried to a much greater
extent than it can be carried in this manner, especially in South Wales,
by the use of what are called "Balance Pits;" where water is run into a
bucket attached to a rope ov chain passing over a pulley at the top of
the pit, of a greater weight than that of the coals, or weight to be
drawn up the shaft, and which is attached to the other end of the rope
or chain. The water descending thus draws the coals up the pit ¦. the
water is then emptied at the Vol. III.—April, 1855.
k k
244
bottom, the loaded tub of coals placed over it, and they are then drawn
up the pit by another and similar process. The water generally runs out
to the surface by adits; but in some cases it has to be lifted either by
water-wheels or by steam engines. Coals are thus drawn to bank up pits
of a depth of 60 to 80 fathoms.
These observations though not, perhaps, strictly applicable to the
subject of this paper, are not entirely irrelevant thereto, as the
powers of raising tbe coal to the surface, and, consequently, the number
of openings in a given area, modify and determine, to a considerable
extent, the means and tbe mode applied to convey the coals from the
workings to such openings. Hence we find in the early stages of the
working of coalmines the roads were made from the adits, and from pit to
pit, in the water-level line of the coal, draining and cutting off a
strip of coal nearest the surface at the least possible cost and labour.
Successive strips were then drained or worked more and more towards the
dip of the mine, or at greater depth from the surface, as longer and
more expensive adits were driven, or as successive improvements
advanced, and more power was applied to lift the water and to raise the
coal to bank.
Hence it was then the system to commence the winning and working of the
mine at the extreme rise part of the coal-field, with successive
drainage, and working deeper and deeper, as more power was obtained.
This is most clearly exemplified in the valleys and in the hilly and
mountainous coal-fields of Great Britain, and especially in the hills of
the extensive coal-fields of South Wales. The successive deeper levels,
being almost an index of the development of the continuous advancement
in science and in the improvements of machinery.
Now, when we may almost be said to have attained such a degree of
perfection in machinery and in engine power to almost, if not quite,
command the drainage of the deepest part of any of our coal basins, [as
the coal measures being the uppermost beds of the series of rocks on
which they repose, the coal does not extend to a very great depth from
the surface in the coal fields of Great Britain], and when we can,
consequently, place the draining pit, or drawing shaft, in the deepest,
or in any other part of any coal field or royalty; we are, consequently,
enabled so far as the number of openings to which the coal is to be
conveyed underground extends, to place such openings at that point of
the coal-field to which the coal can most advantageously be conveyed. —v
This very circumstance, as the natural effect of such a command
of
245 i
power involves, however, has been the cause of much deeper openings
being made,—more expensive, and, consequently, less in number; and,
therefore, requires that the coals should be conveyed a much greater
distance underground than heretofore.
While, therefore, in the early stages of coal mining, the openings were
never more than a hundred, or two or three hundred yards apart,
increasing in distance as improvements of winning, draining, and
conveyance of the minerals advanced; and even up to within the last
half-century, the pits were never more than half a mile or so distant.
And though the ventilation of the mine in some degree regulated the
distance, like the other improvements in the science and px'actice of
mining, ventilation was improved in the same ratio and kept pace with
the other requisites of more extensive mining operations. Now, at the
present time, the distance of the pits or openings from each other in
the deep mines, are as many miles as they were hundred yards apart in
the early period of coal mining. And we consequently see the
necessity and importance of the consideration of the means and economy
of conveyance of the coals underground in the present extensive system
of mining operations.
Having thus given a general outline of the progress and successive
increased means of the conveyance of the coals underground, and having
pointed out the difficulties attendant on underground operations as
contrasted with similar operations on the surface, I shall now enter
into the detail of these different modes practised during the successive
periods up to the present time. I shall then investigate the powers of
each mode, or the motive power employed, which I shall illustrate, as
much as possible, by experiments and diagrams; and I shall then
endeavour to produce some practical results from the enquiry.
It is unnecessary to enter into the minutia or detail of the conveyance
of coals by barrows, or by sledges, or even by the more repugnant mode
of carrying the coals on the backs of ladies. All these modes are only
matters of history, except where the seams are much inclined, and where
sledges are used to convey the coals from the face of the workings to
the main roads, which I shall now shortly describe.
On the Continent, viz :—in France, Belgium, and Prussia, where the beds
of coal are much inclined to the surface, and where the inclination is
such that the coals will not slide down the floor of the mine into the
main roads, and in some parts of England and Wales also, in similar
situations, sledges are used to convey the coals from the face of
246
the workings to the main roads, and the coals are either packed upon the
sledges, and by them conveyed to the bottom of the pit7 or emptied into
the tubs by which the coals are conveyed along the main roads to the
bottom of the pit or to the mouth of the levels.
In these cases the main roads are formed along the water-level course of
the coal, and at short distances from each other in the rise of the
beds^ between which the coal is generally taken away by the long wall
system, in one process, the entire width between the two roads; or it
may be worked by the pillar and wall system, the pillars being generally
taken away and brought to the same headway as that by which the whole
coal is worked, and as the work proceeds to the rise the coals are
brought to the lower levels by self-acting inclined planes. Boys are
generally employed for this purpose.
Sledges, as before stated, were also used very extensively in the main
roads in the more flat mines of England and Wales to carry the coals,
from where worked in the face, to the pit, which were drawn by ponies 5,
and when the beds of coal were thick horses were used. These sledges
were dragged along the bottom or thill of the mine where it was hard,
but where it was soft deals or planks were laid down, or penning-,
composed of narrow pieces of wood laid across the roads, and these were?
as before stated, called in the districts of Northumberland and Durham "
barrow-ways."
In these cases one pony, or one horse, was always employed to drag one
basket or corf of coals at a time, and, consequently, as may be
presumed, and indeed as was the fact, the expense was considerable;
hence the necessity, when the beds of coals were not at a great depth
from the surface, of having frequent openings or pits, by which the
coals could be drawn to the surface.
The next step was the employment of wheel carriages, which ran upon
timber roads, or railways formed of timber. The carriages had wheels
similar to our tram wheels, running upon the flat wooden rails, with a
ledge on one side, (similar to the cast iron plate rails), to keep the
wheels upon the road. But cylindrical wheels, running on wooden roads,
similar to the old ledge wooden railways, were likewise used. The wheels
were originally of wood with wooden flanches, but subsequently a flat
bar or hoop of iron formed the periphery of the wheel, with a plate of
iron to act as the flanch of the wheel.
These wooden rails and railways, have, like similar railways on the sur-
247
face, now given way to cast or malleable iron railways, either the
common tram road or the edge rail; and to carriages with wheels of
either cast or wrought iron, suitable for each description of railway.
For a long period, or z*ather down to a very recent period, tram roads
with the tram wheel were universally used in this district, but they
have now been, if not quite, almost universally superseded by the edge
or round top rail. In some districts of England, Wales, and Scotland,
however, the tram road is still in use, a prejudice still existing
against the use of the edge rail. In most of the iron works in Wales and
Scotland, the underground railways are tram roads, with wheels loose on
the axle, and constructed so that when a wheel breaks it can easily be
replaced.
Up to a recent period also, in the Northumberland and Durham districts,
the coals were drawn to bank by baskets or corves. These were placed
upon the sledge (when sledges were used), and brought out to the bottom
of the pit, were then attached to the rope, and drawn to bank, leaving
the sledge at the bottom of the pit. The corf, or basket, was then
placed upon another sledge at bank, and so conveyed to the screens or
wagons, and the coals emptied out, the empty corf, or basket, having, in
the meantime, been ag'ain sent down the pit.
In many of the pits in the Midland districts, in Scotland and in Wales,
the coals, especially where they are hard and larg'e, are placed on and
and packed upon the sledg'es, or trams, or waggons with iron rings, and
are so drawn up the pit, both trams and coals. In these cases, however,
it is necessary to have guides in the shafts to prevent the trams, or
carriages, from striking the sides of the shaft, and from striking each
other in passing at meeting in the shaft. Great weights are generally
drawn at a time, and the motion or velocity in drawing' the coals to
bank is extremely slow, the principle being to bring to bank larg*e
weights at a slow speed.
The contrary is the practice in the North of England, the pits being
generally of a much greater depth. The principle is to draw
comparatively smaller weights up the shaft but at great rates of speed.
And though this practice is more particularly applicable, perhaps, to a
comparatively recent period, it is now customary to draw to bank, at one
of the pits in the North of England, as many coals as are drawn to bank
at two or three of the pits in the Midland Districts or in Scotland and
Wales.
It may, however, be remarked, that in the latter localities, the
working's
248
have not yet penetrated to such great depths as the workings in the
Newcastle District have done, the necessity has not, therefore, yet
arisen, as a measure of economy in the latter case, to have fewer pits
and to bring1 larger quantities of coals to bank at each pit. Still,
however, when the greater expense of conveying coals underground as
compared with that of the conveyance of coals on the surface is
considered, it will, in some cases, be found to be more economical to
have more pits with a less distance to convey the coals underground,
than fewer pits and a more extended conveyance underground.
It was, for a long time, deemed inconsistent with the principle and
economy of drawing coals at a rapid rate up the shafts in the North of
England, to adopt the system of the Midland Districts of drawing the
coals along with the tubs or carriages up the pits, especially when
combined with greater comparative weights, and with the system of guides
or slides. Ultimately, however, the mode of drawing both the coals and
carriages to bank was adopted in this district, and with it, of course,
the system of slides in the shafts. And such has been the rapidity of
conversion to this system, that, at this time, I do not believe there is
a single colliery where this system is not adopted, and the old plan of
drawing the coals to bank in baskets or corves is not abandoned.
While baskets or corves were used the system of conveyance of the coals
underground was to employ small carriages called trams, usually running
on plate rails, but sometimes on round or edge rails. The coals were
thus brought out from the face of the workings to the main roads by boys
which were called " putters," (and here it may be remarked, that even
after the tram or plate, and the edge railways were introduced, these
roads were still designated " barrow-ways,") the corves were then lifted
by small cranes from the trams and placed upon larger carriages which
were called " rolleys" the roads being called " rolley-ways," by which
they were conveyed to the bottom of the shaft.
In some cases, even since the system of drawing the tubs as well as the
coals to bank has been adopted, the trams or tubs are placed upon the
large carriages or volleys, which are then more generally called "
wagons" (especially where edge rails are used,) and so conveyed to the
bottom of the pit, this system has now, however, almost universally
given way to the plan of using the same tram or carriage to convey the
coals from the face of the workings to the bottom of the pit, and these
are mostly called " tubs."
249
Figs. 1 and 2, Plate 1, shews the tubs now most generally used, there
are, of course, a great variety of dimensions or forms used, either with
the wheels outside of the body of the tub or underneath, with different
sized wheels, according as the bed of coal is of more or less thickness.
It will be seen hereafter that a great advantage exists in the
employment of wheels of large diameter, and as the wheels of the tubs
which are used must, of necessity, travel into the workings, their size
are regulated by the height of the seam. They are generally only from 8
to 12 inches in diameter. On the main roads, where horses are used, or
wher e horses have to pass along, there is necessarily a greater height,
so that wheels of a larger diameter could be used, and consequently the
friction would be very much reduced, so much so that in the cases of the
tubs being placed upon wagons as previously described, the diminution is
almost, if not quite equal to the useless weight of the trams carried
upon the larger wagons. But the trouble, delay, and expense of
transferring the smaller to the larger carriages, has been considered to
so far outbalance any advantage obtained by the diminution of friction,
that the smaller wagons or tubs, though the length of the roads are
sometimes equal to two miles, are used in preference to the larger
wagons.
Considering, that no great practical result would be obtained by
enquiring into the resistance or friction, or the effect on the transit
of coals of those systems which have been abandoned, or which are only
partially in use, I have confined my experiments to the carriages or
tubs almost universally used in the collieries of the Counties of Durham
and Northumberland, though I shall endeavour to compare their effect
with some of the modes not yet abandoned in some of the other districts
of the kingdom.
FRICTION OF CARRIAGES.
It is scarcely necessary to state that in all carriages moved on
railways, with wheels, the friction of such carriages is composed of two
descriptions of resistance, viz.: that which is due to the friction of
the attrition on the axles, and that which arises from the resistance of
the periphery of the wheel upon the rail.
In my work on railroads I gave a great many experiments to ascertain not
only the entire resistance of carriages moved on railroads, but also the
amount of each of those two descriptions of resistances; and from
250
these experiments, as well as from the well known laws of mechanics, 1
have deduced some practical conclusions.
Rapid strides have since been made in the improvments of carriages upon
railways,—'but the experiments thus alluded to having- been made on the
railroads then in existence, and which were almost exclusively private
colliery railways,—and as the carriages on which these experiments were
made more nearly assimilates to those of the underground carriages now
employed in the collieries, they will be probably more useful as
illustrative of the resistance of such carriages than experiments made
upon the more improved carriages of the present day upon public
railways.
The result of the experiments above alluded to, and made on the wagon3
used on the private railways, when my work was published, was, that the
friction of such wagons was about the ^^^ part of the weight, the
rolling or resistance of the wheels on the rails being about the TJff_.
part of the weight, and the conclusion derived from the experiments then
made was—*
That, in practice, we may consider the friction of carriages moved on
railways, as a uniform and constantly retarding force,
That there is a certain area of bearing surface compared with the
insistent weight when the resistance is a minimum,
That when the area of bearing surface is apportioned to the insistent
weight the friction is in strict ratio to the weight.
There is no doubt that the friction of the well constructed carriages
now used on public railways, with self-lubricating apparatus, is much
less than the above amount. Indeed, some of the experiments then made
upon the wagons used on the colliery railways showed the entire
resistance not more than the -g-jo^ Par^ °f ^e weight. It was my opinion
then, and subsequent experience has shown that it is more safe in
practice to adopt the previous conclusion for such wagons in the
condition in which they are generally found on private railways.
In pursuing the enquiry, therefore, of the economy of the underground
railway system, I shall adopt the same course of proceeding, and not
give results derived from well-built carriages fitted up for the
occasion, but shall give experiments made with carriages promiscuously
taken from the stock actually at work at the collieries when the
experiments were made. In following this course we proceed on safe
grounds, as dependence may be placed on results thus derived in their
application in practice.
251
The following are experiments made at different Collieries in the
Counties of Northumberland and Durham on the Friction of the tubs used
at those Collieries:—
No. I .—EXP EBIMENT made in the Main Coal Seam, Hetton Colliery, March,
1855.
-J * Tirae Leo7th ™al 5? InCli"ati0n
^ot
6'fUbs ^ FaU- Yak ofP'a™ tSL
Min. Sec. Yards. Inch. Inch. lbs.
1 3 1 — 10 188 60-0 -32 1 in 125 4158
2 3 1 — 20 194 62- -32 1 .. 112
4158
3 6 1 — 20 169 58-5 -34 1 .. 104
8916 w . , , . . ™ ,
We'gnt of each Tub.
4 6 1 — 12 161 61- -3? 1 .. 95 8916
-, . '. ,flQ„,
Empty Tub .. 4631bs.
5 4 1 — 10 159-5 63-25 -39 1 .. 90 5544
Coals.......' 923 "
6 4 1 — 15 182 53-75 -30 1 .. 119
5544 Total.. 136616s. ,7 1 1 — 15 212
53-5 -25 1 .. 142 1386
,8 1 1 — 18 208 53-5 -25 1 .. 139
1386
Ave" ?28 1 — 15 184-2 58-5 -32 1 in 108 5001 rage
)
In the above experiment the gradient of the plane on which the tubs were
placed was just sufficient to put the tubs in motion, and they were
allowed to run along the plane until they came to rest, the gradient on
that part of the plane being a little less than where the tubs were set
off. The length of the plane from where the tubs were started until they
came to rest is given, as also the total fall in inches, with the rate
of inclination.
The tubs starting from a state of rest, and coming to a state of rest
again, the rate of inclination of the plane is the measure of the
friction in parts of the weight. Hence the average of these experiments
shew the friction to be equal to the T£g-th part of the weight. The
wheels, when new, being 12 inches, and the axles l-3775 inches, the
ratio being-8*73 : 1. The road was laid with rails, having a round top,
and was in good condition. The variation in the experiments arose from
the condition of the tubs, and whether well greased or not.
Vol. III.—April, 1855. l l
252
No. 2.—EXPERIMENT made in the Stone Drift, Minor East Pit, Hetton
Colliery, March, 1855.
tl ™t'\ m |Lenfth Total Fal1 Inclination
Wejht .
*S S -p, „ Time. of -p ,, per f
p, ol
o'§ Tubs Plane- Yal'd-
0tm"e- Tubs.
X ft
Min. Sec. Yards. Inch. Inch. lbs.
1 3 1—0 143-5 11-25 -78 1 in 45 4167
2 3 1 — 16 178-5 118-5 -66 1 .. 54 4167
3 6 1-20 156- 114-12 -73 1 .. 49 8322
Weight of each Tub.
4 6 1-17 189-5 121- -63 1 .. 57 8322
Empfy Tub ,, m^
5 8 1 — 21 198- 123- -62 1 .. 62
11096 Coals.......' 923 "
6 8 1 — 17 1£2- 114-25 "75 1 .. 75 11096
Total.. 1388ftSs.
7 1 1 — 20 171- 119- -69 1 .. 69 1387
8 1 1 — G 131-5 114-5 -86 1 .. 41 1387
rage \.................... 1 m 53___________________________
This experiment was performed in the same manner as No. 1 experiment,
but in this case the diameter of the wheels of the tubs was 7*5 inches,
the axles 1-3775 inch, the ratio being- 5-5 : 1, and the road bad also
been at work for some time. The tops of the rails being* quite flat, and
the road, though in good working order, not in the best, but in ordinary
condition. These experiments shew the friction to be equal to the ¦^rd
part of the weight.
No. 3.—EXPERIMENT made in the Old Polka Way Elemore Colliery, March,
1855.
-I *" Time Lenfh Total £S I.»llnafflan
""HP*]
°| Pull Time- °f Fall. t'er, of
Plane. °*
6 a Tnlis Plane. yard.
Tubs.
^ p. J-""6-
Min. Sec Yards. Inch. Inch. IBs.
1 10 1-30 153 62-25 -406 1 in 90 13860
Weight of erfch Tub.
2 10 1-30 122 55-62-45 1 .. 80 13860 ^^ ^ ., ^^
3 10 1 — 37 119 55-25 -46 1 .. 77 13860 Coals.......' 92S "
4 3 1 — 37 151 62-5 -41 1 .. 87 4158 Total. .1386
5 1 1 — 30 125i 56-45 -45 1 .. 80 1386
mge }.................... l in 82'r
253
This experiment was made in the same manner, upon a piece of road which
had been for some years in use, and where the rails were quite flat on
the top. The road being in ordinary condition. The diameter of the
wheels and axles being the same as in No. 1 Experiment, wheel 12 inches,
and axle 1*3775 inch, ratio 8-73 : 1. The average inclination of the
plane in the experiment being* 1 in 82-7, while it was only 1 in 108 in
Experiment No. 1, shews the difference of friction between an ordinary
road, with flat top rails, and a newly laid road, in good condition,
with a round top rail.
No. 4.—EXPERIMENT made on the Friction of Tubs at Black Boy Colliery,
24th March, 1855.
A piece of road was selected, where the inclination was such, that the
tubs just run of themselves, having a fall of 1 foot 10 inches in a
distance of 50 yards. An empty tub set in motion, continued its motion
down the plane, which it traversed in 28 seconds, or at the rate of
about 3f miles per hour. The resistance thus shewn would be equal to the
fa part of the weight.
Diameter of wheel, 10 inches, ) .. 9Wl1 „ axle,
1*375 inches, J ratl0> * ^ ' l
On another plane of one in eighty, the tubs run down at about the same
velocity.
In the above experiment the gravitation of fa caused the tubs to
describe a space of 50 yards in 28 seconds, which is the measure of
friction.
No. 5.—EXPERIMENT on the Friction of Tubs at Xillingwortk Colliery, 3rd
April, 1855.
The same process was adopted in this experiment as in the preceding, A
piece of road was selected where the tubs just continued in motion when
moved from a quiescent state, and the following was the result, road in
good ordinary state :—
Length of plane, 93*5 yards. Descent, 3*42 feet,
the ratio of inclination being 1 in 82, which is assumed as the measure
of friction.
Diameter of wheels, 11*5 inches, | ,. ~,nr, . , axles 1*5
inches, 5 iatl0> ' U0 * l'
254
No. §.—EXPERIMENT on the Friction of Tubs at Andrew
House Colliery, March, 1855.
This experiment was conducted in the same manner as the previous
experiments. The road was in good ordinary condition, with flat top
rails, when it was found that at an inclination of 1 in 73 the tubs when
put in motion continued without any acceleration of velocity, making'
the friction the TV of the weight.
Diameter of wheels. 10'25 inches, ) ,. -, K . ,n „
axles, 1-375 inches, ) ratl0> ( ° ' 1#
No. 7.—EXPERIMENT on the Friction of Tubs at Crook Bank Colliery, March,
1855. This experiment was made in the same manner, the inclination
selected was 1 in 80. The road was in good condition, round top rail.
The friction would appear therefore to be equal to the -^tli part of
the weight.
Diameter of wheel, 8 inches, ) .. 1 . n ¦,
axle, 1-375 inches, \ ratl0> l m 6 ^^
The previous experiments were made upon planes just equal to the
friction of the tubs, and when the motion was very little, if at all,
accelerated, hence the sine of the inclination of the plane gives the
friction of the tubs. The following experiment was made with great care
by Mr. Atkinson, upon planes, the rate of inclination of which produced
an accelerated motion, the usual theorem in such cases being used to
ascertain the friction.
No. 8.—EXPERIMENTS on the Friction of Underground Tubs or Wagons, at
Pontop Colliery, by Mr. J. J. Atkinson, March, 1855.
The tubs or wagons were allowed to start from a state of rest near the
bottom of an inclined plane, and the time occupied in their running a
distance of 239-91 feet, with a fall of 9-35 feet in that distance,
being an average gradient of 1 in 25*66, was ascertained by the
vibrations of a pendulum.
The experiments were made on three different occasions and days, and
were as follows:—
FIRST. SET OF EXPERIMENTS.
11st Tub, 29-33 Seconds.
„ L _, . ) 2nd " 26-29
Empty TiiW3rd «. 2882
(.4th " 27-56
(-1st Tub, 27-30 "
1 2nd " 25-53 "
Full Tubs. -J 3rd „ 27.30 it
(.4th " 25-53
THIRD SET OF EXPERIMENTS.
fist Tub, 27-5 Seconds.
Empty Tubs.] ^ " j*J »
(.4th " 27-6 "
(- 1st Tub, 26-0 "
- „ ™ , ) 2nd " 27-5 "
Full Tubs. ^3rd „ 260
(.4th " 26-7 "
255
The second set of experiments were made by the Overman and back Overman.
SECOND SET OF EXPERIMENTS.
C 1st Tub, 27-3 Seconds. \ Average state of
Full Tubs. < 2nd " 26-3 " 5' lubrication.
(.3rd " 25-3 " Newly greased.
r 1st Tub, 28-3 " I Average state of
Empty Tubs. < 2nd " 31-4 " J lubrication.
(_ 3rd " 27-3 " Newly greased.
The following is the formula by which the friction of the tubs is
ascertained :—
Let d = the total length of the plane in feet, h = the total height of
the plane in feet, t = the time occupied in traversing the plane, in
seconds, g = a measure of the force of gravity in a vertical direction =
16 j-1^, being the number of feet through which that force
urges a body in the first second of time.
h Then — is the force of gravity resolved into the direction of the
plane,
being the sine of the angle of the inclination of the plane to the
horizon.
And from a well known theorem —— is the actual preponderating force
t g
urging the body down the plane, expressed in fractional parts of the
force
of gravity, when it is less than that force.
h d
And hence -^------=— is the force lost by frictional or other
resistances,
d t2g J
'
also expressed in terms of the force of gravity, by means of which
expression the results of the experiments have been calculated, as
embodied in the following table, which also exhibits the observed times
of descent.
256
Table of the result of EXPERIMENTS on the Friction of Coal Tubs on
Underground Railways, as tried in the Main Coal Seam at Pontop Colliery.
Friction or retarding- force in No. of Time
of terms of the entire force of
Experi- Load in the descending h
d ntM11,_
ments Tubs or the the plane gravity ss — — —-
±tr,i¥iAKJV.
and of contrary. in a
t2 S______
Tub. seconds.
------------------------------------
In Decimal notation In Vul. Fractions
1 Empty. 29-33 -02190001 u^„
The Tubs were not
2 Do. 26-29 -01765641
jg.J^ specially greased, but
3 Do. 28-82 -02128065
^.^ were supposed to be
4 Do. 27-56 -019G0035
^.m in their average state
5 Full of Coals. 27-30 -01922436 S5.iT7
of lubrication during-
6 Do. 25-53 -01635184
m\n the experiments.
7 Do. 27-30 -01922436
M-lm
8 Do. 25-53 -01635184
BT.jn
AVERAGES OF THE ABOVE EXPERIMENTS. 4 Empty.
-02010935 „Lg
4 Full. -01778810
^hf
8 Full & Empty. -01894872 T>^m
Diameter wheel, U35g | rati0jl:8.36
The above set of experiments were made upon rails having a flat top and
much worn, and the friction, though not more, perhaps, than the ordinary
underground roads in the district, being very considerable. A piece of
road was selected having round top rails, and where the road was in good
condition, and the following experiments were made for the purpose of
ascertaining the difference of resistance between the flat top rail,
with a road not particularly straight, or in first-rate condition; and
with round top rails, and the road straight and in good condition.
jy0m 9.—Account of EXPERIMENTS made at Pontop Colliery to ascertain the
Friction of Underground Tubs or Wagons, on the 9th and 13th April, 1855.
The tubs were allowed to start from a state of rest, and the time was
257
ascertained during which they traversed a distance of 147 feet with a
total fall of 3*83, being an average gradient of 1 in 38*38.
EMPTY TUBS.
No. of Experiments. Time in Seconds.
1 ...... 24
2 ...... 26
3 ...... 24
4 ...... 24
5 ...... 23
6 ...... 25
7 ...... 24
8 ...... 24
9 ...... 24
10 ...... 23
11 ...... 23i
12 ...... 24
13 ...... 26
14 ..... 24f
Averag-e . .. 24-2 seconds.
FULL TUBS.
No. of Experiments. Time in Seconds.
1 ...... 24
2 ...... 26
3 ...... 26
4 ...... 23
5 ...... 22
6 ...... 22
7 ...... 23
8 ...... 21
9 ...... 21
10 ...... 21
11 ...... 22
12 ...... 21
13 ...... 22
14 ...... 21
Averag-e .... 22-5 sees.
Now -j- — rs- = friction d t^g
and hence •^••T friction of empty tubs and -j^- friction of loaded tubs.
Nos. 8 and 9 Experiments being made with the same tubs, but upon
different descriptions of rails, and with roads in different states of
condition, shew the results to be greatly different. The average of the
empty tubs being respectively 4^-^27 and -gj-r> and of the loaded tubs
¦jtttt and rb-J tne general average being as s^W to rrrap shewing that
with proper rails, and with a straight road and in good condition the
friction or resistance is reduced fully one-half.
The following is the result of all these Experiments.
Ratio of
^T°- of
Diameter Diameter Diameter Ratio Experi-
NAME OF COLLIERY. of
of of Wheels of Friction ment.
Wheels. Axles,
to Diam'trto Weight.
of Axles.
Inches. Inches.
1 Hetton Colliery, Main Coal........ 11-5 1-3775
8-7 '1 l
2 Ditto, Minor Pit........ 11-5
1-3775 87 ;l fa
3 Ditto, Elemore.......... 7.5
1-3775 5-5 ;i Jj
4 Black Boy Colliery.............. io- 1-375
7-27:1 X
5 Killing-worth Colliery............ 11-5 1-4
s-21 ' 1 ]-
6 Andrew's House Colliery.......... 10-25 1-375
7-5 *1 J
7 Crook Bank Colliery.............. 8- 1-375
6- ' 1 ]
8 Pontop Colliery, No. 1........... 11-5 1-375
g-7 ;l ^
9 Ditto, No. 2........... n-5
1-375 8-7 ;l ni.35
258
We thus see that with 11 \ inch wheels, and with the road in good
condition, and round top rails, the friction is about the T^th part of
the weight, while with rails worn on the top or flat .top rails, and
with the road in ordinary condition, the friction is about the -^nd pare
of the weight. The difference arising entirely from the state of the
road and the rails, indeed this is plainly seen by the sinuous motion of
the carriages on roads in bad condition, and consequently the rubbing of
the flanches of the wheels against the rails being very great. The
result of wheels of 7 J inches in diameter, the friction on the ordinary
roads is about equal to the •^rd of the weight.
These are very startling results as regards the economy of the
conveyance of coals underground, and which raises the very important
question whether sufficient attention has been paid to the construction
of the carriages, of their wheels, and of the roads whereon they have to
travel. And it likewise points out, with undeniable force, the
imperative necessity of considering with all the energies in our power,
whether any, and what improvements can be made to diminish the
resistance. Such a desideratum being the foundation of all economy in
the transit of the coal from the workings to the shaft.
No doubt the height of the beds of coal, to a great extent if not
wholly, determines the height of the wheels to be used; but,
notwithstanding, we see that much may be done by a careful attention to
the form of the wheels and rails, and to the condition of the roads.
These experiments agree to a considerable extent with the experiments
made on the wagons at bank, hereinbefore alluded to, taking into
consideration the difference in the diameter of the wheels and axles.
These experiments give the resistance as equal to the -j^th part of the
weight, in carriages of ordinary construction. The resistance of the
wheels on the rails being equal to the -x^V~otn Par^ °^ ^e weight;
leaving the friction on the axle equal to the ^-^th part of the weight.
Thus :—
The resistance of the wheels on the rail being in the inverse ratio of
the diameter of the wheels, and the friction on the axles being in the
inverse ratio of the diameter of the wheels to that of the axle, we
have, as regards the wheels, the ratio of 3 : 1, and as regards the
friction on the axles, the wheels 3 feet diameter, and axles 3 inches in
diameter, or the ratio of 12 : 1, to be compared with wheels of 12
inches diameter, and axles 1J inches diameter, or the ratio of 8 : 1.
Then:—
CtoVt x f) + GIt x V2) =u^th part of the weight for the underground
carriages with wheels of 12 inches and axles 1| inches; which does not
differ materially from the result of the experiments.
259
In the case of the experiment of Black Boy Colliery where the tubs and
rails were in good condition, the ratio of the wheels and axles
being-7~27 : 1, the wheels being 10 inches in diameter:—we have
(toW X -f!) + (yfrj X T^ = ^th part of the weight; experiment, giving
the -gVnd part of the weight.
And again, in the case of the small wheels in the third experiment, the
wheels being 8 inches in diameter when new, or 7\ inches in iise:—we
have (-rata X H) + (tJt x H) = -aVtu; experiment showing the 3Vrd part
of the weight. The increased resistance in this case, no doubt arising
from the additional comparative resistance by the rubbing* of the small
wheels against the rails.
We may, therefore, I think, conclude that with wheels of 12 inches in
diameter, and of axles 1| inches, or with a ratio of 8 : 1 the friction
on the ordinary railways underground is equal to the ^g-nd part of the
weight ; but that with well constructed roads, wheels and carriages, the
friction may be reduced to the x^th part of the weight; and that with
wheels of 8 inches in diameter, the ratio of the diameter of wheels and
axles being 6:1, the friction on ordinary roads will be equal to the
-z^nd ; and on well-constructed roads, and proper wheels and carriages,
the resistance may be reduced to the ^th part of the weight; and so in
proportion to any other size of wheels. Since writing the above, Mr.
Sinclair, late Secretary to the Institution, and now Mining' Engineer to
the Tredeg'ar Coal and Iron Works in South Wales, has forwarded to me
some experiments which he has made on the friction of the trams used at
those works.
He says, a with a tram, the wheels of which were such as could be either
used on a tram-road or edge rail, 15 inches diameter, I found on the
edge rail it required ah inclination of 1 in 70 to move the empty tram
weighing 960 lbs.; and an inclination of 1 in 59 to move the loaded tram
weighing 3360 lbs."
Also, " I tried the following experiment. I had the way laid down
perfectly level, and placed a pully at the end; I then attached the tram
to a string, which went over the pully; and I found it required a weight
of 121bs. to move the empty tram of 960Ebs., or -J^-th. part of its
weight; and 32B5s'. to move the loaded tram of 2160Ibs., or ^-th part;
and 52ft>s. to move the tram when weighing 33601bs., or ^th part of its
weight."
Mr. Sinclair subsequently made the following experiments. Wheel 15
inches diameter, on edge rail. Empty tram 1226Ibs., 15Bbs. or ^V1^;
loaded with 1200B)s., making 2126Sbs., 32J3s. or TVth; and loaded with
2100Ibs.., making 3626Ibs., 51fbs. or Tlrst part of the weight. Vol.
III.—April, 1855. m m
260
And on Tram plate, diameter of wheels 19 inches, empty tram 880Ebs.,
92*. or gLth; loaded with 12001bs., making- 20801bs., 261bs. or ^thj and
loaded with 21001bs., making* 32301bs., 47Bbs. or 7^th of its weight.
These wheels are loose on the axle, and the axles also turn round. In
all these experiments the wheels and axles were well cleaned and oiled.
MOTIVE POWER USED ON UNDERGROUND RAILWAYS.
It need scarcely be stated that locomotive engines cannot be employed to
travel upon the railways underground. It has been previously stated that
the average height of the coal beds, at least in the counties of
Northumberland and Durham, is not more than four feet. It is true in
Staffordshire there is a bed of coal, or rather a series of beds, in one
mass of about thirty feet in height, but besides the question of height
there are other insuperable difficulties in the way of using locomotive
engines underground, viz., the effect of the heat and steam on the
passages or air-courses, and on ventilation of the mine, and likewise on
the health of the miners employed thez'ein.
We are thus precluded from the use of the best and most economical power
for the conveyance of the coals underground, and at present the
conveyance is confined to Boys, Ponies, Horses, Gravity or Self-acting
Planes, and Fixed Steam Engines. The Boys and Ponies being employed in
bringing out the coals from the face of the workings to the main roads,
—Horses on the level or nearly level parts of the main road,—Self-acting
Planes where the inclination of the beds of coal is such that the
gravitating power of the loaded tubs or carriages, is such as to
overcome their friction, the friction of the empty tabs, their gravity,
and the friction and gravity of the rope and sheaves on which the rope
runs,1—and Fixed Steam Engines used for dragging the coals up from the
deep workings, and more recently along the level, or undulating roads
where horses were formerly exclusively used.
BOYS AND PONIES.
Taking each of these in rotation, I have stated that boys are employed
261
to convey the coals from the workings of the mine to the main roads, a
distance generally of from one to two hundred yards, where, from the
height of the bed of coal, and from the intricacies of the workings,
horses cannot beneficially be employed. Generally, and until within the
last few years, bo}rs alone were employed, taking' one tub containing
from six to nine cwts. of coal at a time, and conveying from forty to
fifty tubs per day, and thus travelling from eight to ten miles per day.
Latterly, or within the last few years, small ponies have been used to
drag- the tubs, smaller boys being employed to drive the ponies, which
are generally three feet six inches to four feet in height, and thus the
coals are conveyed from the workings to the main roads.
Where the inclination of the beds of coal is moderate, the boys, or
ponies, convey the coals from the workings with great ease, but where
the inclination is considerable it is a more difficult undertaking, the
coals cannot be brought out of the dip workings without the use of
strong ponies or horses; and the operation of bringing the coals from
the rise workings on a steep inclination is very difficult, first, in
preventing the trams or carriages from over-running the boys, or ponies,
and next in the power required to convey the empty tubs up the plane.
An apparatus, on the principle of a self-acting* plane, has been in use
at the Killing-worth Colliery, introduced by Mr. John Liddell, which has
answered the purpose very well, when the inclination is about 1 in 3 or
4.
Figs. 1 and 2, plate II, shews this apparatus. A prop is placed near
the face of the working, to which is fastened the sheave B, the other
end being steadied by the short prop cut into the floor of the mine.
A counter-balance carriage W is made to run up and down a narrow
railway, two feet in width, on one side of the bord, the rope from which
is passed round the sheave, as shewn in the drawings, the other end of
the rope being* attached to the tub D. The counter-balance carriage
is loaded so that the gravity assists in dragging the empty tubs up the
plane, and this drag prevents the loaded trams from over-running* the
boys or ponies in their descent to the main roads. The prop A and the
apparatus is removed forward every night as the coal is excavated, so
that the trams are brought close to the face of the working, and this is
done with very little trouble and expense. The counter-balance
carriage rests against the prop E when at the bottom of the plane near
the main levels, and it passes into the depression F when at the top, so
that no brake is required to cause it to remain at rest when not in
action. By this apparatus large quan-
262
titles of coals are brought down from the workings at the inclination
above stated, of 1 in 3 or 4, with almost the same power as upon a level
road.
HORSES.
It has already heen explained that horses have been generally used on
the main roads, or water levels, or on roads not materially varying
therefrom. The comparatively small power which a horse is capable of
exerting renders it impracticable, consistently with economy, to employ
horses upon inclined roads where the gravitation of either the empty or
loaded tubs present any considerable amount of resistance.
It becomes, therefore, of importance to ascertain, on what inclination
of road, under all the circumstances which can arise underground, horses
can perform a maximum effect; so that in practice we may endeavour to
, lay out the roads to that rate of inclination; and to avoid deviation
therefrom as much as practicable.
The rate of inclination at which water will flow in a mine, subjected to
the casual interruptions incident to such cases, is about 1 in 260, or
about an eighth of an inch in a yard. This may, therefore, be said to be
the ruling gradient of horse roads generally, the water levels, as
previously stated, being generally used as horse roads. We have found
the friction of the tubs to be equal to the ^th part of their weight in
one case, and about the ^th part in another case.
In almost all the cases in underground traffic the load is entirely in
one direction towards the bottom of the pit; the empty carriages being
the only resistance in the opposite direction to the workings. And we
may take generally the empty tubs to be equal to 3 cwt., and the weight
of coals 9 cwt., making the weight leaded 12 cwt., and empty 3 cwt.
The inclination of road which will make the resistance equal in both
directions, supposing the friction to be equal to the -^th part of the
weight, will, therefore, be -g = 4 and-j^ = j^ and ^m x -^
= —— the inclination when the resistance is the same in both directions.
loo
And if the friction is equal to the ^th part of the weight, then
_, _„_ x 7J7T = ^rTTxr the inclination of the road, l-ooo 60
100
In the experiments on the power of horses dragging carriages on
railroads above ground, I arrived at the conclusion that a horse was
capable
263
of exerting a force of 120 lbs., travelling at the rate of 2 to 3 miles
an hour, and that he was capable of continuing that exertion for 10
hours, or for 20 miles in each day, when the load and resistance was
equal in both directions -, or that he was capable of exerting a force
equal to 180 lbs. in one direction, and 60 lbs. in the other, when the
load was in one direction only, and when the stages were not long,
performing, in the latter case, also 20 miles per day.
If the ratio of the weight of the loaded to the empty carriages be as 3
: 1, we have the inclination to cause the resistance to be the same in
both directions; the friction being equal to the ¥J^th part of the
weight
g__ j 2 1
o ¦ i x onn == Jnn the inclination of the plane.
The weight, therefore, which a horse would drag on a level road,
exerting a force of 1201bs in both directions, would be 120 x 200 =
240001bs. or 10 tons for 20 miles, or a gross performance of 200 tons
one mile per day; and of useful performance frds or 6f tons per 20
miles, or 133^ tons one mile, which may be termed the maximum practical
performance.
•
If the load is only in one direction and level, and a horse exerts
1801bs. with the load, and 601bs. with the empty carriages, then the
useful performance will be 10 tons conveyed 10 miles per day, or 100
tons conveyed one mile; but, if the inclination of the road is such as
to make the load equal in both directions, or 1 in 400, then a maximum
effect will be produced, and the useful performance will be 333|- tons
conveyed one mile.
I shall now give some cases of the performances of horses employed in
the conveyance of coals underground: —
1.—HETTON COLLIERY, ELEMORE PIT.
Weight of empty tubs 4 cwts. each. „ loaded tubs 12|- cwts.
each.
Chains. Chains.
Chains.
1st stage, 31 x 2 = 62 x 9 trips per day = 558 2nd do. 53 x
2 = 106 x 9 do. = 954
3rd do. 70 x 2 = 140 x 17 do. = 2380
4th do. 47x2= 94 x 18 do. = 1692
Total distance travelled ............5584
204
5584 Seven horses were employed, therefore -t=- = 800 chains nearly, or
equal to ten miles per day each horse. The load of each horse was
fourteen tubs of 12^ cwt. each loaded, and 4 cwt. each empty. Supposing
the inclination of the road such as that the resistance was equal in
both directions, and that the friction was equal to the ^th part of the
weight, the wheels being- 12 inches in diameter, the resistance would be
1621bs. for ten miles a day, or a performance of l,620Ibs, moved one
mile in a day j and the useful performance 5 tons 19 cwt. conveyed five
miles per day, or 29*75 tons conveyed one mile per day.
In this experiment the horses had to go to several stations, which
caused great delays, and consequently the distance travelled was very
small, though the resistance was more than ordinary. This was a single
line with sidings.
HETTON COLLIERY, ELEMORE PIT.
This was a piece of road of 1,280 yards in length, to one station only,
and the road was double. In this case the horses took 14 tubs, of the
same weight as the former experiment. There were 8 horses employed, and
they performed 99 journeys, which is equal to 17'22 miles per day for
each horse, with an uniform resistance of 162Jbs., and is equal to a
performance of 2,7891bs., moved one mile each day, the useful
performance being 5 tons 19 cwts., conveyed 8-61 miles per day, or 51*23
tons conveyed one mile per day. The horses were very powerful, and the
road was kept in excellent order, therefore the resistance was probably
less than the estimated amount of friction. This now forms the engine
plane of the Elemore Colliery, shewn in figs. 3 and 4, plate I.
HETTON COLLIERY, MINOR PIT.
This is a stage of 990 yards in length, on which seven horses were
employed, performing 100 journeys per day, the number of tubs taken at a
time being 9,, of 4 cwt., empty, and 12J cwt., loaded. These tubs have
8-inch wheels, the friction being about the ^th part of the weight. The
performance, therefore, is an average effect of 138-61bs., moved sixteen
miles a day, or 2217-61bs., moved one mile per day, and the useful
performance 3-825 tons conveyed eight miles a day, or 30-6 tons conveyed
one mile per day.
265
ANDREWS HOUSE COLLIERY.
This experiment was made at the end of the engine plane, shewn in Fig.
8, Plate I. One horse dragged 11 loaded tubs out, taking the same number
back again empty. The weight of the loaded tubs was 144 cwts. 1 qr. 21
lbs., and of the empty tubs 58 cwts. 1 qr. 21 lbs. The inclination of
the road was 1 in 122, descending- in the direction of the load. The
number of journeys each day was 57 for one horse, and the distance being
285 yards, consequently the total distance travelled was nearly fifteen
miles per day, friction of tubs ^rd part of their weigdit.
Cwts. Qr. ffis. ills.
IBs.
Then 144 1 25 x ^ = 73 gravity,) - .t .
, ,
i ™-, r. . ? = 148 resistance, loaded.
x ^ = 221 friction, )
And 58 1 21 x -Hr*- = 30 gravity,) „_!-
, _rt ° . > = 120 resistance, empty.
X TV = 90 friction, ) r J
Mean resistance 1341bs., moved fifteen miles per day, which is equal to
2,0101bs.; moved one mile per day; and the useful performance is 7*22
tons, conveyed 7'5 miles per day, or 54-15 tons conveyed one mile for
such horse. It must be remarked, however, that this was under very
favorable circumstances, as the horse was not detained at each end, ami
the gradient was about 1 in 100.
MARLEY HILL COLLIERY.
At this Colliery there are four stages, viz.:—
Chains. Trips. Chains.
Gibside, 69-7 x 34 = 2369-8
Crosscut, 105-5 x 24 = 2532-0
Central, 108-0 x 22 = 2376-0-
No. 9, 100-5 x 22 = 2211-0
Total distance travelled . .. 9488-8
9488-8 Fifteen horses are employed, therefore '¦-.,-." = 632 chains,
or 7-9
miles x 2 = 15*8 miles per day each horse. The number of tubs taken at a
time was 10; the loaded tubs 13 cwt., and the empty tubs 5 cwt.,
consequently the useful performance was 7'9 miles x 4* tons = 31*6 tons
conveyed one mile per day j the load being all in one direction.
266
SPRINGWELL COLLIERY.
These are two cases where, besides conveying the coals along the stages,
the horses in the first case have to drag the trams from the top of the
engine plane to the shaft, a short level stage of 100 yards only; and
also to take the trams from another flat to the shaft, the stage being
560 yards, and the inclination against the load 1 in 80, which is a very
disadvantageous application of horse power. And in the second case, the
horses take the trams from a pony flat to the landing, where the engine
drags them along a stage of only 572 yards, and the horses have also to
drag the empty engine set into the landing. Three horses are employed in
the first case, the number of journeys per day being 63 on the 100 yard
stage, and 15 on the 560 yard stage. The load in both cases is eight
tubs, the weight of the empty tubs being 3^ cwt., and when loaded 11|
cwts. These tubs have 10-inch wheels. Supposing the friction to be equal
to the -^th part of the weight, then the resistance, with the load, up
the stage of 572 yards, will be 2321bs., and on the level 1161bs, the
relative distances travelled being 8,580 and 6,300 yards, the mean
resistance will be 183'51bs., which is the maximum practical performance
of a horse above ground. The useful performance by the short stages, and
delays at the termini, being only 3'9 tons, conveyed 2-8 miles, or 10-92
tons conveyed one mile for each horse.
On the stage of 572 yards, four horses are employed, the number of
journeys per day being 67, and the load 6 tubs, the road being
undulating but generally level, the weight of the tubs and coals the
same as in the last experiment. The useful performance in this case is
2-8 tons, conveyed 545 miles per day, or 15'26 tons conveyed one mile by
each horse.
The following table will shew the performances of horses under-ground in
these several cases, and also the performance of horses above-ground
with the ordinary coal wagons:—
267 TABLE OP THE PERFORMANCE OF HORSES UNDERGROUND.
Length XT . Dia- Weight of each
Average Tons
N-nmher of Number mcter
Irani. No. of performance of conveyed
IOCALITIFS of Horse °f of
Inclination----------------------Trams each Horse by e/ch
LOOAUriLS. ot Koadg_ Trips wheejs. ol:
Horse Loaded. Empty. "» per Day. Horse, On,
'-----------Per-----------¦Koaa'----------------------ff?"
---------------------- Mile per
Yards. y" Inches. Cwts. Cwts.
lrlp" Tons. Miles. Day.
r 682 9~]
J 1166 9
Elemore Colliery.....i 7 < > 12- 1 in
130 12-5 4- 14 5-95 5- 29-75
f 1540 17 {
{ 1067 18 J
Ditto ...... 8 1280 99 12- 1 in
202 12-5 4- 14 595 8'61 51-23
Hetton Colliery.*........ 7 990 100 8- 1 in
130 125 4- 9 3-825 8- 30-6
Andrew's House Colliery 1 285 57 10-25 1 in 222
13-013 5-3 11 7"S2 7-5 54-15
Marley Hill Colliery.... 15 2046 102 10- 1 in 144
13- 5- 7-9 4- 31-6
( 100 63 10- Level. 1 ( 8
Spring-well Colliery .... 3 {
> 1L5 3-5 I 3-9 2-8 10-92
{ SCO 15 10- 1 in 80j {15
Ditto .... 4 572 67 10- Level.
11-5 3-5 C 2-8 5-45 15-26
( 1 1760 10 36- Level. 75- 25-
6 10- 10- 100-
Above ground ......{
I 1 1760 10 36- 1 in 400 75- 25.
8 13-33 10- 133-33
It will be seen from the foregoing table that the generally useful
performance of a horse under-ground is not more than one-third of the
ordinary, or one-fourth of the maximum useful performance of a horse on
the colliery railways on the surface. The second case of Elemore
Colliery is an exception, the performance there amounting to one-half,
but this case was a peculiar one, the road was in excellent condition,
it was double from end to end of the stage, and there was not,
consequently, those stoppages at the passing places and at the ends of
the stage which so materially diminish the useful performance of a horse
under-ground. The horses employed on this work were powerful ones, and
required great feeding to keep them in good working condition j and the
same is the case at Andrew's House Colliery.
I shall now give the performances of horses employed under-ground on the
tram-roads in South Wales, which I have been favoured with by some of
the managers of the extensive coal and ironworks in that district of the
country.
The following table is an abstract of the performances of horses in 61
coal and iron-stone levels, which I have compiled into the same form as
that of the performances of horses in the County of Durham. Vol.
III.—April, 1855. n n
268
T3 — V -
*» £."§ £3 S" csocovocseoio
cSjSgQ o <-i i- 10 -# (m co
O :> »> O ^^ iH S>- O O
CO O 00
B C ^.HJ ga © O CQ -H
-* CO t~
XJ1 V O * i-l rH
rH rH rl i-H i-l
rH <g —" . K
Ol OJ 55 PZ
1_3 <u«) $ -*
-* 00 O CM CO
^~j fflog^ a >p "tf -*
CO 00 CM ©
^ «§£5 8 <» cb cb o cb
cb cm
r>» s dffiH
—i------—------—--------------------------------------------------------
-
& ££.«*, • -* «>- co c©
OS «
^"gSp- | op r* oo io oo cm <»
H 8.° H cm cb cb cb cb
»o as
^ o if <j w
O <~ fl J » rH^^COt-OOcb
03 °l ~*—;—S—----------------------------
'-'[J ^W CO CO CM CO CM CM <M
CT * u^ 8 ¦« B. CO 00 t^ !>- Cft
b S|di-SS-& . . <¦? .n oo cm co
»^ <! KH "^ CO CO TH CO CO 10 J>-
H-, -------------.-----------------------------------
<—> » © © CM CM CM © ©
" .SO -J -# ^ © T*l ^* T* -#
Q -grt S co co © tj<
•** co co
£~! <B <N <M
•-« —' r-i CM CM
L> S fe .s : : : : : :
XT! ________________^ MrHrH^^t^^
^G -S "S "s s "S © r- A< oo
o> b- £-
P5 PS°g § CM r- CM
i-l rH ,-. ,-.
o ____^ ^___________________
td S)"h Jf- v >>
CO lO
' 5s ° a. *¦< S ,5 CO
i-l OJ CO t-
rv, S o'E p,00 ^ Mi CO
00 C2 CM ©
U 5^^ W« cb cb ¦# cb cb cb
cb
hh £ c.S •§ r-i o • i-i
ift • •
< Za "1------------------------------*---------------
3 "So a (dc^ ocotMococieo
Ul s=o.2 9 b o o w >o oj
i-h o
^S^^liS r-!00r-<^t-
p1 <D
W__________________________________________________________________
pr. SO
---------;--------------------------------------------------------------
-----------------------------------------
rv3 2 gi «s t^t^C5-<*icoioo
•-^ ? -isS?12 oc-tcocoocooo
h i i? s a ooio-Ho<Mco-tf
^ ^ 1^3 1« rHrHrH
rlr-l
Ph
------------------------------------------------------------------------
--------------------------------
pH a<MP lO i-H
CO Ci CO t^. CO
,, g°S COt^-*C0r-lCM(M
£-----s^3----------------------u----------__
p :::::::
S o .......
o « :::::::
pq o : % ; : i : ' •a
^ m : S : : : : 2
(T\ O t3 J«
^ tJ ^J tj ^
O § &B § § §
S 6C
m t, ia fci k ti >h
s
The above table is a most important contribution to our information of
the performances of horses in the South Wales District, and exhibits,
very conclusively, the necessity of improvements in the economy in the
conveyance of the coals and minerals under-ground in that part of the
country.
269
It is necessary to explain, however, that, as will be seen on
examining-the table, the reason for such a diminished performance is not
so much from the small load which is taken at a time, as from the short
average distances which the horses travel; and this is owing', in a
great degree, to the practice in that country of taking the trams into
the working-places with the same horses which take them along- the
levels, by which great delay of time is occasioned; and also from all
the levels being-single, with passing places, not very frequent, and
which is likewise the cause of considerable waste of time, so that the
average distance which a horse travels in each day is little more than
6| miles.
There is no doubt that the state of the levels, and of the trams also,
contribute to produce this low standard of performance. The levels
are mostly those which have been driven for the drainag-e of the mines,
and as before remarked, are extremely crooked and tortuous, following
all the sinuous undulations of the inclination of the strata, and are
mostly tram-roads, and very liable, from the water in the levels, and
from occasional falls from the roof and sides, to be not in good
condition. The trams are not, likewise, well constructed, the wheels
are almost generally loose on the axles, and there is not much pains
taken in fitting them up. The more recently made roads are in better
condition, and the trams are fitted up with more care, so that there is
no doubt a more favouralla result will shortly be accomplished. Still
the performances of the horses, and consequently the vexy great cost in
the conveyance of the coals and minerals in this district, demand that
every investigation of which the subject is capable, is incumbent on the
Mining Engineers of the present day, and which it is trusted this
inquiry may be the means of promoting. There does not seem, at first
sight, by these tables, so great a benefit from the adoption of the edge
rail, as will appear from a short investigation. Taking the two first
cases, the difference is about ten per cent., but the wheels of the
trams are 20| inches, whereas the wheels of the edge rail trams are only
17 inches. In the last two cases, where the wheels are the same
diameter, the difference is equal to fifty per cent. The performance
in the last case is quite equal, in respect of the load taken, to that
of the roads in Durham, except that in the latter cases the wheels are
from 8 to 12 inches, whereas in the former they are 17 inches in
diameter. But the falling off in the distance travelled is very
striking', and can only be attributed to the causes which I have pointed
out.
The general result, however, both in Durham and South Wales, points out
with irresistable force the great necessity, in an economical point of
270
view, of the substitution of machinery for horse labour, in the
conveyance of coals and minerals under-ground. For, if it has been
thought advisable almost, if not entirely, to supersede the use of horse
labour in the conveyance of minerals on the surface, where the
performance of a horse is so much greater than under-ground, how much
more then is it necessary for such a substitution under-ground, where
the performance of horses is so extremely deficient and their employment
so costly.
SELF-ACTING PLANES.
The next subject for consideration in the conveyance of coals undeiv
ground is the employment of self-acting planes, where the gravitation of
the loaded carriages or tubs is sufficient to overcome, 1. The friction
and gravitation of an equal number of empty carriages or tubs. 2. The
friction of the rope wheel, and sheaves, and the rope whereby the plane
is worked, and to leave a sufficient surplus of force to perform the
operation of letting down the loaded, and dragging up the empty
carriages in a given time.
This description of power is the cheapest of all power used in the
conveyance of coals underground, either animal or mechanical; and it is,
consequently, of the greatest importance to ascertain to what extent,
and under what circumstances it can be employed. It can only, of course,
be used when the coals have to be brought from a higher to a lower
level, and where the inclination is such as to produce the requisite
gravitating power, and hence it will be necessary to inquire at what
rate of inclination, and under what circumstances such a power can be
employed.
The theory of the action of self-acting planes is well understood. The
moving power G is the gravitation of the loaded carriages W, multiplied
into the Sine of inclination of the plane, consequently G = W Sin. I.
There is, then, opposed to this—the gravitation of the empty carriages g
= w Sin. I, w representing the weight of the empty carriages, added to
the friction of the loaded carriages F, the friction of the empty
carriages f, and the friction of the rope wheel, rope and sheaves on the
plane n, consequently, when G = g-fF + f+n, the moving power is equal to
and balanced by the resistance. There is, then, a further balance of
power required to overcome the vis inertia of the whole mass, and to
cause the carriages to perform the descent and ascent of the plane in a
given time. Let S = the space to be traversed or the length of the
plane, r = 16^j feet, the space which a falling body descends in a
second of time, and t the time of descent, and w' the weight of the rope
wheel, rope
271
and sheaves on the plane. Then, according to the well known law of
falling bodies, -^-------------—-———¦— = the force required to cause the
i* t
trains to pass down and up the plane in the time t, which make G'. We
have then G = the moving power opposed to g + F + f + n in all cases. If
we, therefore, make F' = g -f F + f + n, we shall simplify the notation,
and retaining G' = the gravitating* or surplus power requisite to cause
the trains to traverse the space S in the time t.
Hence G> = G - F = (W + w + wQ x S
rt3 v '
G — F
likewise t= TWWpIK! (3)
N G — F x r v J
and Sin. I = ------------------------------------------------- (a\
W - w W
I shall now give some examples in practice of cases where the
inclination is the least which can be employed for this description of
power. Where the inclination is considerable, or where it is such as
always to produce a surplus power in G;, more than sufficient to cause
the trains to traverse the space S in the time t, then no theoretical
rules are necessary the time t can always be regulated by the number of
full and empty carriages -, and recourse can be had to the brake if
these cannot be so regulated as to produce the required speed, but upon
the flat planes some calculations are necessary.
The following experiments were made on a plane of a very moderate
inclination in the Elemore Pit, Hetton Colliery:—
The plane is, exclusive of the landings at top and bottom, 1565T feet in
length, with an entire fall of 47 feet, or an average inclination of 1
in 33"3. It is perfectly straight, but not of an uniform inclination,
having an increased inclination at the top, to put the trains into the
requisite velocity, and is gradually diminished towards the bottom of
the plane; which by producing an increased resistance to the empty
carriages
272
at the top, and a diminished gravitation of the loaded ones near the
bottom brings the trains to rest.
A section and plan of this plane is given in Plate I, Figs. 3 and 4, and
the following are the experiments made, a portion of 389 yards in length
being selected for the experiments, with a fall of 38*77 feet, or an
inclination of 1 in 30.
EXPERIMENTS made on the Polka Inclined Plane, Elemore Colliery, March
\<Uh, 1855.
No. No of N*°-of WEIGHTS. Length Height
Descent
of full enlp" T ., , „ '. Time. of
of per OBSERVATIONS.
ESP.Tub,TtL ^r i ssr
lbs. lbs. min.sec. feet. feet. inches.
1 24 26 34-310 12-038 2-45 1167 38-69 1-2
Diameter of Wheels,
2 24 26 34-502 12-038 1-55 1167 38-69 1-2
12 Inches
3 24 26 34-406 12-038 2-0 1167 38-69 1-2
^^ rf ^
4 24 26 34-406 12-038 2-11 1167 3869 1-2
1.3775 Inches.
5 24 26 34-406 12-038 2-2 1167 38-69 1-2
Inclination of
6 24 26 34-406 12-038 2-58 1167 38-69 1-2
^ * 8°"
7 24 28 34-406 12-964 3-20 1167 38-69 1-2
l"V2r3°4N5°6} 34'406 12'038 2"18 1167 38"69 1>2
The result of these 6 experiments, with 24 loaded and 26 empty tubs, is
as follows:—The time of descent averaged 2 minutes 18 seconds; the
weight of the descending load was 34*406 lbs., and the weight of the
ascending load 12*038 lbs. The inclination of the plane was 1 in 30. We
have, therefore, the gravity of the load or moving power G = 1146*8
lbs., and the gravity of the ascending load g = 401*3 lbs. The tubs had
wheels of 12 inches diameter, and axles 1*3775 inches in diameter, and
the road being in good condition with round top-rails, we may,
therefore, assume the friction to be the same as that of similar wheels,
tubs, and railway, as shown in the experiments in the main coal seam,
viz.:—r^th
-
273
part of the weight. This would make the friction of the loaded tubs ¥
= 318*6 lbs, and the empty tubs f = 104 lbs. We have then
(W + w + w')xS (34*406 +12*308 + 3453) x 1167 ,„, „„
----------F?----------*-------------10& x 138*-------------= -WWMfr-
= G' the force to cause the trains to traverse the space S in the time
t. And, therefore, 1146-318*6 + 104 + 401*3 + 191*15 as 131*75 lbs. the
friction of the rope, rope-wheel and sheaves. The weight of the rope
being 825 lbs., the rope-wheel 1120 lbs., and 2 of the sheaves in action
at a time 1508 lbs. = 3453 lbs., consequently, the friction is equal to
the •j^.^-th part of the weight.
Another experiment was made upon this plane, as will be seen in the
table, with 24 loaded and 28 empty tubs. The result of which was that
the sets were run in 3 minutes 20 seconds. This gives
(Wj^+wO^s = 92.68 IU G,
r t8 and, consequently,
1146*8 - 318*6 + 142*86 + 401*3 + 92*68 as 191*36 lbs., the friction of
the rope, &c. The velocity of the carriages being* much less than in the
other experiments, and a difference in the greasing of the wheels of the
tubs may account for the difference between this result and the former.
The number of tubs which are usually run down at a time in regular
working- is 24 loaded and 24 empty. The time of running being about 2
minutes. It will be seen, however, that in case of need, an additional
number of tubs can be taken up, or a return load equal to the gravity
and friction of 4 tubs, or a resistance equal to 77*72 lbs. The regular
day's work of 12 hours is about 70 trips.
Taking the result of the first 6 experiments, and the every day's
experience of the working of this self-acting plane, we may safely
assume that such a power can be employed in the conveyance of coals
underground at an inclination of one in thirty, with a speed of between
7 and 8 miles per hour j and that with 24 tubs, there is an excess of
power equal to about -j-^-th part of the moving power, upon a plane
about a quarter of a mile in length.
274
The following experiments were made at my request on an inclined plane
at Pontop Colliery, by Mr. Atkinson, a plan and section of such plane
being- sliown in figs. 5 and 6, plate I.
A space was marked out on the plane, the length being 1217 '4 feet= S,
the descent being 44*08 feet, making an inclination ofl in 27*62.
Thirteen loaded tubs were run against 13 empty tubs, and the following
was the time of descent of seven sets of experiments:—>
Yiz. ...... 1 ......205 seconds
2...... 176 „
3 ...... 204 „
4...... 195 „
5 ...... 180 „
C...... 178 „
6...... 175 „
Average time 188 seconds, nearly.
The weight of the loaded tubs is 19'6951bs. = W, and the empty tubs
7-514 lbs. =w. The rope-wheel 1110 lbs., the rope 1303 lbs., and the
sheaves 1145 lbs., together 3559 lbs. = w'. Consequently we have
19*695 7-514 19-695
G = ~@ = 71811*, g = zfQ2 = 272 lbs. F = -j~ = 157-51bs.,
7*514 and f == -qkTs- = 78-5 lbs. The friction of the tubs having
been ascertained by No. 9 set of experiments previously given.
We have then------------3—------= 65*12 lbs. G'
r r
And, consequently, 713 - 272 + 157-5 + 78-5 + 65-12 = 139*88 lbs. the
friction of the rope-wheel, rope, and sheaves, being about the l-23rd of
the weight.
Thirty-four runs is about the every day-work of this plane in twelve
hours—16 loaded and 16 empty tubs forming the train in each run.
The experiments on this plane corroborate those of the Hetton plane, and
also the conclusion arrived at, that, with the present tubs in use
underground self-acting planes can be used at an inclination of 1 in 30.
In this experiment the rate of speed was 1217 feet in 3 minutes and 8
seconds, which is at the rate of 5 miles per hour with 13 tubs only;
whereas 16 tubs is the usual number used, which is a power equal to 23
per cent, greater.
275
FIXED STEAM ENGINES. • 'The next description of motive power used in
the conveyance of coals Underground is the Fixed Steam Engine.
This description of motive power has been used for several years. More
than thirty years ago a series of engines were in use at Killingworth
Colliery—the first one was placed near the bottom of the pit, which
pumped water up a staple of twenty fathoms in depth, and the coals were
also drawn up from the same level to the bottom of the pit by an
inclined plane, a distance of about 500 yards.
On pursuing the workings further to the dip, another steam engine was,
subsequently, placed at the point from which the former engine dragged
the coals* and this second engine, which was erected at about 500 yards
from the bottom of the pit, dragged the coals from a further distance of
500 yards, and from an increased depth of level of twenty fathoms.
And lastly, on the prosecution of the workings still further to the dip,
a third engine was erected at the distance of 1000 yards, and at a level
of about forty fathoms below the bottom of the pit; which engine dragged
the coals a further distance of 500 yards, and at the increased depth of
about thirty fathoms:—making altogether a series of engine planes
drag'ging coals a distance of 1500 yards, and from a depth of level
about eighty fathoms below that of the bottom of the pit.
And it may be also stated, that the water was likewise pumped from this
extreme distance, and from the depth of eighty fathoms below that of the
bottom of the pit, by a system of sliding wooden spears, and pumps laid
down the drifts.
The boilers supplying the steam were placed at the stations where the
engines were placed, the smoke being conveyed to the bottom of the pit,
by drifts or flues prepared for that purpose.
With such an extensive application of engine power more than thirty
years ago, it is rather a matter of surprise that such a power has not
since that period been more extensively employed underground. There are
no doubt instances of the application of engine power at a great many
collieries in the trade, but these have, I believe, been almost
exclusively confined to a single engine placed near the bottom of the
pit, and drawing coals and water up a single plane from the deep
workings. Until recently, no attempt has been made at the introduction
or employment of the Yol. III.—April, 1855.
o o
276
steam engine underground, as a system of motive power in substitution of
horse labour.
We have already seen that horse power underground is employed at a great
disadvantage, as compared with the employment of horse power above
ground, the efficient performance in the former case not being more than
50 per cent, of the efficient performance in the latter. When it is
considered, therefore, that the principal cost of a steam engine is
fuel, and that this article is in superabundance at all collieries, and
that the fuel which is generally used by the steam engines at a
colliery, can be obtained at a comparatively small cost j it is a
subject of great importance how far the use of steam engines can, in an
economical point of view, be employed in substitution of horse labour in
the conveyance of coals underground. But it is likewise not of less
importance to ascertain, to what extent it can be employed, and in what
manner, in the conveyance of coals to the deep of the pits, and to a
greater distance from the shaft, than it is practicable to accomplish
economically by horses, and so likewise to supersede the cost of sinking
pits.
In the investigation of this important question, in the economy of the
conveyance of coals underground, I have obtained all the information in
my power, and have had such experiments made, at the different
collieries where engine power has been used, as will, I trust, enable me
to exhibit to the Institute such information as will enable them to
arrive at a correct practical conclusion on the subject.
The experiments embrace practical results in almost all the different
applications, requisite to establish a complete system of fixed engine
power in the transit or conveyance of coals underground, where it is
advisable to resort to the use of such a system j and which, together
with the aid of self-acting inclined planes; will present a system of
mechanical power, for the conveyance of coals underground in any
colliery, without the aid of horses, except as auxiliaries to those two
mechanical powers.
Firstly—I shall therefore, first of all, give experiments on the powers
and capabilities of fixed engines employed in dragging coals from the
dip, where the inclination of the strata is such, that the empty
carriages have sufficient gravitating power to drag the rope after them,
and which is to be used in dragging the loaded carriages up the plane.
This is the system already alluded to as having been practised in the
trade for several years. I shall give experiments on engines of this
description employed at Hetton, Killingworth, and Springwell collieries.
Secondly—I shall then give experiments on the powers and capabilities
277
of fixed engines used as substitutes for horse power along the level
roads. The roads rising from the shafts, or bottom of the pits, to where
the coals are to be brought from, and where hitherto horse power has
been almost exclusively used; and these experiments will extend up to
that inclination where the self-acting inclined plane comes into
operation, or where it can be used. This section will, therefore,
embrace the system of engine power conveyance, from a level or
undulating road to the rise, or above the level of the pit, until the
self-acting plane can be used.
Thirdly—I shall also give experiments on engines—practically the same,
however, as those last described—used, from the level of the pit to such
an inclination dipping from, or below the level of the pit, where such
inclination is not sufficient to enable the empty carriages to drag out
the rope, which is afterwards to be used by the engine in dragging the
loaded carriages up the plane:—forming a system of engine planes between
the water-level line to the dip, up to the point where engine power can
be employed with a single rope in dragging coals from the deep of the
mine, as in the first case;—and thus completing the system, in all the
varieties, of fixed engine power underground.
The experiments which I shall give in illustration of the two last cases
will be from engines actually employed at Killingworth, Hetton, Marley
Hill, and Black Boy collieries.
In the investigation of the powers and capabilities of underground
engines, the cases will comprise the application of engines, where the
cylinders or power is placed underground, and where the boilers
producing the steam is also placed underground. But it will likewise
comprise cases, where the cylinders or power is placed underground, and
where the boilers are placed on the surface, the steam being conveyed
down the pit in pipes; and it will also comprise cases, where both the
boilers and machinery are placed on the surface, and where the ropes
dragging the load are taken down the pit.
The following are the experiments alluded to:—
No. 1. Experiments on engines dragging coals from the dip with a sing-le
rope: Hetton, Killing-worth, and Springwell Collieries. No. 2.
Experiments on engines dragging coals along the level roads where horses
were formerly used : Hetton Colliery Elemore Engine Plane.
East Minor Plane, klllingwortii and marlky hlll collieries.
278
No. 3. Where the engine is employed in dragging coals along the level,
and likewise in a cross-cut direction, midway hetween the level and
the full dip, where the first description of engines are employed: Black
Boy Colliery. In the last case the engine is also employed in pumping
water from the dip by a process which will be hereafter described—an
operation which is very essential, if the extension of engine power is
to be applied to supersede the frequent sinking of pits. It was scarcely
necessary perhaps to give drawings of any engines, as there are a great
variety of forms of engines which may be used for the purpose. I
have, however, thought it advisable, for the information of those who
may not have had opportunities of seeing such description of engines in
operation, to give drawings of two different kinds of engines which are
actually at-work; and I shall endeavour to illustrate, with the aid of
those two drawings, the different applications of engine power requisite
to complete the system of fixed engine power to which I have previously
alluded.
Figs. I., II., and III., Plate III., are the Ground Plan, Front
Elevation, and End View of an underground engine which I have erected at
the Black Boy colliery, near Bishop Auckland. The engine is placed
underground, and the boilers on the surface; the steam from the boilers
being conveyed down the shaft or pit by cast iron pipes, and the exhaust
steam being also conveyed to bank up the pit in the same manner. The pit
is what is called a downcast shaft, namely, the air for the ventilation
of the mine being conveyed down the shaft.
The construction of the engine is, what is called a self-contained
engine, the whole of the machinery being placed upon bed plates,
rendering it capable of being readily removed from place to place, and
taking up as little space as possible, both of which are essential
requisites in such applications of power. Two cylinders are used, and
likewise a fly-wheel, steadiness of action being extremely desirable in
such cases, especially where wire ropes are used.
Two sets of rope rolls, AB, CD, are used in this case, all of which are
capable of being attached or detached in, or out of gear—to run freely
round upon the axles when the rope is dragged out from the engine, and
to be attached to the axles when the power of the engine is applied to
drag the train of tubs up, or along the plane. It is not necessary to
give any detailed description of the machinery, as this will be
sufficiently
279
comprehended from the drawings, and from the well-known mode of
construction of such engines.
Figs. X., XI., and XII., Plate I., show the ground plan, and sections of
the planes on which this engine is applied. One set of rolls, say C and
D, drags the loaded and empty carriages back and forwards on the plane
Fig. X., and sect. Fig. XI., suppose between the Howlish landing and the
landing near the pit; and the other set of rolls, A and B, drags them
along the plane Fig. X, and section Fig. XII., suppose between the
Wood-side plane landing and the pit. One roll of each set being
alternately thrown in, and out of gear, as the loaded trains are drawn
towards, and the empty trains from, the engine.
This operation is thus performed. Sheaves, a and b, are placed at the
ends of the planes, and besides the two ropes attached to the two rolls,
what is called a tail rope passes round these sheaves, namely, a rope of
the same length of the plane, one end of which is attached to the end of
the loaded train, when the train is at the end next the sheave; and the
other end is attached to the empty train at the landing near the shaft.
When the engine therefore drags the loaded set towards the shaft it
drags the tail-rope with it, and the other end being attached to the
empty train of the other roll, it also drag-s the empty train, and with
it the rope out from off the roll. When, therefore, the loaded train
arrives at the landing near the pit, the empty train arrives at the end
of the plane next the sheave. The gearing of the rolls is then changed,
and the same operation alternately goes on, throughout the day. This
arrangement requires a double line of railway, or three rails, with a
passing-place in the middle between the pit and the landings.
Sometimes, however, where a great quantity of coals is not required to
be conveyed, and a single line only is laid down (and this is the case
in this instance), the rope from one of the rolls leads along the middle
of the road, and is called the main rope, and the rope from the other
roll leads along the side of the road, and is called the tail rope; this
latter rope passes round the sheave at the end of the plane, and is
attached alternately to the end of the loaded and the end of the empty
set. Suppose the loaded set at the landing next the sheave, the main
rope is attached to the one end of the train, and the end of the tail
rope to the other—the train is then drawn to the landing next the shaft,
by which process it drags after it the tail rope from off the other
roll. The tail rope is then attached to the end of the empty set, and
the end of the main rope to the other; the main roll is thrown out of,
and the roll of the tail rope
280
into gear, and the empty set is thus drawn to the extreme end of the
plane, or to any of the intermediate landings, by the tail rope which
passes round the sheave.
Plate IV., Figs. I., II., and III., shows a Ground Plan, Front
Elevation, and End View of an engine with an endless rope; Fig. I. being
a ground plan, Fig. II. a front elevation, and Fig. III. an end view.
The construction of the engine itself is the same as in Plate III., with
two horizontal cylinders, and attached to a bed plate, but the
application of the rope rolls is entirely different—a, is the driving
pinion on the crank axle, which works into the cog wheel b; on the same
shaft, and fixed thereto, is a wheel c, with three grooves, as shown in
the drawing— and d, is a similar grooved wheel—g, is a horizontal
sheave, round which the rope passes, and which moves upon wheels, as
shown, and h, is a vertical sheave, over which a rope passes, one end of
which is attached to the framework of the moveable wheel g, and the
other to a heavy weight w, and at the end of the plane another
horizontal sheave is placed, round which the rope winds.
Figs. VII. and VIII., Plate I., shows the plan and section of the plane
which this engine works, and Fig. IX. shows the arrangement at and about
the pit where the engine is placed.
The mode of operation is as follows:—The rope is an endless one; it
passes three times round the grooved wheel c, worked by the engine, and
the same number of times round the grooved wheel d. The darts show the
direction which the rope runs. Passing along in the direction of the
dart 1, it passes over the upper side of the wheel c, in the groove 3,
to the underside, and over the groove 4, of the wheel d, then over and
under grooves 5, and 7, and under and over 6, and 8, and from the upper
side of 8, in the direction of the dart 9, around the sheave g, and so
along the plane in the direction of dart 2, to the sheave s, shown in
Fig. VII.,
Plate I.
The ropes always pass in the same direction, the loaded train being
attached to the rope, dart 1, and the empty train to the rope, dart 2.
It will therefore be seen that the action of the engine is always direct
with the rope 1, and the loaded train; and the rope is prevented surging
by passing round the three grooves on each of the wheels c, and d, and
from them around the stretching wheel g, which, being attached to the
weight w, keeps the rope always tight around the grooved wheels, and
along the plane.
281
FRICTION OF ROPES ON FIXED ENGINE PLANES.
It is necessary, before going into the elucidation of the power and
capabilities of fixed engines, to know the amount of friction of ropes
on fixed engine planes, especially when the empty tubs are to take the
rope down the plane, which rope is again to be used for dragging the
loaded tubs up the plane; as this determines the limits of the
employment of engines of the description of No. 1. And, as the
employment of a sheave at the bottom or end of the plane, with a tail or
endless rope, is attended with a good deal of friction; and,
consequently, requires a greater amount of steam power, it is necessary
to ascertain on what inclination of plane, and with what a number of
tubs the rope can be taken out from the engine.
The theory for fixed engine planes is the same as that for the
self-acting plane, except that there is no return set of tubs and rope
to drag up the plane. Retaining the same notation as heretofore, we
have
G' = G-FT-n = (W+ryX3(l)
w + w' v '
t= |(w + w')xs (3)
N G - F + n
(W + W') X S ______
—rp—+T+-*
And sin I = —--------------—— (4)
The following are some experiments made for the purpose of ascertaining
the amount of friction of the rope, rope wheel, and sheaves, or the
value of n.
282
No. 1.—EXPERIMENTS made on the Engine Plane at Eppleton Colliery, on the
Friction of the Pope, Pope Wheel, and Sheaves.—March, 1855.
Number Number Distance Inclina-
Weight
-r, ° • ^ °i Time of traversed Total tion per
Kate of ot- OBSERVATIONS.
Experi- Empty Descent. WTubs Descent. Yard
Inclination. Tubs ment. Tubs. '
Min. Sec. Eeet. Feet. Inches.
lbs.
1 6 2 — 35 1327-2 103-1 2-79 1 in 12-9
2778 Set Stopped.
2 5 3 — 40 1122- 94-5 3-03 1 .. il-85
2315 Ditto.
3 5 2 — 45 1219-2 99-7 2-9 1 .. 12-23
2315 Ditto.
4 5 2 — 50 11G7- 97-4 3- 1 .. 12-
2315 . Ditto.
Aver" } 5 2 — 45 1169-4 97-2 3- 1 in' 12-02 2315
age.
S_________________,______________________________,________________.
The size of rope was 3 inches in circumference, weight 3'75 lbs. per
yard, being a wire rope. The rollers on which the rope runs upon the
plane are 14 in. in length, 3^ in. in diameter, and the axles g in. in
diameter— weight 32 lbs. They are placed 8 yards apart. Diameter of rope
roll of engine 8 ft. 5 in., diameter of axle 9J in. Weight of rope roll
4 tons. The plane on which these experiments were made is shown in Figs.
II. and III., Plate II. In all these cases the train of tubs came to
rest. The number of tubs usually run down at a time when in working is
21; but they do more than overhaul the rope, as the brake is obliged to
be used. In these experiments the trains were set in motion from the top
of the plane, the whole of the rope being upon the rope rolls, and the
distance traversed was from the top of the plane.
In this experiment the length of rope was 390 yards, weight 1462*5 lbs.
j the weight of rope roll, axle, &c, 4 tons; of rope upon the roll, 5910
lbs.;
2315 of sheaves or rollers, 1615 lbs. The moving power was -—— = 193
lbs.;
and supposing the friction of the tubs .the l-82nd part of the weight=
2315
-go~ = 28 lbs., and 193 — 28 = 165 lbs. the moving power, which
dragged the rope 390 yards in 2 min. 45 sec.
283
No, 2.—EXPERIMENTS made on the Friction of the Pope on the Engine Bank,
Eppleton Colliery.—May 10th, 1855.
¦go's
*Sb o| Dis- len,gth Total d
%*%
8S £H tance ot *°l1e Length g
Weight g § |
JI JU Time. traver-0"™aneofIlope * Batio of
of * 3 S OBSERVATIONS.
g S. g-S. sedby ™h™ on |
Inclination, Tubs. g<g£
^« IS ni„h/ the Set Pial„ £
§ ° g
fcW AM lubs- Started. e H
I S fe
Q~ is
Min. Sec. Yards. Yards. Yards. In. lbs.
Yards.
---------------------------------------------------------L------------
1 29 4 — 5 654 1101 1755 946 1 in 25-10 13427 200
Stopped.
2 35 4 — 30 379 1548 1927 471 1 .. 28-80 16205 28 {
J^iStS<?t
I at the bottom.
3 35 5 — 0 389 1544 1933 485 1 .. 28-80 16205 22 Stopped.
4 39 3-45 393 1562 1955 498 1 .. 28-4 18057 .... {£§?££*!
5 35 3 — 35 468 1487 1955 602 1 .. 28-12 16205 .... Stopped.
This experiment was made upon the same plane as the preceding, but it
was commenced with the quantity of rope given in the fifth column on the
plane before the train was put in motion, and the experiment was
performed in this manner; the number of tubs given in the second column
was attached to the rope, the brake was removed, and the set put in
motion; the 4th column shows the distance which the gravity of the tubs
dragged the rope before they came to rest. In the 4th experiment the set
run into the landing.
In this experiment the length of the rope was 1955 yards, weight 7331
lbs., the weight of the rope rolls, &c, 4 tons, the weight of the
sheaves 9192 lbs., (there being in the 1955 yards, 270 rollers 32 lbs.
each, and 23 sheaves 24 lbs. weight each).
18-057 The moving power was, in the 4th experiment, 9^04 = 637 lbs.,
the
friction ^~- = 220 lbs., and 637 - 220 == 417 lbs., the moving
power which dragged the rope 1955 yards in length, 393 yards in 3
minutes 45 seconds; and taking the 5th experiment would be 375 lbs. in 3
minutes 35 seconds, but in this case the train stopped, therefore the
power was barely sufficient to drag the rope to the end of the plane.
Vol. III.—April, 1855. p p
284
No. 3.—EXPERIMENTS ynade on an Engine Plane in the Minor East Pit at
Iletton Colliery.—March, 1855.
Number Number Distance „, , Inclina- _ .
Weight
of of Time of traversed Total tionper Bate
of of OBSERVATIONS.
Bxperi- Tubs. Descent. jjy jubs. Descent. Yard.
Inclination. Tubs, ment.
Min. Sec. Feet. Feet. Inches.
lbs.
1 19 o — 44 837 5-15 2-20 1 in 16-4
9329 Set stopped.
2 20 1 — 9 105-6 6-22 2-09 1 .. 17'2
9830 'Ditto.
3 21 3 — 57 777- 39-34 1-82 1 .. 19-8
10311 Ditto.
4 22 3 — 11 881-1 44-05 1-83 1 .. 19-7
10802 Ditto.
5 23 2 — 55 1165-5 58-63 1-80 1..20- 11294
Set ran into
landing.
The plane on which these experiments were made is shown in Figs. V. and
VI., Plate II. The engine is placed near the shaft at a, the rope is
taken along the horizontal part of the plane from a, to d, and the empty
tubs passing down the plane from a, to C, overhauls the rope from a, to
b, as well as down the plane from d, to C. The length of rope from a, to
d, = 2838 feet, is therefore to be added to the length from d, to C,
viz., 1165 feet, to determine the whole amount of friction. The rope was
2J inches circumference, weight 2| lbs. per yard, length 1334 yards.
There are 60 rollers on which the rope runs from a, to d, 3| inches
diameter, axles g inch diameter, weight 24 lbs., and there are 35
sheaves 9| inches diameter, axles | inch, weight 24 lbs. The rollers
whereon the rope runs from d, to C, are 10 inches long-, 3J inches
diameter, axles | inches diameter, weight 24 lbs., 53 in number. There
are 7 drums at the curve 18 inches diameter, axles 2 inches diameter,
and weight 407 lbs. The diameter of the rope wheel of the engine is 4
feet 6 inches, the axle 4-25 inches, weight 4480 lbs. The number of tubs
usually run at a time is 24, which requires the brake to be used.
In this experiment the length of the rope was 1334 yards, weight
3002 lbs., weight of the rope rolls 4480 lbs., of the sheaves and
rollers
11*294 3559 lbs. The moving power in the 5th experiment was —p7j— =
11-294 5647 lbs., and the friction .....^Q = 188 lbs. Then 564 -
188 =
376 lbs., the moving power which dragged the rope, 1334 yards in
length, 390 yards, in 2 minutes 55 seconds.
285
No. 4.—EXPERIMENT at Killingworth on the Friction of the
Rope of a Fixed Engine.—April, 1855.
In this case the engine is on the surface, and the rope is taken down
the
shaft. It passes over a sheave 8 feet in diameter at the top of the
pit,
it is then taken down the pit, 350 yards deep, then passes around a
sheave 5 feet 5 inches diameter at the bottom of the pit, and then along
a drift, nearly level, 923 yards in length, to the top of the engine
plane.
The gravity of the empty tubs down this plane drags the rope along the
level and down the plane, 30 being run at a time, and the engine drags
the loaded tubs up the plane.
Practically the weight of the rope in the shaft overhauls the rope from
off the rope-roll of the engine, the brake having to be applied to
prevent it from over-running at the bottom. The resistance to the
gravitation of the tubs is therefore, the friction of the rope and
sheaves along the level road, and upon the engine plane.
The circumference of the rope is Sgths inches, weight per yard 5 J lbs.
There are 25 ordinary rollers on flat, 5 inches diameter, axles f inch,
weight 30 lbs. each, and 86 sheaves 7 inches diameter, axles f inch,
weight 25 lbs.• and on the engine plane 84 ordinary rollers 30 lbs.
each, and 5 friction sheaves 11 inches diameter, axles 1 inch. The
length of the plane being 1048 feet. The rope is, therefore, 2770 +
1048 = 3818 feet, or 1273 yards x 5J = 7001 lbs. weight, and the weight
of the sheaves 5545 lbs. It is found that 6 empty tubs overhauls the
rope, and will take it to the bottom of the engine plane• the weight of
the tubs being 2777*4 lbs., and the plane 1 in 5*485. The gravity,
therefore,
1 is 2777-4: x jy^gk = 5°6-3 lbs., from which deduct the friction, which
has been previously found to be -g^nd part of the weight = 33*87 lbs.,
consequently the power required to overhaul the rope was 472*43 lbs. The
following Table will show the result of the foregoing Experiments.
SIS?* Movlt ^of011 ^ITJ ^ngth of Weight of Weight of Weight
of r°LEe„t. J££f carriages. sKsf A- ¦*•¦
Sh— ¦*•*«•
lbs. lbs. lbs. Yards. lbs.
lbs. lbs.
1 165 54 i 111 390 1462
1615 8960
2 637 220 417 1955 7331
9192 8960
3 564 188 376 1334 3002
3559 4480
4 506 34 472 1273 7001
5545 6720
28.6
Taking the aggregate result of these experiments, we find the total
moying power of the 4 experiments to he 1376 lbs, the total weight of
rope 18*806 lbs., making the moving power equal to y^th. part of the
weight of the rope; and the weight of the sheaves being 19*911 lbs. ^
the moving power is equal to the -rf-^th part of their weight; and the
weight of the rope and sheaves together being 38*707 lbs., and the
moving power 1376 lbs. = ^g-. It appears therefore that, when the moving
power is equal to the ^th part of the weight, it will drag the rope over
sheaves and rollers similar to those used in the experiments, at an
average speed of about five miles an hour.
I have not gone into the theoretical calculation of what part of the
moving power was due to the production of the descent of the trains in
the times given by the experiments, and so to determine the statical
amount of friction. The practical utility of these experiments is
intended to show what power, in the everyday application of such planes
is required to produce a certain effect in a given time, the dynamical
result being what is required.
It would appear, from these experiments, therefore, that with 35 tubs, a
length of plane may be worked nearly 2000 yards in length, at an
inclination of 1 in 28, without having recourse to a tail rope. If it be
not convenient or advisable to work with such a number of tubs, then
recourse must be had to a tail rope, or the line of the plane must be
made at a greater inclination.
We have previously seen, that with self-acting planes an inclination of
1 in 30, appeared to be the limit to which this description of motive
power could be extended; these experiments appear to show that an
inclination of 1 in 28, is the limit to which engine planes can be
extended, where the empty tubs have to drag the rope after them; beyond
which it becomes necessary to resort to the use of a tail rope, and
engine power to extend the system of underground transit.
In arriving at the above result, I have not taken into consideration the
gravity of the rope upon the plane, which, to a certain extent, would
increase the moving power. In the two first cases the entire length of
rope was upon the descending plane, and therefore the gravitating force
would be represented by sin I X \ weight of the rope.* But in the two
latter cases only a portion of the rope was upon the plane, the other
portion being on the level part of the road, the former portion only in
these cases must therefore be taken into the calculation. If the
gravitation of the rope in these experiments is added, the aggregate
resistance would be increased 380 lbs., and, consequently, the friction
would be equal to the -r-f.^- part of the weight.
287
PIXED STEAM ENGINES.
I shall now give the details of the experiments made, for the purpose
¦of ascertaining the power and capabilities of the different
descriptions of engines, applied to the various kinds of planes,
heretofore alluded to.
1. Experiments on Engines dragging coals from the dip with a single
rope.
1. Hetton Colliery. Engine in Eppleton Pit. This is a common
high-pressure beam engine, with one cylinder thirty inches diameter,
five feet stroke, on first motion with two rope rolls, similar to 1, 2,
Plate III., which are alternately put in and out of gear. The total
length of the plane at present is 5865 feet, with an average inclination
of 1 in 19*65. There are two boilers, each six feet diameter, and thirty
feet long. The engine is placed underground; the rope rolls in a line
with the plane. The distance from the boilers to the cylinder is 176
feet, requiring that length of steam pipe, which is 7\ inches diameter.
The steam from the cylinder is discharged into the flues by a pipe 86
feet in length and 7| inches diameter.
The plan and section of the plane are given in Figs. I. and II., Plate
II. It will be seen that there are three rails above the meetings and
two below, and that there are several landings or points from whence the
coals are brought by the engine. The mode of working this plane is as
follows:—While the engine is dragging up the loaded set by one roll, the
other roll is put out of gear, and the empty train is run down to the
meetings, and immediately the loaded train passes, the empty train is
run down to the landing, where another train of loaded tubs are ready,
so that immediately one loaded set is drawn to the top of the plane, the
other roll is thrown into gear, and another loaded set started from the
bottom. The rolls whereon the rope winds are each 8 feet 5 inches in
diameter when empty, and when all the rope is on 9 feet 3 inches, the
mean diameter being 8 feet 10 inches. The diameter of the axle is 9J
inches. Their weight is 4 tons. The rope is 3 inches in
circumference, and 3f lbs. per yard in weight. The total length of
rope is 2000 yards. The rope runs upon rollers, placed in the middle
of the railway, 14 inches in length, 3| inches in diameter; the axle g
in. diameter, and 32 lbs. weight each. They are placed about 8 yards
apart, and there are 270 of such rollers on the plane, with 23 rollers
10 inches long, 3i inches diameter, axles g inch diameter, and 24 lbs.
weight.
This engine has been erected some years, otherwise I should have
preferred two cylinders.
288
No. 1.—EXPERIMENT made on the Performance of the Fixed Engine at the
Eppleton Pit, Hetton Colliery.—March, 1855.
No. of Experiment. No. of loaded Tubs. Time of Experiment.
Pressure of Steam per Square Inch, in Length of Plane.
Total Descent ofPlane. Inclination of Plane. Weight of loaded Tubs.
OBSEKVAT.
Boiler. Steam Chest. Exhaust Pipe.
1 21 H. M. 11-53 •54 •55 •56 •57 •58 •59 •59i lbs.
41-5 41-39-38-5 36-35-34' 36- lbs. 42-5 34-37-36-39-5 "38-5 37-36-5
lbs, 5* 5-5-8-8-7-5 7-5 Feet. 3531 Feet. 213-8 1 in 16-52
30,520 From the 3rd south way. 158 double strokes of Engine.
2 21 12-8 •9 •10 •11 44-41-41-39- 45-38-43-40- 7** 7-7-
1760 1 in 16- 31,421 From the 1st north way. 80
double strokes of Engine.
3 21 12-20 •21 •22 •23 •24 •25 44-43-42-5 42-40-37'
46-38-40-42-40-5 39- 8-8-8-8-8- 2709 167-3 1 in 16-19
30,826 From the 2d South way. 124 double strokes of. Engine.
4 21 12-38 •39 •40 •41 •42 •43 •44 ¦45 •46 44-43-5
42-41-39-38-37-35-33- 46-5 38-43-41-39-38-37-36-34- 8-8-8-8-8-8-8-8-
5865 298-5 1 in 19-65 30,681 From the 5th south way. 272
double strokes of Engine.
6 21 1-51 •52 •53 •54 •55 •56 •561 32-32-31-31-30-29-29-
30-5 28-31-75 31-5 30-5 29-5 29- 4-4-5 5-7-5 3531 213-8
1 in 16-52 31,290 From the 3rd south way. 158 double strokes of
Engine.
6 21 2-4 •5 •6 •7 •8 •9 •10 •11 •12 •13 •131
37-36-35-35-34-33-32-31-31-30-29- 36-5 36-36-35-34-33. 31-5
81-30-29-29- 5* 6-7-7-7-7' 7-7-7-7- 5865 298-5 1 in 19-65
31,010 From the 5 th south way. 272 double strokes of Engine.
289
No. 1 Experiments continued.
N£ot No. of *£.-_ loaded pen- ni..},, ment. luDS' 7 21
Time of Experiment. Pressure of Steam per Square Inch, in
length Total Descent of Plane. Inclination of Plane. "Weight of
loaded Tubs. OBSERVAT.
t,~m„_ Steam Boiler- Chest.
Exhaust Pipe. Plane.
H. M. 2-21 •22 •23 •24 •25 lbs. 37' 36-5 35-35-34*
45-44-5 42-42-40-38-37- lbs. 37-29-37-35-34- lbs. 3* a-7-7- Feet.
2709 Feet. 167-3 Iinl6-19 lbs. 31,479 From the 2d
south way. 124 double strokes of Engine.
8 21 2-47 •48 •49 •50 •51 •52 •53 46-41*
44-42-41-39-36-5 4-5-6-7-8-6- 3531 21-38 1 in 16-52
30,905 From the 3d south way. 158 double strokes of Engine.
Table I, of the results of the foregoing Experiments.
POWER.
Number of Experiment. Diameter 0 Cylindej Area of Piston. Pressure
of Steam per Exper. Total Amount of Power in pounds. length
of Stroke of FUton. No. of Strokes per Exper. Space passed
over in feet. Total Amount of Power in pounds, moved one foot.
Inches. Cubic In. lbs. Feet.
1 30 706-86 37- 26153-8 5 316 1580
41,323,035
2 41-5 29334-6 160 800
23,467,705
3 41- 28981-2 248 1244
36,052,691
4 39-2 27708-9 544 2720
75,368,200
5 30- 21206- 316 1580
33,505,100
6 32-8 23185- 544 2720
63,063,200
7 34-4 24316- 248 1244
30,249,080
8 41-2 29122-6 316 1580
46,013,700
290
" RESISTANCE/
"
NunJbero ¦?, f i'riction Prinf°n G^vity hJoUl f
Space Total Amount of
of Gravity of f of - '
Amount of D1™£,iove_. Resistance
Experi- Load. Carria!res Kope, -
Resistance p " f . in pounds, moved
ment. carriages. SheaveSj &c_ ivope. in
pounds_ in teet. Qne fQot
lbs. lbs. lbs. lbs.
1 1847-3 372-2 328-72 55-71 2G03-93 3531
9,194,476
2 1963-8 383-2 163-60 28-64 2539-30
1760 4,469,168
3 1904- 375-9 252-2 43-61 2575-71
2709 6,977,600
4 1561-3 374-2 546-0 77-80 2559-30
5865 15,010,280
5 1889-2 380-6 328-72 55-71 2654-23 3531
9,372,071
6 1578-1 376-9 546-0 77-80 2578-80
5865 15,124,680
7 1944-3 378-1 252-2 43-61 2618-21
2709 7,092,732
8 1870-7 383-9 328-72 55-71 2639-03 3531
9,318,417
The general performance of this engine is equal to 22 per cent., but it
will be observed that the pressure on the exhaust pipe was about 7°,
the-average pressure of the steam 37°, therefore 37° — 7° = 30°; and as
30° : 37° :: 22 ; 27 per cent. But it must also be remarked that the
plane is not uniform, and that though the average inclination is 1 in
19*65, in one portion near the top, as will be seen by the section, the
inclination is 1 in 9. Taking No. 6 Experiment this would give a
performance of 39*5 per cent, on that part of the plane, which added to
5 per cent, for exhaust steam, gives 44*5 per cent. On this part of the
plane, likewise, the diameter of the rope roll is the largest, as almost
all the rope is upon it; and it should also be observed that the
pressure of steam at that part of the experiment was below the average;
the actual efficient performance in this part of the experiment would,
therefore, be about 60 per cent, of the pressure of steam on the piston.
KlLLINGWORTH ENGINE.
This is a common beam high pressure engine, having been formerly used
for drawing coals. It is placed on the surface, and the rope is taken
down the pit, 175 fathoms deep, then along a nearly horizontal piece of
road about 800 yards in length, and then used for dragging the tubs up.
the plane. The cylinder is 25 inches diameter, 5 feet length of stroke.
On second motion, driving wheel 4 feet diameter, and wheel on rope roll
291
8 feet 4 inches. The plane is single, therefore only one rope roll is
used,
9 feet diameter, at starting, and 9 feet 4 inches when the rope is upon
it. There are two boilers, each 6J feet diameter, 23 feet long, with
hemispherical ends. Length of fire grate 4 feet 8 inches, width 4 feet 6
inches. The boilers are placed near the cylinder, the steam pipe being
38 feet in length, 6 inches diameter.
The plane is a single line 1,048 feet in length, with an inclination of
1 in 5*485. The rope wheel being thrown out of gear, the empty tubs
overhaul the rope to the bottom of the plane.
The dimensions of the rope roll, sheaves, and all the particulars
regarding the resistance of the rope, is given in the No. 3 Experiment
on the friction of ropes.
No. 2.—EXPERIMENT made on the performance of a Fixed Engine at
Killingworth.—April, 1855.
*, ^ £ Pressure
W 2 "o 3 Time of of Steam Length Descent Inclination
Weight
"g S Q.-g Experi- per Square of of
of of loaded OBSERVATIONS.
0 S fe'S ment. Inch in Plane. Plane.
Plane. Tubs. |z; P< _o Boiler.
Min. Sec. lbs. Feet. feet.
lbs.
1 30 1 30 47* 1048 192-3 1 in 5-485
36,290 From landing-ex-
treme south way. 1 0 46-5
1 30 45-5
2 0 44-5
74 double strokes
of engine.
2 30 43-5
3 0 42-5 3 30 42-
Table II, of the Results of the foregoing Experiments.
~~ POWER.
\Z S meter Area of 0, „ Amount of of
«*"w passed . OIJ owef>
0 « under. periment. * lbs* Wston-
periment. ieet- Poot.
Inches. Sqr. Inc. lbs. Teet.
1 25 490-875 44-5 21844- 5
148 740 16,164,560
________________________________________________________
Vol. III.—April, 1855. q q
292
RESISTANCE.
Number «_._,*_ -n,,;,.*;™ Friction «__¦*.. Total
Amount Space Total Amount
of Ex- Gra"ty Pnchon of Ropej Gravity of
p/ssed of Resistance
peri- T°. n„™s„„„0 Sheaves, -„° „
Resistance over in in Pounds,
inert. Load- Carriages. &c_' Rope. jn
lbfc Feet< Moved0ne Foot,
lbs. lbs. lbs. lbs. 1 6618- 442-6 448- 351-
7859*6 1048 8,236,860
The performance here is nearly 50 per cent, of the moving power. The
engine being* placed at bank there will be no deduction for the exhaust
pipe, and the plane being1 uniform, the above may be considered
the maximum performance.
i
Springwell Engine.
This engine is also a common beam engine, placed underground, the rolls
in a line with the plane. The cylinder is 22 inches diameter, length of
stroke 4 feet. On second motion, the diameter of the driving wheel being
2 feet 8 inches, and of the wheel on the rope roll 5 feet 2 inches.
There are 2 boilers, each 6 feet 1 inch diameter, and 16 feet 4 inches
in length j length of fire-grate 4 feet 8 inches, width 3 feet 8 inches.
The boilers are placed near the cylinder, requiring only 20 feet 6
inches of steam pipe, 5§ inches in diameter. The steam is discharged
into a small pit, by pipes, 30 feet 6 inches in length and 6 inches
diameter.
The plane is a single line of railway, 4890 feet in length, with an
average inclination of 1 in 15. The rope wheel being thrown out of gear
when the loaded set reaches the top, the empty tubs run down and drag
the rope after them. There are several landings from whence the coals
are brought up the plane.
The rolls whereon the rope winds is 7 feet diameter at starting, and 1
feet 6 inches diameter when all the rope is upon the roll; the axle is 8
\ inches, weight 3920 lbs; rope 2| inches circumference, and weight 3|
lbs per yard; the total length 1630 yards. The rope runs upon rollers 14
inches in length, 4 inches diameter; the axles % inch diameter, and the
weight 28 lbs each; they are placed 9 yards apart, there being 180 upon
the plane.
294
resistance"
B«*« _ ,. . Friction Erlc"on Gravity .
TotaI , Space Tot^ A,"ount of
of Gravity of f of f '
Amount of j\ Resistance ¦
Experi- Load. Ciminsea Hopes, R
Resistance v<*. .. , in pounds, moved
ment. damages. gheaveS; &c. "ope. in
poundg. in teet. 0ne foot.
lbs. lbs. lbs. lbs.
1 2216- 386-4 369- 370- 3341-4 4612
15,410,536
2 2216- 386-4 369- 370- 3341-4 4612
15,410,536
3 2232- 386-4 369- 383- 3379-4 5335
17,981,084
________________________________
The average performance of this engine is 53:4 per cent, of the pressure
of the piston; and, if we take into account that the plane is not quite
uniform, the maximum performance will be above 55 per cent.
No. 2.—EXPERIMENTS on Engines dragging Coals along Levels.
where Horses were formerly used.
Elemore Engine, Hetton Colliery.
This engine and the boiler is placed underground. The construction of
the engine is the same as that shewn in Figs. I., II., and III., Plate
III., viz., with 2 cylinders placed horizontal on a bed plate; but there
are only two rope rolls. The cylinders and engine are placed
underneath
the railway, the ropes being brought out to the level of the road. The
cylinders are 12 inches in diameter each, 2 feet stroke. The rolls are
on
the second motion, driving wheel 2 feet 6 inches diameter, wheel on roll
4 feet 6 inches diameter. The diameter of roll at starting is 4 feet 6
inches, and when the rope is all on the roll 5 feet. One boiler 5 feet 4
inches diameter, and 31 feet long, with hemispherical ends. Fire
grate
5 feet in length, 5 feet 6 inches in width. The engine is placed at a
considerable distance from the boiler, the steam pipe being 313 feet in
length and 5 inches diameter. But there is a steam receiver placed
immediately over the cylinders, 56 cubic feet in area. The steam is
exhausted into the furnace drift by two pipes, each 4 inches diameter,
and 336 feet in length.
The plane has a double line of rails the entire distance, and the
engine, by the two rope rolls, draws a loaded set of tubs out towards
the shaft with one rope roll, and at the same time draws an empty set of
tubs in the other direction by a tail rope passing around a sheave or
wheel at the extreme end of the plane. The diameter of the rope rolls is
4 feet 6 inches, the axles 4| inches, weight 15 cwt. each j diameter of
sheaves for tail
295
rope 4 feet, axle 2| inches, weight 2 cwt. The two main ropes are 2%
inches circumference, weight 3 lbs per yard; wire tail rope If inches
circumference, weight 1| lbs per yard. The rollers on the straight line
of way are 14 inches long and 3J inches diameter, axles g inch in
diameter; there are 260 on the two lines 32 lbs weight each, with 21
large drums and 25 small, weights respectively 407 lbs and 210 lbs, at
the curves; diameter of former 18 inches, latter 12 inches, axles 2
inches.
The plan and section of this plane are given in Figs. VI. and VII.,
Plate II., from which it will be seen that the plane has a considerable
curve in it, and that it is by no means a favorable line for the
application of a steam engine. It was originally a horse road, and was
converted into an engine plane, and shows under what circumstances
engine power can be applied. The section of the line, also, it will be
seen is not at all uniform, but comprizes all the undulations which may
fairly be deemed to be requisite to meet the ordinary undulations of the
strata, and also that of a water level.
296
No. ±.—EXPERIMENTS made on the Fixed Engine at Elemore Colliery, with a
Tail or double Mope.—March, 1855.
Xo. of Experiment. Number of Tubs. Time of Experiment.
Pressure of Steam per Square Inch Length of Plane.
Descent of Plane. Inclination of Plane. Weight of Tubs.
Obsesvat.
At Boiler. At Receive]
¦3 o "S. |
Loaded Empty.
1 25 26 H. M. 9-45 •46 •47 •48 •49 •50 •51 lbs.
SI-»¦ 30-5 30-5 30-5 30-5 31- lbs. 31-25 29-25 28-5 28-75 29-29-31-25
Feet. 3873 Feet. 19-2 1 in 201-72 lbs. 36,089 lbs.
11,778 From end of Plane. 470 double strokes of each Cylinder.
2 25 24 10-2 •3 •4 •5 •6 •7 • 7A • 2 •8 36-35-5
35-34-33-5 32-5 32* 36-25 34-25 33-25 32-25 31-25 30-75 30-5 31-5
3873 19-2 1 in 201-72 35,983 10,872 From end of Plane. 470
double strokes of each Cylinder.
3 25 24 10*19 •20 •21 •22 •23 •24 •24i 35-5 34-5 33-5
32-5 32-31-32- 35-25 32-75 31-75 31-25 30-5 29-75 31-5 3873 19-2
1 in 201-72 38,406 10,872 From end of Plane. 470 double strokes of
each Cylinder.
4 25 23 10-33 •34 •35 •36 •37 •38 •39 •40 34-33-5
32-5 32-31-5 30-5 29-5 29- 34-32-75 31-80 31-25 30-25 29-25 28-5
28-5 3873 19-2 lin201-72 35,801 10,419 From end of
Plane. 470 double strokes of each Cylinder. ,
5 23 24 10-47 •48 •49 •50 •51 •52 •53 •54 •54|
32-32-32-5 33-33-5 33-5 33-5 33-25 34. 32-31-5 31-75 32-20 32-5 32-75
32-75 32-9 34- 3873 19-2 lin201-72 32,935 10,872 From end
of Plane. 470 double strokes of each Cylinder.
297
No. 4 Experiments continued.
1470 double strokes of each Cy-j linder.
299
ment was, however, made to ascertain the ultimate performance of the
engine rather than the practical working result, therefore the former
must be taken as the practical efficient performance. The gravitation
has, however, been taken on the average of the entire length of the
plane, whereas it will be seen by Plate II, Fig. VII, that it is not
uniform, and this will give an increased performance of both loaded and
empty trains, on the level part of the former, and on the greater
inclination of the latter. %
East Minor Pit Engine, Hetton Colliery. This engine is similar in
construction to the Elemore engine, both engine and boilers being
underground, and having two cylinders placed, together with the rope
rolls, on bed plates. The cylinders are 9 inches in diameter; length of
stroke 2 feet. The rolls are on the second motion, the diameter of the
driving wheel being 2| feet diameter, and that on the rope wheel shaft
4| feet diameter. The diameter of roll at starting is 4| feet diameter;
and when rope is on 5 feet 4 inches diameter. Two boilers each 5 feet 4
inches diameter, and 24 feet long, with hemispherical ends. These
boilers, however, supply another engine. Length of fire grate 5 feet,
and width 5 feet 4 inches. The engine is 139 feet from boilers,
requiring 139 feet of pipe, 6 inches diameter. This engine has no steam
receiver; the steam exhausts into upcast shaft 30 feet distant, with 5
inch pipe.
The plan and section of this plane is shown in Figs. IV and V, Plate II.
It consists of a single line, with a double line where the loaded and
empty trains pass. It was formerly a horse road, and the section, it
will be seen, js not uniform. Coals are brought from different
points, and likewise from another engine plane to the dip, of sufficient
descent to drag a rope the whole length of this plane, and of the plane
to the dip. This plane is worked by a tail rope, which runs upon sheaves
placed alongside the railway, and which passes around the wheel at the
end of the plane, as shown in the plan. The diameter of the tail rope
wheel is 4 feet, axle 2| inches, weight 2| cwts. The length of rope
is three times that of the length of the plane, viz. 3,900 yards, wire,
circumference 2J in., weight per yard 3 lbs.; the tail rope being the
same size as the main rope. The diameter of the tub wheels is 7*5
inches, diameter of axles 1-3775 inches; the same as No. 2 experiment,
page 252. There are on the main road 122 rollers, 10 inches long, and
26, 14 inches long, both being 3 J inches diameter; diameter of axles |
inch, the weight being respectively 24 lbs. and 32 lbs. And for the
tail rope 140 rollers and 13 sheaves, diameter of former 3| inches, and
latter 9| inches, diameter of axles | inch, weight of each 24 lbs.
Vol. III.—April, 1855. r r
300
No. 5.—EXPERIMENT made on the Fixed Engine with Tail Rope, East Minor
Pit, Hetton Colliery.—March, 1855.
<m « o .a . '-< jg.5, 1 Number of Tubs. Time o Experiment.
Pressure of Steatr f per Square Inch Length of Plane.
Descent of Plane. Inclination of Plane. Weight of Tubs.
OBSERVAT.
« 9 Hi I Boiler. Engine.
Loaded. Empty.
24 H. M. 8-53 •54 •55 •56 •56| lbs. 46-5
46-46-46-47- lbs. 45. 44-5 44-5 45-46- Feet. 1494 Feet.
5-46 1 in 273-62 lbs. 33,312 lbs. From first ¦west
inclined plane. 174 double strokes of each Cyl.
2 24 9-4 •5 •6 •7 •8 •9 •10 •11 •12 49-47-5 46-45-5
45-44-5 44-5 44'5 44-5 44-75 44-25 44-5 44-43-5 43-5 43-25 43-5 44.
3853-5 16-2 1 in 237-87 11,160 From 2nd west
inclined Plane. 430 double strokes of each Cyl.
3 24 9-17 •18 •19 •20 •21 •22 •23 45. 44-5
44-43-42-41-5 42- 44-43-25 43-41-5 41-40-5 41- 3853-5 16-2
1 in 237-87 33,312 From north inclined Plane. 410 double
strokes of each Cyl. From north inclined Plane. 430 double strokes of
each Cyl.
4 25 9-32 ¦33 •34 •35 •36 •37 •38 •39
49-49-48-5 48-48-47-5 47-47- 48-25 47-75 47-47-46-25 46-46-46-25
3863-5 16-2 1 in 237-87 11,625
5 6 26 9-44 •45 •46 •47 •48 •49 •50 46-46-45.5 45.
44-5 44-44- 45-44-5 44-43-43-43-25 43-75 3863-5 16-2 1 in
237-87 36,088 From north inclined Plane. 410 double strokes
of each Cyl.
24 9-59 10-•1 •2 •3 •4 •4.| 47-46-45-5
44-44-43-5 43-5 45-5 45-5 43-75 43-42-75 42-5 43- 2838 14-68
1 in 193-32 11,160 From Engine way to east. 330 double
strokes of each Cyl.
301
No. 5 Experiment continued.
I a, Number of (pressure of Steam! *
o -------------.
o 'A 7 Tubs. Time of per Square Incl " *
J Feet. 2838 F Inclination | WeiSht of Tubs
OBSERVAT. From En-
¦g 1 ^ ment.
of
OS 3 1 'S Boiler lbs. 44-44- Engine lbs. 43-5
43- Plane. Loadec . Empty lbs. 3 *•
25 1 1 H. M. .. 10-9 •10
Feet. 14-68 1 in 193-32 lbs. 34,70
j •11 43-5 42-5
g-ine way
•12 •13 42-41- 41-5 40-5 J
to east. 300 double
•14 •15 41-41-5 40-5 41-25
1 strokes of each Cyl.
1 j •16 •17 42-42- 41-5 42-
juouia just bring- set
8 •• 1
in273-62 ------- out.
24 10-23 •24 48-47-5 46-5 44-75 1494
5-46 11,160 From first
46- 1 44-25
west in-
•26 •27 •27^ 44-5 44-44- 43-25 43-43'
clined Plane. 215 double strokes of
5-46
each Cyl.
9 23 •• 10-31 •32 45-5 45-5 43-44- 1494
lin273-62 31,924 . • From first
•33 45- 43-5
1 west in-
•34 45- 44-
1 ciined
•33 44-5 43-5
i.rL'dne-
1-174
double
• 1
strokes of 1 1 each Cyl.j
10 •• 24 10-45 I 44-5 •46 44' 43-5
38525 1 16-2 |l 42-25 in 237-87 ..
U,160|From north
•47 44-•48 43-5 43-42-75
inclined Plane.
•49 43-5 42-25
•50 1 43- 1 42*
430
•51 42-5 41-5
strokes of]
1 -52 1 42-5 1 42- 1
each Cyl.j
303
The efficient average performance of this engine is 33 per cent, of the
pressure of steam on the piston, but the result, with the loaded
carriages, is 37*8 per cent., and with the empty carriages 28'3 per
cent. On examining the section it will he seen there is, for about 150
yards, an inclination of 1 in 100, which on that portion of the road
would raise the performance to nearly 50 per cent., and with the empty
carriages there is an inclination of 1 in 38 for about 90 yards, which
raises the performances on that part of the road to 37 per cent.
KlLLINGWOTtTH ENGINE.
This engine is of the same construction as the East Minor Pit, and the
Black Boy engine, Plate III, having, however, only two rope rolls. Two
cylinders 12 inches diameter each, 2 feet stroke. The engine is on the
second motion, diameter of driving wheel 2 feet 3 inches, and of wheel
on roll axle, 4 feet 6 inches. The diameter of the rope roll is 4 feet
6 inches at starting, and 5 feet when rope is on. The engine is placed
at the bottom of the pit, 350 yards in depth, and the boilers at bank.
There are 3 boilers, diameter 5 feet 1 inch, length 34 feet, including
the hemispherical ends. Length of fire-grate 4 feet 8 inches, and
width 4 feet. The boilers are 150 feet from the top of the pit, from
which the steam is conveyed by pipes 10J inches in diameter, then down
the shaft 690 feet, and 36 feet to a receiver No. 1, with 10J inch
pipes. Then with 5 inch pipes from the receiver No. 1 to the shaft
again, 36 feet; down the shaft 360 feet further, and 34 feet to receiver
No. 2, and from thence 35 feet to the engine. The entire distance from
the boilers to the cylinders being 1341 feet; which are 1050 feet below
the level of the boilers. The reservoir No. 1 is 13 feet in length and 5
feet 2 inches diameter inside, and No. 2, 5 feet in length, and 3\ feet
in diameter, exclusive of hemispherical ends. The pipes are wrapped with
felt, 1 inch thick, and covered with asphalte. The exhaust steam is
conveyed by 6-inch pipes from the engine up the shaft 360 feet and level
95 feet, and is then discharged into the shaft 690 feet from the
surface. The steam pipes from the boilers passing down the latter
shaft, the temperature is about 85° j but the small pipes from receiver
No. 1 pass down the downcast shaft, up which water is drawn in tubs 12
hours in each day. A great condensation, as will hereafter be seen,
takes place, the temperature near the pipes being 70° to 85°, and 44° in
the other parts of the shaft, besides water continually dropping on the
pipes.
The plane which this engine works is about 700 yards in length, there
304
being three points from whence the coals are brought. It is a single
line, with a tail rope running on the sid e of the way. There is,
therefore, one length of rope on each roll, and the tail rope or
2770yards, circumference 2§ inches, wire, 2J lbs. weight per yard. The
diameter of the tail rope sheave is 5 feet 4 inches, axle 2^ inches,
weight 6 cwt. There are 112 rollers on the main road, 5 inches diameter,
axles f inch, weight 30 lbs. each; and. there are 127 sheaves for tail
rope, 7 inches diameter, axles f inch, weight 25 lbs. each.
307
RESISTANCE.
Number Friction friction Gravitv
Total ' Snace Total Amount of
of Gravity of *™™n of GraPty Amount of
Da;PaC0ever Resistance
Experi- load. r<arria„es Rope, Eonp
Resistance »V „ in Pounds, moved
ment. 0amages' Sheaves, &c. Kope' in
Pounds. m *eeU One Foot.
------------------------------------------,-----------------------------
--------.-----
lbs. lbs. lbs.
1 107- 170- 481- ___ 758 1181-4
895,010
2 257- 407- 481- .... 631
1181-4 745,463
3 111- 170- 481- .... 762
1946-3 1,483,080
4 290- 442- 481- ___ 633
1946-3 1,232,080
5 100- 170- 481- --- 751
2178- 1,635,680
6 265- 450- 481- --- 666
2178- 1,450,550
7 111- 170- 481- --- 762
1946-3 1,483,080
8 282- 430- 481- ___ 629
1946-3 1,224,220
The average performance of this engine is about 20 per cent, of the
pressure of the steam on the piston. The engine is, no doubt, too
powerful for the work to be performed, the steam being reduced in its
passage to the cylinders. And it will be seen that the velocity of the
pistons was very great, equal to 370 feet per minute.
Andrew's House Engine, Marley Hill Colliery. This is an engine of an
entirely different construction from any of the preceding, a Ground
Plan, FroLt Elevation, and End View being shewn in Plate IV., Figs. I.,
II., and III., and a general description of which has been hereinbefore
given. The two cylinders are 13 inches diameter each, length of
stroke 24 inches; on second motion, driving wheel 2 feet 10 inches
diameter, and wheel on sheave shaft 4 feet 10 inches diameter. The
diameter of the 2 vertical friction sheaves is 5 feet, and of the
horizontal sheaves 4 feet 4 inches. One boiler works the engine,
being placed at bank, 28 feet long, and 6 feet 4 inches diameter;
evaporating surface 23,426 square inches. The fire grate is 6 feet
long, 4 feet 4 inches wide. The steam is taken down the pit in pipes 5
inches in diameter; the depth of the pit is 87 yards; the boiler being
39 yards from the top, and the engine 11 yards from the bottom of the
pit; the distance the steam is conveyed is therefore 137 yards, 87 of
which are vertical. There is a receiver at the bottom of the pit, 5|
yards from the engine, area 97*716 cubic inches.
Vol. III.—April, 1855. s s
308
The plane which this engine works, as shewn in Plate III., Figs. VII.
and VEIL, is double,, with an endless rope. The sheaves are 5 inches
diameter, axles g inch, weight 12| lbs, and there are 316 on the plane.
There is a small carriage goes in front of the train, on which is placed
a clamp to lay hold of the rope. This carriage weighs 6 cwts. 3 qrs. 7
lbs j wheels 14 inches ; rope 2000 yards, 2§ inches circumference,
weight per yard, 3 lbs.
EXPERIMENT made on Fixed Engine, with Endless Rope, at Andrew's House
Colliery.—March, 1855.
——'----------------------~~ ¦ '
¦»
u----------------~~~
o"S No. of Tubs. Pressure of Steam
Weight of Tubs.
u S ________ Time of per Square Inch. Length Descent Inclination
% I Tl ~ Bxperi- ______________ of of
of OBSERVAT.
S ^ S £• ment. Plane.
Plane. Plane.
^H ' 1 f Boiler. Receiv.
Loaded. Empty.
____________________________________________________________
M. s. lbs lbs. Feet. Feet.
lbs. lbs.
1 14 14 Comen'c. 28-' 28- 2788:5 22-45 1 in 124-2
20,594 8,330 From end of 0-30 28- 27-5 •
Plane.
1- 27-75 27-
1-30 27-75 26-75
293 double
2- 27-5 26-5
strokes in 2-30 27-5 26-
each Cyl-
3- 27-5 26-75
inder. 3-30 27-25 26-75
4- 27-25 26-75 4-30 27-25 26-75
5- 27- 26-5 5-30 27- 26-5
2 14 14 comenc. 27*5 87* 27885 22-45 1 in 124-2
20,594 8,330 Prom end of 0-30 27-25 26-5
Plane.
1- 27-25 26-
1-30 27- 26-
293 double
2- 27" 25-75
strokes in 2-30 26-75 25-
each Cyl-
3- 26-5 25-25
inder. 3-30 26-5 25-
4- 26-25 25-4-30 26- 25-
5- 26- 25-5-30 26- 25-
3 14 14 Comenc. 26-75 27* 2788-5 22-45 1 in 124-2
20,594 8,330 Fromendof 0-30 26-5 26-25
Plane.
1- 26-5 26-
1-30 26-5 25-75
293 double
2- 26-25 25.75
strokes in 2-30 26-25 25-
each
Cyl-
3- 26- 25-
inder. 3-30 26- 25-
4- 26- 25-4-30 25-75 25-
5- 25-75 25-
5-30 25-75
25-_____________________________________________________
309 Table VII, of the Result of the foregoing Experiments.
POWER.
Number Dia- . „ Pressure Total of ^"f4"
No. of Total Amount
of meter of „,£,„„ of Steam Amount °* Strokes
sPace of Power in
x Bxperi- each ™J™ per Power st™ke
per passed over pounds, moved
ment. Cylinder llslons- Exper. in pounds. pit^ns
Exper. wfeet. one foot.
Inches. Sq. In. lbs. Feet.
1 13 265-46 26-8 7114-32 2 586 1172 8,387,983
2 ...... 25-5 6769-23 .. 586 1172 7,983,537
3 ...... 25-5 6769-23 .. 586 1172 7,933,537
RESISTANCE.
Number Friction Friction Gravitv
Total „ Total Amount of
of Gravity of ™lon of 6rli™? Amount
of DJWver Resistance
Experi- Load. Harrises RoPe> I Rone
Resistance ' . f , in pounds, moved
ment. Carriages. sheavegj &c- -Kope. ,_
pounds- in teet. Qne foot_
lbs. lbs. lbs.
lbs.
1 99 396 383 48
728 2788-5 2,029,928
3 99 396 383 48 728
2788-5 2,029,928
3 99 396 383 48 728
2788-5 2,029,928
The average performance of this engine is 25 per cent., but there is a
considerable amount of friction by the rope being so tightened by the
stretching apparatus at the two ends of the plane. It will be seen
however by Plate I, Fig. VIII, that for a distance of nearly 200 yards
there is a rise of 1 in 100 with the load, and for a distance of 154
yards a rise of 1 in 73 with the empty carriages j, which makes the
performance nearly 40 per cent, on the passage of the trains over those
portions of the road.
No. 3.—EXPERIMENTS on an Engine dragging Coals along Levels, and also
along a Crosscut to the Pip, and likewise pumping Water.
Black Boy Colliery. The form of this engine is given in Plate III, Fig
I, being a Ground Plan, Fig. II, a Front Elevation, and Fig. Ill, an End
View. The two
310
cylinders are 12 inches diameter each, 2 feet stroke; on second motion,
driving wheel 3 feet 4 inches diameter, and wheel on rope roll axle, for
both sets of rolls, 6 feet diameter. There are 4 rope rolls:—two, for
the Howlish plane, 5 feet 6 inches diameter at starting-, and 6 feet 6
inches when rope is on—and two, for the Woodside plane, 4 feet 6 inches
diameter at starting-, and 5 feet 10 inches when rope is on; axles of
rope rolls, 5 inches. The engine is placed at the bottom of the pit, the
boilers being* at bank. 3 boilers, 311 feet long, 5\ feet diameter; 26J
feet long, 5\ ¦ feet diameter; and 25 feet long, 5 feet diameter
respectively; but two only are at work at a time. Evaporating surface
173*25 feet, 167'75 feet, and 125 feet respectively. Fire grate 5 feet 3
inches long, 4 feet wide. The boilers are distant from the engine, 10
yards from pit, 130 yards down the shaft, and 20 yards to reservoir, =
160 yards. Steam pipes 8 inches diameter; reservoir 12 feet long, 3 feet
diameter, 11 yards from engine; pipes 5 inches to cylinders. The exhaust
steam is conveyed up the shaft to bank, in pipes 10 inches diameter; the
pit being a downcast shaft.
A plan and section of the planes which this engine works are shewn in
Plate J., Figs. X., XI., and XII., it is a double line of road to where
the Woodside plane branches off, and then both planes are single. Both
planes are worked by main and tail ropes, the ropes in both cases being
three times the length of the respective planes. The Howlish main rope
1100 yards, and tail rope 2200 yards, both 2 inches circumference, If
lbs per yard; Woodside main rope 1100 yards, 2| inches circumference, 3
lbs per yard; tail rope 2200 yards, 2 inches circumference, If lbs per
yard. The rollers for the main roads are 4 inches diameter, axles g
inch, weight 16 lbs each; sheave at end of planes 3 feet 9 inches
diameter, axles 3 inches, weight 6 cwt; sheaves for tail ropes h\ inches
diameter, axles | inch, weight 18 lbs each. There are 76 rollers and 72
sheaves on the Howlish plane, and 96 rollers and 91 sheaves on the
Woodside plane j with 6 drum sheaves at turn of the Woodside plane, each
3 feet diameter, axles If inch, weight 3 cwts.
311
EXPERIMENT made on the Fixed Engine at Black Boy Colliery.—April, 1855.
^ «j Pressure of Steam *-.
"g
W g Number w;ma «c Per Square Inch, ° £ *• <S
Inclination Weight
¦S 8 of t, lime °* ______________ ¦S § 2 §
of of Observat.
SI Tubs. ExPel'iraent- -------------------- I?! gg
Plane. Tubs.
£ ft Boilers. Reserr. £
P
m. s. lbs. lbs. Feet. Feet.
lbs.
1 40 commenc't. 38- 36- 2865 7* 1 in 382
13,440 From shaft to Empty 0-30 37-5 35-5
the How-Tubs.
1- 37- 34-75
lishBank. 1-30 36-5 34-5
2- 36-5 34-25
270 double 2-30 36- 34-
strokes in
3- 36- 34-
each Cy-3-30 36- 34-
linder. 4-18 36-
34-
2 40 commenc't. 37'5 36- 2865 7*C 1 in
382 44,230 From shaft to
Loaded 0-30 37-5 35-75
Howlish Bank.
TUbS' J'™ Ill ll'll
270dble.Strks.
I'M J7-5 37-75
in each Cylind.
2- 37- 35-5
2-30 37- 35-25
Ordinary day's
3- 37- 35-
work from 3-30 37- 34-75
se^oflb tubs
4- 37- 35-25
each.
3 80 commenc't. 38- 35-5 2076 4- 1 in 519
88,460 Prom 5-quar.
Loaded 0-30 38- 35-5
staPIe t0 sha£t-
Tubs. 1* 38- 35-25
196dble.stroks
1-30 37-75 35-5
in each cylind.
2- 37-5 35-5
Ordinary day's
2-30 37-5 35-5
work from 5"
o. o7.k ok.7c
quarter staple,
X„rt At ° 60 '° . , „,
14 sets of 40 3-30 37-5 36- Eng- me s
topped at Siding, tubs each,
4 18 commenc't. 38- 36"25 2850 38- 1 in 75
6,048
Empty 0-30 38- 36-
_ m , ,.
Tubs. 1- 37-75 35-75
iTw.f
3-30 37-75 35-5
each Cv
4- 37-75 35-5
f. j1 VJ 4-30 37-75 35-75
under.
5- 38- 36-
5 18 commenc't. 37-5 36-25 2850 38- 1 in 75
19,908 Prom Wood-Loaded 0-30 37-5 36-
i%Bank to Tubs.
1- 37-25 35-
asHble strks 1-30 37-25 35-
™nj&&
2- 37-25 35-
linder. 2-30 37- 35-25
Ordinary day's
3- 37. 34-75
work from 330 37- 35-
J-^ 3-45 37. 35-5
tubs each.
312
Table VIII, of the Results of the foregoing Experiments. _
power. ~~~
Number Dia- . nf Pressure Total Length
jfo. of Q„0„a Total Amount
¦ of meter of rf£rr° of Steam Amount of °*
Strokes ^£5°® of Power in
Experi- each ^^ per Power Stroke
per passedover poundS) moved
ment. Cylinder ",luer!>- Exper. in pounds. pis"ns
Exper. ln teet- one foot.
Inches. Sqr. Inc. lbs. Feet.
1 12 226-19 34-5 7803-5 2 540 1080 8,427,780
2 ...... 35-5 8029-7 .. 540 1080 8,672,076
3 ...... 37-5 8482- .. 397 784 6,649,888
4 .. .... 35-7 8075- .. 578 1156 9,334,700
5 ...... 35-3 7986- .. 578 1156 9,231,816
RESISTANCE.
Number TMtMim Miction fir„vitv
Total - Total Amount of
of Gravity of En$on of GraJ^ Amount of
***Zev Resistance
Experi- Load. C,BJLS. ~&oVe, °*
Resistance PT7 °t? M m pounds'moVed
ment. damages. SheaveS) &c< Kope. in
poundg, in itet. Qne foQt
lbs. lbs. lbs.
1 35- 164- 251- ....
450- 2865 1,289,250
2 116- 540- 251- ....
675- 2865 1,933,875
3 171- 1080- 251- .... 1160- 2076 2,408,160
4 81- 74- 372- .... 527' 2850 2,001,950
5 265- 243- 372- .... 880- 2850 2,508,000
The average performance of this engine on both planes is only equal to
24 per cent, of the pressure of the steam on the pistons. The
performance in the 3rd Experiment is, however, equal to 36*2 per cent,
on the average inclination of 1 in 519 in favour of the load, whei'eas
on a portion of the road the inclination is against the load. On the
Wood-side plane the average inclination is taken, whereas for 274 yards
the inclination is 1 in 40, which raises the performance up to 34*4 per
cent.
Besides the above performance of 344 per cent., the engine raises by
means of a crank upon the axle of the sheave a, Plate I, Fig. X, a
column of water 20 feet in height. The working barrel is 10 inches in
diameter, the length of stroke 2 feet, and the sheaves a, being 3 feet
S"
313
inches diameter; the piston of the pump makes 280 strokes for every
train drawn in each direction. The length of the plane of {his engine is
now extended.
GENERAL RESULTS OF THE FOREGOING EXPERIMENTS.
The practical conclusion resulting from these experiments appear to be,
that in the application of engines of the first description, page 276,
Viz., Engines drag-ging coals from the dip with a single rope, and where
the inclination is such that the empty set of tubs or waggons drag's the
rope out from the engine; that these engines are capable of realizing an
efficient performance equal to 50 per cent, of the pressure of the steam
on the piston.
And, Engines working on planes requiring a tail rope, working round a
sheave at the end of the plane to drag the empty set and main rope out
from the engine, pages 276 and 277; the efficient performance may be
safely calculated at 40 per cent, of the pressure of the steam on the
piston.
These conclusions are arrived at on the supposition, that with wheels of
a diameter of 12 inches, the friction of the carriages is equal to the
¦g^nd part of the weight; and that with wheels of 7| inches in diameter
the friction is equal to the -^vd part of the weight; and that where the
diameter of the sheave to that of the axle is as, 4 : 1, the friction of
the rope and sheaves is equal to the -Jg-th part of their weight. Any
variation, by lessening the amount of friction of the carriages, or by
an increased diameter of the sheaves ', will, of course, affect the
results, and must be considered in arriving at a correct conclusion.
While, however, as above explained, the engines are capable of yielding
an efficient performance of 50 and 40 per cent, of power respectively;
it will not be advisable in practice to erect engines, the nominal power
of which is not greater than 50 per cent, above that of the efficient
performance, calculated on the principles of the foregoing calculations.
It will be advisable, probably, that the practical or efficient
performance, should not be calculated at a higher standard than 30 per
cent., or about one-third of the pressure of the steam on the piston,
the velocities of the load, and of the piston being equal.
314
GENERAL SYSTEM OF MECHANICAL CONVEYANCE OF COALS UNDERGROUND.
Having determined the powers and capabilities of the different
descriptions of motive power which may be employed in the conveyance of
coals underground, we can now apply them to an imaginary coal field ;
for the purpose of showing, that by one or other of the applications of
those mechanical powers, and with the aid of horses only as auxiliaries
to those powers, the coals from any part of such coal field can be
conveyed to the bottom of the pit.
Let us suppose the space within the square ABCD, Plate I, Fig. I, to
represent a coal field of four square miles in extent, the pit P, being
• in the centre thereof; and suppose the coal beds to lay at an angle of
4° 50' or 1 in 12, rising in the direction AB, and DC, the water level
line being at right angles thereto, along the lines AD, and BC. The
extreme distance from the pit, to the full rise or dip, and water level,
being, consequently, one mile.
1st.—We have found that the margin of the action of the self-acting
plane is 1 in 30. Let the lines Pa, and Pb, represent an inclination of
1 in 30. Then all the coal above tbose lines, or within the area Pa, Bcb
P, is capable of being conveyed to the pit P, by self-acting planes,
either by the plane Pc, direct to the pit, which will be an inclination
of 1 in 12; or by other planes, such as Pa, or Pb, or by the short
planes de and fg, to the lines Pa, or Pb ; and so by the planes f P, and
dP, to the pit. The coal within the area PhBCiP, can also be conveyed
down to the roads Ph, and Pi, by the self-acting planes ha, kl, mn, or
ib, and so to the pit by the roads Pkh, or Pmi, worked either by horses
or engine power, as hereinafter explained.
2nd.—We have ascertained, likewise, that with the carriages, or tubs, as
at present constructed, the inclination of a road, to be worked by
horses, and to produce a maximum effect, must be laid out at an
inclination of 1 in 130. Let the lines Ph, and Pi, represent such roads;
then if horses are employed, the coal within the area PhaP, and PibP,
will be conveyed along such roads to the pit P. It is not absolutely
necessary, as will be hereafter shown, that horses should be employed on
these roads, as in the cases of the Elemore, East Minor, Marley Hill,
and Killing-worth collieries, fixed steam engines are employed. If,
however, the dis-
315
tances are short, or the quantity of coals to be brought out is small in
amount, and engine power cannot be profitably employed; then these
road&fiat the inclination of 1 in 130, will produce a maximum effect
with horses.
The preceding observations apply to, and embrace, the conveyance of the
coal above the level of the pit, the remaining portion of the supposed
coal field, viz., PhADiP, is to the dip, or deep, of the pit; the
conveyance of which to the pit P, will require fixed engine power.
3rd.—We have seen, that at an inclination of 1 in 28, the empty tubs, or
carriages, will drag out the rope of a fixed engine, without the aid of
a tail rope, similar to the engines at the Eppleton, Springwell,
Killing-• worth, and East Minor pits. Let the lines Po, and Pp,
represent the line of inclination of 1 in 28. Then engines of this
description can be employed for the conveyance of coal on this portion
of the coal field, either direct from the pit, the inclination being 1
in 12, as Pv,—along the lines of 1 in 28, Po, and Pp; or along a portion
of such lines, and then direct to the dip, by the branching planes qr,
and st. And, we have seen that those engines may either be placed at the
top of the pit, the ropes leading down such pit;—or they may be placed
at the bottom of the pit, and in the last case, the boilers may be
either placed on the surface, the steam being convej^ed down the pit in
pipes, or they may be placed with the engine at the bottom of the pit.
This description of engine plane would, therefore, convey the coal to
the pit P, from all the points or stations x, o, r, v, t, p, and z, or
any variation of planes terminating at those stations; and the
self-acting planes wx, o'o, yz, or p'p, would convey the coals down to
the engine planes Po, and Pp;—while the engine planes, as in the cases
of Eppleton, Springwell, &c, would, by landings between P, and V; q, and
r; or s, and t; convey the coals between the line of planes Po, and Pp,
and the horse road vr, and vt, to the pit P. This system of engine and
self-acting planes, comprises therefore, the conveyance of all the coal
situated below the level, or to the deep of the pit to the bottom of the
shaft P, with the exception of the conveyance along the horse roads,
which we shall now consider.
4th.—It has been ascertained, as before stated, that an inclination of 1
in 130, with the present description of carriages in use underground,
will produce a maximum effect, or that the resistance of the loaded tubs
down, will be equal to that of the empty tubs up, such a plane; whether,
therefore, horses or engine power is intended to be used, it is alike
Vol. III.—April, 1855. t t
316
advisable, that this inclination should he endeavoured to be established
on the levels of the mine.
I am aware, that this is a greater rate of inclination than is required
for the water levels, the passages for which may be driven at about 1 in
200. But it is a subject of considerable importance, and will entirely
depend upon the local, or particular circumstances of each mine, if it
be advisable, in order to preserve correct water levels, that the horse
roads should be driven at the same rate of inclination and thereby
subjecting the motive power which convey the coal, for probably several
years, to an increased rate of cost. At all events, having that rate of
inclination which will produce a maximum effect, it must be left to the
judgment of the engineer in charge of the mine, to determine to what
extent the influence of other considerations justifies a departure
therefrom.
Returning to the consideration of the motive power to be used on the
horse roads. We have seen by the experiments hereinbefore given, and by
the description of the engines No. 2, page 294, viz., the Elemore and
East Minor engines at Hetton Colliery, and the Killingworth, Marley
Hill, and Black Boy engines; that those engines are employed on what
were formerly the horse roads of those collieries. These description of
engines will, therefore, by providing for the conveyance of the coals
from those portions of the coal field not hereinbefore provided for,
complete the system of conveyance of coals by fixed engines underground;
and, with the aid of self-acting planes, will show by what means the
whole of the coals, in such a coal field as that represented by Plate V,
can be conveyed to a central pit P, without the aid of horses, except as
auxiliaries to those mechanical powers, at the landing of the different
planes. And I may adu, that this is only necessary in few cases, as in
all ordinary cases the roads may be so arranged that the different
planes may be worked with each other, and at the bottom of the pit,
without the aid of horses.
I have, in the last description of engine power, purposely given
examples of those planes where the curves are very considerable, and
where the planes are by no means in a straight line, such as the Elemore
and Black Boy planes; and where, likewise, the undulations are very
considerable, beyond that where the tubs or carriages will run of
themselves, and where they would over-run the hauling rope, were they
not prevented from doing so by the tail rope.
These curves and undulations show, that the application of such planes
may be varied to a considerable extent from those of straight lines, and
from planes of uniform gradients; and are such as will meet almost, if
317
not entirely, any case between the self-acting plane of 1 in 30
descending^ and engine power of 1 in 28, where the gravity of the tubs
will overhaul the rope.
It cannot, however, be assumed that the case brought forward in Plate V,
represents all the varied circumstances of coal fields in general, where
the occurrence of dykes and faults, disturb the continuance or
regularity of the strata, or where variations of the inclination of the
beds of coal interrupt or break the continuity of planes laid out with a
specific inclination, for the application of a particular description of
motive power. The case is given to illustrate, the particular
application of the different descriptions of motive power; and to show,
in what manner the whole of the coal of such a coal field, can be
conveyed to a central pit by mechanical means.
It would lengthen this paper, much beyond the limits of what is either
necessary or advisable, to go into the consideration of how or in what
manner such variations or interruptions as those above alluded to,
should be met; this must be left to the judgment of the engineer in
charge of the mine, and having before him, besides his own experience,
the principles, and the practical performances of the different
descriptions of motive power, which I have endeavoured to illustrate.
It will be for him to consider, whether any of them, in the ordinary
circumstances of the mine, or whether, with probably a moderate
expenditure of capital; some one or other of those mechanical modes of
conveyance may not be adapted to almost every case in practice, without
having recourse to the expensive and tardy system of horse labour.
And I may, in conclusion, be allowed to point out, that if the
inclination of the beds of any coal field is greater than that assumed
in Plate V; then the margin of the application of self-acting planes to
the rise of the pit; or of engine planes, where the gravity of the tubs
overhauls the rope, will be more extended; and the necessity of horse
powei*, or the application of engine power with tail ropes, will be
correspondingly diminished:—And the triang-les Pab, and Pap, will be
extended; and the triangles Poa, and Ppb, will be diminished. On the
contrary, if the coal field is more level, or less than an inclination
of 1 in 12, then the contrary will be the effect, the triangles Pab, and
Pop, will be diminished in extent, and the triangles Poa, and Ppb, will
be extended in area; and the application of self-acting planes, and
engine power with a single z'ope, will be diminished, and the
application of engine power with tail ropes extended. And, if the
beds of a coal field should be level, or not
318
reaching an inclination of 1 in 28, or 1 in 30; then self-acting planes,
and engines where the gravity of the train is to overhaul the rope,
cannot either of them he applied; and the entire conveyance will have to
he accomplished by either horses, or engines with tail ropes; unless
breaks, or variations in the strata occur, when by a moderate
expenditure of capital, one or other of the other descriptions of motive
power can be applied.
It was my intention, and I had made several experiments for that
purpose, to have investigated the loss of power, by the transmission of
the steam from the boilers to the cylinders; either, by its conveyance
down the pit in pipes, where the boilers are on the surface and the
cylinders underground; ov, by its conveyance from thence, or from the
bottom of the pit, to engines placed at a distance therefrom, but I
found it would have extended this paper too much. I shall, therefore, at
a future time, and as an appendix to this paper, trouble the Institute
with some observations, and experiments on this subject; with a view of
ascertaining, to what distances steam engines can be placed from the
shafts, or in extension of engines conveying coals direct to the shafts,
up which the coals are to be drawn; and thus to determine, how far the
system of engine power can, in deep pits and expensive winnings, be
economically extended, in substitution of the sinking of such pits or
winnings.
319 NOETH OF ENGLAND INSTITUTE
OF
MINING ENGINEERS.
MONTHLY MEETING, THURSDAY, MAY 3, 1855, IN THE ROOMS OF THE INSTITUTE,
WESTGATE STREET, NEWCASTLE-UPON-TYNE.
T. J. Taylor, Esq., in the Chair.
The minutes of the Council having been read,
The Chairman apologised for the absence of the President, and the
meeting proceeded with the election of gentlemen proposed at the
previous meeting, and after the votes had been taken, the following were
elected :—Mr. Robert Cadwallader, Ruabon Colliery, Wrexham; Mr. William
Hynde, Ruabon Iron Works, Wrexham; Mr. Samuel Dobson, Newport, Monmouth;
Mr. William Hobbs Ware, the Ashes, Stanhope.
The Chairman then said, that the first business before them was the
discussion regarding the paper of Mr. P. S. Reid, on " Blowers of
Explosive Gas," in order that the objection of Mr. Atkinson to a
calculation in the paper be fairly considered and settled. As Mr. Reid,
however, was not present, he (the Chairman) did not think they could
with propriety enter upon the subject, and there appeared no alternative
but to adjourn the consideration of the subject at issue until the next
meeting. In the absence of Mr. Reid he thought they might devote their
time in discussing the summary of Mr. Atkinson's paper " On Mining
Science," and with that view he should be glad to hear any observations
from any gentleman present.
Vol. III.—May, 1855.
320
Mr. M. Dunn suggested, that it would he better to postpone the subject
until they had before them Mi*. Wood's observations on it.
The Chairman—Then, in that case, he would have to adjourn the meeting1,
as there was nothing* else before it for consideration.
Mr. Dunn—If so, perhaps Mr. Atkinson would oblige them with a brief
summary of the subject.
Mr. Atkinson thought it would be a difficult task to do so, as he had
not seen the paper since he wrote it and sent it to the Institution. lie
should, therefore, prefer reading the whole of it.
The Chairman suggesting such a course,
Mr. Atkinson then proceeded and read the paper.
At the termination of the reading of this paper, the Chairman suggested
that the discussion of it be postponed until the next meeting, which was
agreed to.
Mr. Berkley, previous to the meeting separating, called attention to the
importance of the Institute being furnished with Parliamentary papers
connected with the Coal Trade, and proposed the following resolution on
the subject:—
" That this Institute do purchase copies of all Parliamentary papers
connected with the Coal Trade, whether they refer to the mine
engineering- department, the export of coal, foreign or home, or
statistics of the Coal Trade generally, that may from this date he
puhlished : and that it is also desirable that when any of the
before-mentioned Parliamentary documents are published, notice of such
publication shall be given to the members in the Monthly Circular, and
that any member wishing to purchase such publications, shall, by
signifying such wish to the Secretary, within one month of receiving the
notice, be provided with a copy of such publication, if the same can be
obtained. Each member to pay for his own copy the price charged by the
publisher."
The motion having been seconded and agreed to, the meeting separated.
321
SUPPLEMENTARY MATTES
TO A PAPER ON
THE THEORY OF
THE VENTILATION OF MINES,
COMMUNICATED TO THE NORTHERN INSTITUTE OF MINING ENGINEERS, IN
DECEMBER, 1854, BY JOHN J. ATKINSON,
PROPOSED FOR DISCUSSION
BY THE MEMBERS OF THE INSTITUTE.
CHAPTER I.
In the introductory remarks, it is stated, on general principles, that a
knowledge of the correct theory of the art of Ventilating Mines may
reasonably be considered to have the following beneficial effects on the
practice of the art.
1st.—That of freeing practice from an amount of empiricism, which
is presumed to prevail, in the absence of such knowledge. 2nd.—That of
having a general tendency to lead to improvements in the practice of the
art; both directly, by reasoning and induction j and by enabling us to
devise and carry out experiments having the same end in view, on
systematic and correct principles; and also by enabling us more
correctly to generalize the results of any such experiments and to draw
true inferences from them.
3rd.—That of saving useless expenditure in trying unsuccessfully to
carry out new and impracticable arrangements for the Ventilation of
Mines, on the one hand; and at the same time, of
322
enabling us to select and determine, a priori, what are the best
arrangements for ventilating particular mines.
As the usefulness of the paper depends, to some extent, upon the
correctness of the above views, and as their confirmation by the members
of the Institute might have a tendency to increase the degree of
attention paid to the subject, perhaps some of the members may express
their opinions as to their correctness or the contrary.
Although most of the laws enumerated as affecting the Ventilation of
Mines may be regarded as being well established and generally received,
yet some of them do appear to be worthy of discussion by the members of
the Institute on the present occasion. Amongst those may be named (6),
(7), and (8), taken in connexion with Note V, in the Appendix; because
the great simplicity and generality of the law which may be considered
as the general resultant of these laws, is such, as in itself to form
one of the principal keys to the acquirement of an easily retained
knowledge of the laws of ventilation: the generality of the law, of the
pressure required to overcome the resistance being proportional to the
area of the rubbing surface presented to the moving air, when other
conditions are constant, renders it useful for finding the pressure
required to overcome the resistances occurring in passages of almost
every form and area of section: and the law of the pressure per unit of
surface (8), being, further, inversely proportional to the area or
number of units of surface of section over which it is to be
distributed, when the velocity of the air in the passage is supposed to
be constant, (proportional to the square of the velocity, when it is not
constant), is both simple and general in its application.
Laws (9), (10), (11), (12), (13), and (14), may, perhaps, also be
considered as deserving a passing notice in the discussion, when taken
in connexion with the remarks which accompany them; as it appears as if
experiments are yet wanting for their complete elucidation; or perhaps
some of the members may be able to throw light upon the doubtful points,
without making any special experiments for the purpose of determining
them.
CHAPTER II.
This chapter has reference to the discharge of fluids under pressure,
through orifices or short tubes; and the pressure due to the generation
of motion, considered apart from pressure due to frictional or other
323
resistances; and although so far useful, perhaps does not present any
particulars requiring discussion here.
CHAPTER III.
In this chapter, perhaps some of the following matters may be deemed
worthy of discussion.
Section (18), so far as regards the final velocity in elastic fluids
passing through confined passages, being the only velocity actually
absorbing pressure except in so far as motion creates friction:—in the
same section the effects of the gravitation of the air, in ascending and
descending parts of an air-way, on the ventilation, are noticed; and
may, if deemed necessary, be discussed.
In Section (19) some doubtful points are alluded to, which perhaps some
of the members may be able to explain; or, on the other hand, be willing
to prove by experiments.
In Section (20) a mode of finding the resistances presented by any "
wastes," returns, or other air-ways in mines, is alluded to, and which
perhaps might be resorted to in some instances with benefit.
In Section (22) it may be seen that in order to prevent the formulas
becoming too intricate, the effects of the extra degree of expansion in
the air, due to a higher, as compared with that due to a lower average
upcast temperature, has only been allowed for in so far as it alters the
ventilating pressure, and not as it tends to increase the frictional
resistance due to a given weight of air passing up the upcast shaft,
this will perhaps seldom affect the correctness of the conclusions
obtained by the use of the formulae, in reference to the Ventilation of
Mines, to any material extent; more especially where the resistance
presented to the air by the upcast shaft forms a very small part of the
entire resistance, encountered by the air, from its entering, up to the
time of its leaving the mine; and again, when the quantities observed as
data, do not differ very widely from those to be calculated for:—yet
particular cases may occur where it is necessary, from the limited
distance travelled by the air in the workings of a mine, to make
allowances for the differences of expansion, causing the air to
encounter resistances in upcast shafts, which are not proportional to
the square of the volume of cool air circulating in the unit of time;
and the following note was sent too late to the printer for insertion in
the Appendix to the Memoir; as having reference to such cases, besides
being useful for calculating the dimensions required in flues or
chimneys, Vol. III.—May, 1855.
v v
324
traversed by air having different temperatures, in different parts of
their extent, in order that they may be capable of circulating a given
quantity of air.
Note on the Mode of Calculating the Corresponding Pressure and Discharge
of Air in Mines, Flues, and Chimneys where different temperatures
prevail in different portions of the routes traversed by the air:—
In mines which have only a small extent of air-ways to be traversed by
the air, before being expanded in volume, by the heat of a ventilating
furnace; and in flues or chimneys of manufactories, or engines, it will,
perhaps, sometimes be desirable to make the necessary allowances for
the# effects produced on the resistances, by changes in the degree of
expansion ; and thus also on the volume and velocity of the air
discharged ; in any calculations relating to the quantity of air
circulating in a given time. In order to exhibit a mode of doing this
let the following notation be adopted:—
Let M1; M2, Ms, &c, be the specific resistances of succeeding portions
of the route of the air.
Let the prevailing temperature of the air in such succeeding portions of
the route be Tw T2, T8, &c., respectively.
Let T be the final temperature of the air on its expulsion from the exit
end of the route.
Let Q be the cubic feet of air (taken at its volume as due to some
temperature t, assumed as a standard) discharged per minute, by a
pressure expressed in height in feet of air column of the density due to
the same standard temperature t, such height of air column being
represented by P.
Let A = the area in superficial feet of the exit end of the air-way.
Then, if the air be assumed to start from a state of rest, at the
entrance end of the air-way, the expenditure of pressure in air-column
of the density due to the temperature Tu in that part of the route which
has the specific resistance Mx will, (see (54) &c), be expressed by
which, by [24] is equivalent in pressure, to a column of air having the
density due to the standard temperature t, expressed by,
Q* *59 + T* Ml
y 459 + t Ml
325
By a similar mode of proceeding, we find that the pressure required, in
the part where M2 is the specific resistance, expressed in column of air
of the density due to the standard temperature t, is
M 459 + t M* and where M8 is the specific resistance, we have for the
pressure, in air-column of standard density
459 + T3 y 459 + t m and we could thus find the pressure due to each of
the parts into which the air-way may have been conceived to be divided,
whether the divisions were made to suit changes in the form of the
section of the air-way, or of the prevailing temperature of the air j
and, lastly, the expenditure of pressure, expressed in feet of
air-column of the density due to T, on the generation of the final
velocity with which the air leaves the exit end of the air-way, is, by
[10]
tm + t ^ y
\ 459 + t ^)
231,600 A2 which pressure is expressed in feet of air-column, of the
density due to the standard temperature t, by
459 + T
Q. 459 + t
H 231,600 A* The entire expenditure of pressure expressed in feet of
air-column of the density due to the assumed standard temperature t,
required to circulate the quantity of air Q, reckoned at the volume due
to the same temperature, is therefore expressed by
p=45^r {(459+w+(459 + TJM»+(459 + Ts)Ms &c"+m^}
and hence the quantity of air put into circulation by any assumed
ventilating pressure P is
_______
45Q -I- V J (_59 + T1)MI + (_59 + T2)M2 + (459 + T3)M3&c., .... +
^±±.
The pressure P, must, of course, embrace the entire ventilating
pressure, whether arising in the vertical or inclined parts of the
shafts, airways, chimneys, or flues, as the case may be.
In (24), (25), (26), (27), and more particularly in (28), we have a mode
of finding and comparing the specific resistances of different mines,
which may be useful for calling attention to such mines as greatly
require
326
an improved arrangement for splitting the air; whether sueh improvement
be required in order to increase the amount of air circulating, or
merely with a view of reducing the cost of producing the
necessary-amount of ventilation required in the mine.
The specific resistances of different mines may also be employed, in
order to determine which of any number of modes of producing
ventilation, whether by furnaces, fans, Hartz pumps, or otherwise, will
be the most economical, in any mine of which we may have ascertained the
specific resistance; provided we have the account of the ventilation
produced by the same kind of machine, or power, in any other mine, of
which we also know the specific resistance.
In section (29) rules are given for finding any corresponding upcast
temperatures and quantities of air circulating in the unit of time, in
mines where we have observed one series of corresponding upcast
temperatures and quantities of air.
In section (32) the quantity 1 is assumed to be a constant quantity, or
nearly so, in reference to the loss of temperature by cooling in any
given upcast shaft ; and as the loss in question has an important
bearing upon the determination of the best area, for the mere purposes
of ventilation, to be given to upcast shafts, perhaps some member would
think it worth while making experiments to determine the law of loss by
cooling in upcast shafts.
In (36) it is shown that the quantity of air put into circulation in any
mine, by each lb. of coal consumed, will vary to an enormous extent with
an alteration in the energy of the ventilating power employed, and in
the quantity of air circulating in the unit of time, and hence the
necessity of ascertaining, not only the specific resistance of a mine,
but also the energy or amount of power applied in it to produce
ventilation, before any correct conclusion can be drawn, as to the
comparative economy in the consumption of fuel, of different modes of
producing ventilation, whether such modes are tried at one and the same,
or at distant times, even in the same unaltered mine.
In section (37) we see that the consumption of fuel is very nearly
proportional to the cube of the quantity of air put into circulation in
a given time, in the same mine, and that it is so, whether furnace or
engine power is applied to create ventilation j so that we must consume
8 times the fuel, to obtain twice the quantity of air in the unit of
time; and 27 times the fuel to get 3 times the air in the unit of time j
so long as the state of the mine, and the arrangement for ventilation,
remain unaltered, except in cases where natural ventilation prevails, so
as to alter the proportion alluded to.
827
The loss of power in fans and also in Hartz ventilators has been found
by continental Mining Engineers to be very great; but it may be
questioned whether a large proportion of this loss could not be avoided,
by making the valves and air passages connected with the Hartz
ventilators of large dimensions; and balancing the valves in a proper
manner. As Mr. Struve's ventilating machine appears to be the same in
principle as the Hartz ventilator, it appears to be desirable that
experiments should be made on some of those machines, now in use in this
country, in order to ascertain the loss of power in them.
One form of Mr. Struve's machine has double the number of sets of
valves, and air passages leading to them, which are used in the Hartz
ventilator; and is, therefore, so much the more liable to be deranged;
and this liability to derangement, both in the machine itself, and in
the engine employed to work it, I hold to be one of the principal points
in which the furnace is to be preferred as a ventilating power.
It is true that by doubling the number of sets of valves, as just
alluded to, Mr. Struve professes to obtain a double quantity of air,
from pumps of equal dimensions with those of a Hartz ventilator,- but
as, in such case, the power must be increased to suit the resistance
encountered by the greater quantity of air; and as the same quantity of
air could be got, by the same power, by using a machine of the Hartz
kind, having the linear dimensions of the pumps little more than one and
a quarter times as great as those in a machine constructed on the
modified principle proposed by Mr. Struve; I consider that the old form
of the Hartz ventilator is to be preferred, as being more simple, less
liable to get out of order, and as economical in power.
For certainty and constancy of action, I hold that the furnace is to be
preferred to any machine, or mode of producing ventilation, at present
known; in all cases suited for its application; yet I strongly incline
to the opinion that machines constructed on proper principles, would in
almost every instance, produce ventilation at a less cost in fuel than
it can be produced by furnaces. There are also some cases which admit of
the application of machines, and are ill adapted for the application of
furnace power, for the production of ventilation.
CHAPTER V.
It has, I believe, frequently been laid down as a principle in the
ventilation of mines, that the upcast pit ought to be situated more to
328
the rise of the strata than the downcast pit, for the purpose of
ventilation.
Where the surface of the earth is situated at the same level, at the top
of each of the pits, and furnace action is employed to produce
ventilation, I disagree with the above principle, as a general rule ;
because I think it will generally be found that the upper part of the
upcast column of air will be so much more heated and expanded, than the
air in the ascending workings, between the bottom of the downcast, and
that of the upcast pit, that it will give a pressure, over equal
vertical distances, capable of overcoming more than double the
ascensional power, so to speak, of the air in such ascending workings,
and whatever is to spare, beyond this, will be so much added to the
general ventilating pressure, for an equal consumption of fuel.
Although as regards a level coal district, like that of Newcastle, the
above may be considered as a matter scarcely deserving notice; yet in
other districts, where the pits are not so deep, and where the
inclination of the strata is considerable, it is not so unimportant.
In (44) and (45) we have rules for finding the quantities of air which
will pursue each of a series of routes open to it, by means of the
specific resistances of the routes, when a general and equal ventilating
pressure operates over the whole of the routes.
We also have a mode of finding the resistance due to a passage which
would transmit a quantity of air, in a given time, equal to the total
quantity of air transmitted by the united action of any number of such
routes under the same pressure.
At page (124) we have a tabular statement of the coefficient of
Fric-tional Resistances, presented to the passage of air, by different
substances, against which it may have to move. •
Although in the case of water, the coefficient of resistance is the
same, for all kinds of substances, in contact with which it has to move,
yet, as regards air, it is, on the contrary, found to vary to so great
an extent as to become highly interesting when considered in reference
to the practice of ventilation; as it appears to hold out a prospect of
enabling us to obtain a considerably increased quantity of air in a
mine, by using what may be termed an anti-frictional coating, on the
walls of shafts, and the main air-ways near them, with equal ventilating
powers; or, on the other hand, of cheapening the cost of producing
ventilation, by reducing the friction in the shafts and main air-ways;
and might even save the cost of sinking additional pits, or driving
additional, or larger stone drifts, to increase ventilation.
329
A comparison of Table 2 with Table 4, or of Table 3 with Table 5, will,
at once, show how very important a matter, in the ventilation of mines,
it is to have the resistances in the shafts and air-ways near them,
reduced to their minimum amount. Besides, there would be a saving in the
loss by cooling, if the resistances in an upcast shaft could be reduced
in the manner alluded to, compared with the same amount of reduction if
it had to be effected by the mere enlargement of the shaft itself.
The deep pits in the eastern part of the county of Durham, which have to
penetrate the mag-nesian limestone, before reaching the coal measures,
appear to be suited for the application of the principle suggested, as
they are so costly to sink.
In the Table at page 124, it will be seen that a coating of tar or pitch
on cast iron, requires only about one-fourteenth part of the pressure to
overcome its frictional resistance, which was required to overcome the
resistances of the shafts, and a part of the air-ways of the Crook Bank
colliery, in the experiment made by Mr. G. C. Greenwell in that
colliery; while the resistance offered by brick or pottery is found to
be such, that it, also, requires about fourteen times the pressure to
overcome it, which is required by tar on an equal surface of cast
iron—other things being the same.*
It should, however, be observed that the air was heated in the
experiments by which the resistance of a surface of brick or pottery was
determined, while the air was cool in the experiments which determined
the resistance of a surface of tar on cast iron; and it was heated over
one part, and cool over another part, of the distance traversed in the
Crook Bank colliery experiment; and although M. Peclet, who has made
upwards of 500 experiments on the resistance of air, has concluded that
the frictional resistance is not affected by the temperature of the air,
still I think it might be worth while trying experiments to determine
this, and also to determine the most suitable substance to be used as an
anti-frictional coating for air, particularly, as the best size to be
given to upcast shafts, for the mere purpose of ventilation, depends
partly upon the effects of heat on the frictional resistance; and as tar
or pitch is probably too inflammable a substance to be used as an
anti-frictional coating in an upcast shaft.
* See subsequent remarks on certain errors, arising- from Mons. Girard's
miscalculations, which had not been discovered when the above was
written. The discovery of the error, in the coefficient of Girard, for
cast iron pipes, does not affect the principle alluded to, as other
substances may present even smaller resistances.
330
The coefficient of friction for steam in Mr. Rudler's experiment,
alluded to in Note II, in the Appendix, agrees very closely with that of
air in cast iron pipes, covered with soot, if we presume that the
friction increases in proportion to the barometrical pressure, and if we
take the steam as having" escaped under the pressure in the boiler, in
Mr. Rudler's experiment. As, however, it is not stated that the pipe was
of cast iron in Mr. Rudler's experiment, some doubt may perhaps exist as
to whether this was so or not.
As the friction of steam in pipes has a bearing- upon the question of
the expediency of placing the boilers of an underground engine, in the
mine, or on the surface, it is hoped that the paper now being brought
before the Institute, by the President, may contain some information as
to the loss of pressure arising to steam in traversing long pipes.
Note III, in the Appendix, shows that the coefficient of friction, due
to gas in ordinary gas pipes, as given by Mr. Hawkesley, agrees almost
exactly with the coefficient of friction due to water, as given by Ey
tel-wein, in Note IV.
The construction of the formulae in Notes III and IV agree very closely
with those given in the Memoir.
Note V indicates that an acquaintance with the laws governing the flow
of gas through pipes, was, a short time ago, at any rate, rather
uncommon, even amongst gas engineers; and Mr. Anderson's letter strongly
corroborates the correctness of the formulas given in the Memoir.
The erroneous rules given by Dr. Ure, in his Dictionary of Arts,
Manufactures, and Mines, when treating of the flow of gas through pipes,
confirm the statement of Mr. Anderson in reference to the lack of
knowledge on the subject.
Tables 2, 3, 4, and 5 exhibit, in a general manner, the benefits
resulting from splitting the air in mines, in a judicious manner, when
the splits are nearly equal to each other in every respect.
The shaft resistances in Tables 2 and 3 are taken at a considerable
amount, and equal to many cases which may exist in practice. From Table
2, it appears that, with the same ventilating pressure, upwards of
fifteen times the quantity of air would circulate in such a mine, when
divided into fifteen equal splits, which would have circulated before
splitting the air; so that there would be more air in each split, and it
would only have one-fifteenth part of the workings to ventilate.
In order, however, to realise the above, it would require a consumption
of fuel proportional to the quantity of air circulating in the unit of
time,
331
or nearly so; whether the ventilation were produced by furnaces, or by
engine power applied to a ventilating machine.
In the same mine, it would have required the consumption of fuel, or the
engine power to have increased as the cube of the quantity of air
circulating, to have produced the same amount of ventilation without
splitting the air; thus, the consumption of fuel, and the engine power,
must have been increased to 3,375 times its original amount, to give
fifteen times the quantity of air in the unit of time without splitting.
It appears to be desirable that experiments should be made to ascertain
something like the law by which the consumption of fuel, by any given
furnace, increases, with an increase in the quantity of air passing over
it in the unit of time.
If the fuel burnt by any given furnace increases in the direct
proportion of the quantity of air passing over it in a given time, then
the results given in Table 2 would nearly represent those which would
arise from splitting the air, without making any alterations in the
furnaces by which ventilation is produced.
In Table 3 are exhibited the results of dividing the same example mine,
as is referred to in Table 2 into different numbers of equal splits, as
described in the paper; on the supposition of the power employed to
produce ventilation being constant; and hence, on that of the
ventilating pressure decreasing in the same ratio that the air is
increased, as the resistances become reduced by splitting the air. On
this presumption the fuel consumed in furnace action, would remain
constant; and it would also be realized by an engine applied to produce
ventilation through a machine, or very nearly so.
From this Table it would appear that if an engine, or a furnace
consuming an invariable quantity of fuel in the unit of time, circulated
16,198 cubic feet of air per minute, before splitting, it would
circulate 92,616 cubic feet per minute, in the same example mine, after
being-divided into 9 equal splits, under the conditions named in the
Memoir; each split having 10,291 cubic feet of air per minute in it, and
only having one-ninth part of the workings to ventilate.
Table 4 exhibits the effects of splitting the air in a mine, having the
same extent of workings as that alluded to in Tables 2 and 3, but with
constant resistances, due to the shafts and the air-ways in the vicinity
of the shafts, of much less amounts; under the same constant ventilating
pressure as in Table 2.
Vol. III.—May, 1855. x x
332
A comparison of Tables 2 and 4, exhibit, in a striking manner, the great
benefits which would result to ventilation, either by reducing the cost
of producing a given ventilation, or by increasing the ventilation in
amount, to be expected to result from any means of reducing the constant
resistances in the shafts and adjoining air-ways. A few of the
results-are given in the following tabular statement, in which the
ventilating pressure is presumed to be constant.
With the larger amount of resistances in the With the reduced
resistances in the Shafts,
Shafts, and in the air-ways over which the whole and in the
air-ways through which the whole
of the air passes, in the vicinity of the Shafts, of the air
passes, in the vicinity of the Shafts,
as in Table 2. as
in Table 4.
Total quantity of Quantity of Air Total Quantity
of Quantity of Air
.Number ^ir circulating in each Split Number
^;r circulating in each Split
°f in cubic feet per in cubic feet per °f
in cubic feet per in cubic feet per
Splits. minute. minute.
Splits. minute. minute.
1 7,288 7,288 1 7,302 7,302"
2 20,328 10,164 2 20,623 10,311 4 52,129 13,032
4 57,807 14,452 6 78,568 13,095 6 103,550
17,258 8 94,652 11,831 8 152,770
19,096
10 103,280 10,328 10 200,000 20,000
20 113,704 5,685 20 341,126 17,056
30 114,939 3,831 30 379,472 12,649
40 115,245 2,881 40 390,941 9,774
50 115,355 2,307 50 395,285 7,906
:________________________________________________________
In order to have realised the above results, under the conditions named
in the Memoir, would have required the engine power to have been
increased in the same proportion that the air increased, as also the
consumption of fuel, whether used in an engine, or in ventilating
furnaces.
The results arising in the same mines, as are alluded to above, on the
presumption of the consumption of fuel being constant, are exhibited in
Tables 3 and 5 in the Memoir, and a few of the results are given below.
333
With the larger amount of resistance in thp witi *t ,
shafts and in the air-ways through whic the anT n t iV'edueed
stance in the shafts
whole of the air passes/ £ «J?£*£*
«™ugh which the whote
Number T°tal quantity of Quantity of air
t«*«i
JMiinoer ?lr circulating in each split in Number
T°- f1 <?««*ity of Quantity of air Splits. ln cubic feet
per cubic feet per of taeubteftSES*
ineachsP'»in minute. minute. Splits.
»'cubic feet per cubic feet per __ _
minute.
minute.
1 16,198 16 198 ,
' i 16>!27 16,217
2 32,094 ic)047 2 *> aiu
32,404 16>202
4 W'm I5'°33 * 64,^0
8 89,492 11 187
11,187 8 123,153 U>m
10 94'850 9>4^ 10
147 srr,
10 147,360 14,736
20 101'132 5>057 20 !
21fl««s ,
*W 210,365 10,518
30 101,861 q qqk
3'395 30 225,850 7,528 40 102,042
o SSI
'551 40 230,377 5,759
50 102,106 2 04O Kn
J________J ^'U42 50 232,080
4,641
Now, the differences, in the quantities of air circulating in the two
cases, arises entirely from the resistances in the shafts and in the
airways near them, which are traversed by the whole of the air, being,
in - one case, taken at little more than l-18th part of its amount in
the other case j and when it is considered, that the specific
resistances, allowed to be due to the shafts and air-ways traversed by
the whole of the air, is, in the one case, taken at about l-257th part
of the specific resistances of the divisible workings of the mine, and
in the other case is supposed to be reduced to about l-18th part of its
previous amount, it certainly appears to hold out a fair prospect of
greatly reducing the cost of producing ventilation, or of greatly
increasing its amount, if any suitable anti-frictional substance could
be applied to reduce the resistances in the shafts, and in the main
air-ways near them—the differences in the Tables are little more than
would have arisen from coating* the shaft walls, and main air-ways near
them with tar or pitch, had it been a suitable substance, as it reduces
the friction to about l-14th part of the amount •given by Mr. Greenwell,
as due to the shafts and air-ways in Crook Bank
334
Colliery, as compared with a reduction of no more than to l-18th in the
Tables. If this view as yet, partakes of the theoretical, it does so in
such manner as to warrant the prosecution of experiments to prove
whether it can be made available in practice or not.
In Tables (7), (8), and (9), is exhibited a general view of the
comparative results, in ventilation, to be anticipated from having the
splits of equal and of unequal amounts.
Table 7 presumes the power and consumption of fuel by furnaces to be
directly proportional to the quantity of air circulating in a given
time, and shows a loss of 30 to 46 per cent, in the quantities of air
circulating, when the splits form a series in arithmetical progression,
as compared with the splits being all equal, as stated in the Memoir.
Table 8 presumes the power and the consumption of fuel to remain
invariable, and shows a loss of from 20 to 34 per cent, in the quantity
of air circulating, arising from the same .inequality of the splits.
Table 9 exhibits the great reduction which takes place in the pressure,
power, and consumption of fuel, by judiciously splitting the air when a
constant quantity is circulating, both on the supposition of the splits
being equal, and also on that of their being unequal, and forming an
arithmetical series, having the least split for a common difference,
under the conditions stated in the Memoir. This Table shows that even
when a mine may be considered to be sufficiently ventilated, it may
occur that by improving the mode of splitting the air, the consumption
of fuel, and the cost of producing an equal ventilation, may be reduced
to a small per cent age of the previous cost of producing the same
amount of ventilation.
CHAPTER VI.
Presents for discussion the question as to the practicability of
applying the specific resistances of air-ways, to determine, in practice
the best mode of ventilating a mine in reference to splitting the air.
This chapter also opens the question as to the best mode of ascertaining
the specific resistances of air-ways. Whether by taking the dimensions
of the air-ways, or by observing the differences of pressure, as is
proposed in the Memoir; or by any other mode to be suggested.
Can any member suggest the construction of an instrument to be used as a
pressure gauge or as a barometrical instrument for finding minute
differences of pressure, to a great degree of nicety, and moderately
free
335
from the effects of heat, in altering its indications; or, on the other
hand, admitting of easy and accurate corrections being applied for such
effects ?
Would the Institute deem it worth while to get an instrument of the kind
described in the Memoir, constructed and tried ?
It may perhaps be considered worth the time to discuss the conclusions
arrived at, as to real meaning of the water gauge indications, both in
reference to the air-ways lying between the points of observation, and
also in reference to the shafts and the air-ways extending from them to
the respective points of observation.
CHAPTER VII.
Presents for discussion the formulse for finding the friction of
revolving anemometers, and the mode employed on the Continent for
finding the constants a and b.
CHAPTER VIII.
Contains the illustration of the application of the specific resistances
of air-ways to determine, apriori, the effects of any proposed "change
of air " in a mine.
REMARKS UPON THE PROPORTIONS OF POWER, REQUIRED TO PRODUCE DIFFERENT
AMOUNTS OF VENTILATION IN THE SAME MINE.
It may, perhaps, appear from the following statement, that the
consumption of fuel in ventilating mines, whether by machinery driven by
engine power, or by furnace action; is, under the ordinary circumstances
of mines, nearly proportional to the cube of the quantity of air
circulating in the unit of time, in the same mine.
In the case of machinery driven by engine power, the ventilating
pressure to be overcome is nearly proportional to the square of the
quantity of air circulating, in the unit of time, in the same mine ,*
while the velocity with which such pressure has to be overcome, is
nearly proportional to the simple quantity of air circulating in the
unit of time; the power of the engine, however, in this, as in other
cases, is proportional to the product of the pressure or force to be
overcome, and the velocity
336
with which it is required to be overcome; and since the former is
sensibly proportional to the square of the quantity, and the latter to
the quantity simply, the power and fuel being proportional to their
product, must be nearly proportional to the square of the quantity,
multiplied by the quantity simply, which is, in fact, the cube of the
quantity of air circulating in the unit of time, in the same mine.
As an example, suppose an engine to drive a Hartz ventilator,
exhausting- air from a mine, as by pumping. If we would double the
quantity of air without altering the engine, or machinery, the pumps
would require four times the force to move them, seeing that the
ventilating pressure increases as the square of the quantity of air; and
hence four times the pressure must be exerted on the piston, to overcome
the resistance of the air, and this additional pressure, even if exerted
on the piston travelling at the same speed, would make the power four
times as great; but, in fact, the piston must travel at twice its former
speed, to exhaust the double quantity of air, in the same time; and the
piston, working under four times the pressure, and at twice its former
velocity, evidently represents eight times the original power, as being
required to double the quantity of air; which increase of power is
sensibly proportional to the fuel consumed, and is evidently
proportional to the cube of the quantity of air. To have increased the
quantity to three times its original amount, the ventilating pressure to
be overcome, and hence, the pressure on the piston must have been
increased to 3 x 3 = 9 times its original amount, and in order to
exhaust the treble quantity of air, in a given time, it must have moved
with three times its original speed• and this nine-fold pressure on the
piston, and its three-fold speed, represents a power twenty-seven times
greater than the original power, as being required to circulate only
three times the quantity of air in a given time, in the same mine; so
that the power, and therefore the fuel, are proportional to the cube of
the quantity of air to be circulated in the unit of time, in the same
unaltered mine; except in so far as the same may be effected by other or
natural sources of ventilation, where machinery is employed.
The greater or less degree of expansion, created in the air, owing to
the changes in the amount of ventilating pressure employed, will
certainly affect the volume, and therefore the velocity, of the air, and
thus, the power; but to an extent seldom worthy of notice, when it is
considered that a ventilating pressure of 2 inches of water gauge, will,
in general, alter the volume of air less than l-200th part of its entire
volume, if it were either entirely removed, or doubled in amount.
337
Taking the resistance encountered by a boat on a canal as proportional
to the square of the velocity of the boat—and if we suppose an engine to
drag such a boat, by a towing line folding upon a drum; then, in order
to double the velocity of the boat, the strain on the towing line will
be four times as great as its original amount; requiring four times the
pressure to be exerted on the piston; but this fourfold pressure must be
exerted on the piston travelling at twice its original speed, in order
that the speed of the boat may be doubled, thus representing eight times
the original power, which is proportional to the cube of the double
velocity of the boat, which is the proportion in which the power and
fuel vary, with a variation in the speed of the boat ,• and this is a
case, parallel with that of an engine producing ventilation through
machinery.
In the case of ventilation being produced by furnace action; while the
increase of temperature to be imparted to the air, within moderate
limits, is sensibly proportional to the ventilating pressure to be
produced, such pressure, itself, is nearly proportional to the square of
the quantity of air j and hence the increase of temperature, and the
fuel expended on producing such increase, in an equal quantity of air,
will also be proportional to the square of the actual quantity of air:
but the fuel will evidently be further proportional to the actual
quantity of air in circulation, and requiring to be heated -, so that,
on the whole, I hold, that even in furnaces, the fuel is proportional to
the cube of the quantity of air to be circulated in the unit of time,
except in so far as the proportion may be modified by 1°. A change in
the proportion of fuel due to cooling in the upcast shaft, with changes
in the temperature, and quantity of air circulating.
2°. Changes in the proportion of fuel saved by heat imparted, or lost by
heat abstracted, by the walls of the mine, from the air circulating.
3°. By changes in the specific heat of the air, arising from changes of
temperature, and in the weight of air expelled by heat, from the upcast
shaft, at different temperatures. 4°. By the extra expansion of the air
in upcast shafts at higher as compared with lower temperatures, g'iving
rise to increased resistances, beyond what would be due to air at the
same temperature. So far as these sources operate, they will affect the
ratio of the quantity of fuel, to that of the air circulating, in a
given time, in the same mine; as their effects will be greater, in
proportion, as the quantity of air
338
is lessened; so that the cube of the quantity of air will not be,
strictly, although perhaps in mines where a tolerably energetic
ventilation is kept up, it will be very nearly proportional to the
quantity of air circulating-in a given time.
REMARKS ON CERTAIN ERRORS IN THE PAPER ON "THE THEORY OF THE VENTILATION
OF MINES," ARISING FROM MONS. GIRARD'S MISCALCULATIONS.
Previous to communicating the Paper on the Theory of the Ventilation of
Mines, to the Institute, I had not seen Mons. Girard's detailed account
of his experiments on the Transmission of Air and Curburetted Hydrogen
Gas, through cast iron pipes, and wrought iron tubes- and, consequently,
had to take a brief account of the deductions drawn from them, which I
had in Mons. Peclet's "Traite de Chaleur:" since then, however, I have
been favoured with the perusal of Mons. Girard's detailed account of his
experiments, and this has led me to detect two errors, which I take this
opportunity of correcting.
Mons. Girard appears to have fallen into an error, in calculating from
his experiments, the constant co-efficient of resistance, due to the
transmission of air or gas, through cast iron pipes, and Mons. Peclet,
and myself after him, have given the same erroneous constant.
To correct this error, it is necessary to make the following-
corrections in my Paper on the Theory of the Ventilation of Mines.
1°—Instead of ioo?fl$$iVff7 being the value of the constant k, due to
cast iron gas pipes, as stated in Table i, at page 124, the value of the
constant, according to the experiments, should be T5^'£wi,hru
2°—Instead of the 2nd line of the tabular statement at page 209, of the
Institute Journal, being "Old tarred cast iron J cool |
-000,000,019,050 | 56-664 | 7-5275-"
according to the experiments it really ought to be " Old tarred cast
iron ] cool | -000,000,048,436 | 22-286 [ 4-7208."
3°—Instead of the formula [n], in the tabular list of formulae, at page
210, the true formula to agree with the experiments, is
V = J 331,600 h x 47208jI + 2^286D ......[n]
The second error to which I have to solicit attention is contained in a
statement in Section 10, at page 77, to the effect that the absolute
amount
339
of pressure per unit of surface required to overcome the frictional
resistance of tubes or air-ways, to the passage of air or gaseous
bodies, was found by M. Girard, in his experiments with the gas-lighting
apparatus of St. Louis Hospital, to be the same for the passage of the
gas used for lighting, as for the transmission of air, rendering it
highly probable that it is the same for the passage of all kinds of
gases whatever, through the same pipe or passage.
The above statement would appear to have been made in consequence of M.
Girard's first general conclusion, professing to be drawn from his
experiments, which is to the following effect:—
"1°—That carburetted hydrogen gas and atmospheric air, under the same
state of compression, move after the same laws, and experience exactly
the same resistances in the same tubes, and this independent of their
specific densities," In point of fact, however, the experiments plainly
indicate that for the passage of atmospheric air and carburetted
hydrogen gas, through the same pipes, and under the same pressure the
volumes discharged in a given time, are inversely proportional to the
square roots of their respective densities : that this is the case,
will appear by examining the following statement of experiments made by
Mons. Girard- compared with calculations based upon the above law.
Length of PiDes
Discharges of Atmospheric Air,
in Feet • the
calculated from those observed of
Number pressure ^ unit Numbers proportional to the
Carburetted Hydrogen Gas, tak-
, °f . of surface being observed discharges in the unit
"* the discharges to beinversely
Experi- constant f0* ftt*^
proportional to the square roots
meilt- all the expert-
of tlie densities j and the specific
nt r
gravity of Carburetted Hydrogen as •f>hi, to that of Air as 1.
English Feet. Garb. Hydrogen. Atmospheric Air.
1 & 4 422-58 12,180 9,023
9,074
2 & 5 1233-00 7,103 5,414
5,298
3 & 6 2043-30 5,414 3,947
4,033
Sums.. .................. 18,384
18,405
This conclusion is fully borne out by the other experiments of Mons.
Girard which bear upon this part of the subject.
The experiments, therefore, when considered in connection with the
ascertained fact, that, when other things are the same, the volumes
dis-Vol. III.—May, 1855. y y
340
charged in a given time are proportional to the square roots of the
pressure per unit of surface, lead to the conclusion, that if the
pressure per unit of surface be estimated in height of head of air or
gas, of the same density as the flowing air or gas, then will the
volumes discharged in the unit of time be directly proportional to the
square root of the height of such head or column, when the length of
pipes, or air-ways, and other things, remain constant and unaltered; and
as the formulae given in the Paper on The Theory of Ventilation agree
with this, no further alteration is required, beyond the erroneous
statement alluded to in Section 10, page 77, where the statement ought
to be,
" (10)—The height of head of air or gas column, of the same density as
the flowing air or gas, required to overcome the frictional resistances,
&c," In lieu of
"(10)—The absolute amount of pressure required to overcome the
frictional resistances, &c,"
341 NORTH OF ENGLAND INSTITUTE
OP
MINING ENGINEERS.
MONTHLY MEETING, THURSDAY, JULY 5, 1855, IN THE ROOMS
OF THE INSTITUTE, WESTGATE STREET, NEWCASTLE-UPON-TYNE.
Nicholas Wood, Esq., President of the Institute, in the Chair.
Mr. Doubleday, the Secretary, having read the minutes of the Council
proceedings, then read the minutes of the last monthly meeting; after
which, referring to the resolution passed respecting his instructions to
procure all parliamentary papers on the subject of Mines and Mining, &c,
stated that he had given a general order to Mr. Charnley, bookseller, to
obtain all publications connected with the Coal Trade.
The President then said, they would perceive that the minutes of the
Council contained nothing requiring notice from him, excepting the
subject of the proposed Mining College of Engineers. They perhaps would
recollect that, at a previous meeting, they were informed that a general
meeting would take place in April, in London, of the representatives of
the several districts of the Coal Trade in the kingdom. That meeting, he
begged to inform them, had been held a fortnight ago, at which Mr. T. J.
Taylor and himself were present. The subject of the establishment of the
Mining College having been brought before the meeting, every gentlemen
present was convinced of the great necessity which existed for the
establishing of such a Mining College for the education of mining
engineers and others entrusted with the management of Coal Mines. There
certainly existed some difference of opinion as to Vol. III.—July, 1855.
342
where the College should be established, some contending for the Midland
Counties, and others in South Wales, where mining operations were
extensive, and where it was suggested the College would be valuable as a
means of instruction to persons engaged in both the Coal and Ironstone
Mines j after some discussion, however, the situation of
Newcastle-upon-Tyne appeared so obviously superior to any other, that it
was ultimately agreed that Newcastle-on-Tyn@ was the most suitable place
for such College,, as it was admitted that there were facilities and
advantages all around that district which no other part of the kingdom *
possessed: as, in the Newcastle district, independently of the mines
being more numerous, their greater depth and, consequently, greater
difficulties of management,, presented opportunities for instruction to
the pupils of the College which no other district, in the kingdom
possessed. This point having been settled, another subject of
discussion ai'ose relative to the propriety of establishing* Local
Schools in connection with the College -7 after much discussion it was
finally determined that this question would be more properly left for
future consideration after it was seen how the College progressed in
Newcastle. In the course of the proceedings it appeared evident to
every one that unless the intended College was of a first-rate
character, both in respect to its management, and also with regard to
the Professors, it would not succeed. It was also further represented
that as the object was most important, and would comprehend the
education of a most numerous class of Mining Managers, it was necessary
to have the College established on a broad, comprehensive,, and sound
practical basis. And though there was no doubt that in the progress of
time Local Schools would unquestionably be introduced, still they should
be subservient to the College, and be in the nature of preparatory
schools and feeders to it. Having stated thus much of the proceedings
of the meeting in London, it only remained for him to inform them that a
resolution was passed at that meeting approving of the Mining College,
and of its great utility and importance relative to the future
management of the coal mines in this country, and appointing a committee
to further its establishment. So far as the tone and feeling- of the
meeting in London went, he might say that, as a first meeting on the
subject, it was highly encouraging; and that it was represented by
deputations from almost every mining district in England, Wales, and
Scotland, every one of whom expressed their desire to render every
support to the project. Before separating, the meeting-was informed
that so soon as the mode of carrying out the project was
343
agreed upon, a communication to that effect would be transmitted to all
the districts. The proper course for the Council of the Institute to
pursue, would probably be, in conjunction with the committee appointed
in London, and with other persons and bodies in the district, desirous
of promoting the establishment of the College; to draw up some plan for
carrying into effect the entire scheme, and to lay the result before a
special meeting of the Institute. In the meantime, he should be glad to
hear the observations of any member touching' the best mode of
establishing- the College in question.
Mr. Dunn enquired if an Act of Parliament could be obtained to enforce
the payment of so much per ton on coals for the support of the College 1
The President replied that such a mode had been hinted at, but it
would require serious discussion before such a scheme could be proposed.
Mr. Dunn said, only to raise a certain amount. A small tax would be
sufficient, because he thought it would not do to leave it to voluntary
contributions.
The President : What they required was, first of all. a sufficient sum
to erect the building-. They had laid before them a beautiful drawing of
a building for the purpose, and the first step was to raise sufficient
funds to erect the building; and then, he presumed, the requisite funds
for the payment of the salaries of the different Professors of the
College, and other current expences, would be provided by annual
subscriptions and by the charges made to the pupils.
Mr. Dunn: Yes, but if the principle of so much per ton were admitted,
they would at once succeed.
The President—The principle, however, had not been generally assented
to, as there were other interests to be consulted, viz., the
manufacturing as well as the coal trade. He also thought that the
Government ought to promote the object by giving a grant of money
towards the establishment, and he hoped towards the support of such a
College.
The Mayor of Newcastle begged to observe that at the last meeting-of the
Town Council, a report was presented from the Committee of Schools and
Charities, from which it appeared that a sum of £750 per Annum was at
the disposal of the Council for the purposes of education, but that sum
would ultimately reach £5000. Now, he could not say whether or not any
part of that money could be applied to the purposes of the Mining
College; but he must state that the report of the Committee recommended
the division of the £750 in a certain way without any
344
notice of the College at all. A few members of the Council, including
himself, said, that although the money in question ought to be strictly
applied to the purposes directed by the Charity, yet they thought the
Council might take a more extensive view of the matter, as in point of
fact there were many institutions established for the purposes of
education, which certain classes of society required, but which being
too expensive, were not within their grasp. Such classes, he thought,
were entitled to assistance out of the fund in question. Ultimately the
report was referred back to the Committee for further deliberation, and
on being presented the second time, he pledged himself to propose a
resolution in favour of the proposed College of Mining Engineers. He was
aware that the proposed College was intended principally for the Coal
Trade, and while he was willing for it to be so, yet he trusted that in
addition to the cultivation of those sciences so essential to Mining
Engineers, others would be taught, including geology, chemistry,
mathematics, meteorology, and other branches of philosophy, with the
object of advancing the education of gentlemen whose lives were devoted
to the manufacturing interests of the country. They must remember that
there were many important branches of industry in regard to which coal
itself was but the raw material, and he therefore trusted that the
College would be established on such a broad basis as would include the
great and important interests he had alluded to. With respect to the
propriety of incorporating the Mining College with any other, for the
purpose of embracing the entire kingdom? that, he thought, was a matter
for future consideration, yet, as an inhabitant of that town, and one
who had great confidence in the liberality of his fellow citizens, he
might venture to say that if it was determined to to fix upon Newcastle
as the site of the College, they might, if they could not obtain
extraneous and proper help, find the means within themselves. This he
considered quite possible when they looked at the great number of coal
and lead mines in the district, together with the iron and chemical
works: for it was almost impossible to produce another district in the
kingdom where all those branches of trade were so much concentrated, and
where a College, such as was projected, might be so easily supported.
Besides, he trusted that the Corporation of that town, which was bound
to watch over and foster such great interests, would come forward with
that aid which the importance of the subject deserved.
The President said that he agreed with everything* that had fallen from
the Mayor relative to the importance of the subject to the district
345
generally; and he felt confident that there were ample resources within
it to establish and support the proposed College. He begged, however, in
reply to the Mayor, to say that it had always been the intention of the
Council of the Institute to recommend, that the system of education
should be suitable for all the different branches of manufacturing
interests, that it should not be exclusively devoted to the mining
interest, but that it should include the education of pupils connected
with all the important trades alluded to. These principles he stated
were already set forth in the printed prospectus of the intended
College, and while he felt confident as to resources being obtained for
its support in the district, yet they still looked towards extending-
education in other parts of the kingdom. As to the nature of the
education to be given, this, as well as other details, will hereafter be
brought under the consideration of those gentlemen entrusted with its
establishment; but in the meantime he trusted that the Mayor, as well as
other influential gentlemen of Newcastle, including all connected with
the manufacturing and chemical interests would render their support in
conjunction with those belonging to mining- operations of the district,
to ensure the establishment of such a College as would do honour to the
district and confer benefit on future generations. When all these
important and varied interests were brought together, that would be the
most suitable time to go into the details of the course of education. In
conclusion,he submitted for theirconsideration, that the Council should
be instructed to draw up a statement to lay before the general meeting
in August, with a view to bring' the subject specially before the
Institute, in order that some plan might be devised as to the best
course to pursue to ensure success.
Mr. Dunn still was of opinion that they ought to adopt a sort of tonnage
both upon coal and iron, according to their relative value. If some
general principle of that sort was adopted, they could not fail to
succeed.
The President doubted that it was practicable to do this at present.
What they required at first was to raise a sufficient sum for the
building-, and next endeavour to obtain from the interests alluded to an
adequate annual subscription for its support. He was of opinion,
however, that if the College was once fairly established, it would, to a
very great extent, be self-supporting.
The Mayor had no doubt but that it would be self-supporting. For
instance the College in Edinburgh, with its 500 pupils, was
self-supporting.
The President—A subscription of between £30,000 and £40,000 towards the
erection of the building would at once set them a-going j
346
and then afterwards they might get annual contributions from gentlemen
connected with the coal and other trades to support the College for a
few years, until they ascertained whether it was self-supporting or not.
Mr. Boyd thought an application to Government for a sum of money towards
the building would not be out of place, especially when they knew that
the Edinburgh College was much beholden to the support of Government. A
sum of money, it was well known, was voted by Parliament in support of
that College.
The Mayor—Before applying to Parliament, they ought at least to raise
among themselves between £10,000 or £20,000, as that would be a strong
argument in their favour.
The President.—The Institution in Jermyn Street, London, which has been
established for mining education has received support from government,
not only towards its erection, but towards the salaries of the
professors attached to it. If, therefore, the government subscribed to
that institution, surely it could not refuse its support to so national
a project as the College in question. He thought it a disgrace to the
country that there was no such institution in it, especially when they
considered the immense importance of the mining interests in this
kingdom.
The Mayor believed that it was proposed to receive young men into the
College of a certain class, but he trusted they would not preclude any
whose businesses were dissimilar to mining, Sec.: for instance, he
should send his sons to the College to finish their education after
leaving school.
The President said there could be no objection to such an arrangement.
The Local Schools already alluded to, if established, might adopt such a
course of education as would prepare the pupils for the College, and
they would thus act as feeders.
Mr. Boyd observed, that in the Durham University there was a second-rate
course of education which was not charged high, while the pupils were
all eligible to the regular course of lectures.
The President, in conclusion, begged to submit the following resolution
for the adoption-of the meeting:—
" That the Council he instructed to cooperate with the Committee
appointed in London, and with other persons and bodies in the district
desirous of promoting- the establishment of the proposed College, and to
take such other steps as may appear to them best calculated to further
its establishment."
Mr. Dunn having seconded the motion, it was put and carried unanimously.
The meeting then broke up.
3-17
NOTES
OS
MR, J. J. ATKINSON'S PAPER,
ENTITIBD
"THEORY
OF THE
"VENTILATION OF MINES."
BY T. J. TAYLOR.
The subject matter of the foregoing paper is of so extended a character,
that, if dealt with in detail, a comment upon it would branch out into
numerous and laborious objects of investigation. The Notes I have made
are, therefore, either explanatory,or intended to illustrate the
practical bearings of various portions of the Memoir. I have also stated
where I differ from the Author in some cases; but after a careful
perusal of his paper, I cannot help expressing my opinion,
notwithstanding those differences, that it is a completer Precis of what
is known on the intricate topics of which it treats, than any other I
have yet seen; and that, without great pretensions to originality, it
will, at all events, form an excellent basis for those experimental
researches of which the subject so largely admits.
CHAPTER I.—No. 2.
Some experiments, to show the effects of local changes of temperature,
were tried, under my direction, in Backworth pit, with the following
results : Temperature at the upper station, 41 fathoms from surface, ..
55-8° F.
Ditto at the. lower station, 91 fathoms below the upper,...... 65-0° F,
Vol. III.—July, 1855* z z
348
Adopting- the usual law of the increasing density of air in descending',
we find that the density at the upper to that at the lower station is as
100,000 to 102,118; and, consequently, the relative volumes for the same
weight are cat. par. as 100,000 to ^'??6 = 9793°-
The expansion due to the difference of temperature is as (459 + 55'8 =)
514-8 : (459 + 65 = ) 524 :: 97930 : 99680 volumes; so that the air at
the extreme deep is still heavier than at the extreme rise,
notwithstanding the difference of temperature.
But another consideration remains, that of the hygrometric condition of
the air at each station ; in this experiment both very nearly approached
saturation ; and the enlargement of volume at 65° was, therefore,
greater than at 55*8.
The elastic force of watery vapour at 55*8° is '458
at 65° is -616 (Per Dalton's Table). Now, supposing the barometer at
the upper station to be 30 inches, it would be at the lower station (30
x 1-02118 = ) 30-64 nearly.
Therefore, the enlargement of volume at the upper station would be
100,000 x 8° tQ 458 =) 101527; and at the lower station
99680 x (8°,630^'616 = ) 101684.
The final result is, that, notwithstanding the difference of 91 fathoms
of level, yet, when all circumstances are taken into account, the
density is, in this experiment, less at the lower station than at the
upper one. The difference is indeed trifling, but sufficient to
establish the fact.
We are not to conclude that there was a more than normal temperature at
the lower station; both observations were made at levels much below the
plane of invariable heat, and the difference between the two stations is
nearly 9|° for 91 fathoms, being 57^ feet to a degree; which is less
than the usual rate of increase.
The necessity is thus perceived of entering upon a wide field of
observation and experiment in the collection of the data required to
form an accurate and comprehensive Theory of Mine Ventilation. And this
line of proceeding is the more imperative, because the ventilating
forces employed are in themselves very trifling, seldom exceeding three
or four inches of water column, and are, therefore, so much the more
easily influenced by the variable circumstances of different mines, or
even
349
of the same mine. In point of fact, the problem of the motion of
air-currents presents itself to mining engineers in a more complex form
than to others. We shall see more of this in the sequel.
CHAPTER I.—Nos. 3 and 4.
The rule that the velocity is equal to that of a body falling through
the height of the fluid, is applicable to the velocity in the vena
contracta. In the orifice the velocity is much less.
In an experiment from Rouse's Table we have the velocity of a wind put
at 47*66 per second; and the pressure on a square foot equal to 5-137
Bbs., but the height of column due to this velocity is ( 8^/47'66 =)
35-4 feet, the pressure of which is only 27 lbs; so that nearly double
the height due to the velocity is required to give the pressure. In an
experiment of Girard's, the velocity of air issuing from a gasometer of
sheet iron 1-13th of an inch thick, under 1*33 inch of water = 90 feet
of air (l-33 x 812) 55"2 feet per second. Now, the height due to this
velocity is 47'7 feet, or about the half the entire column.
CHAPTER I.—-Ms. 5, 6, 7, and 8.
Another condition should in strictness be added, that of the density of
the propelled fluid.
The pressure (or resistance) is directly :—
1.—As the surface, that is as the perimeter x length. 2.—As the square
of the velocity.
3.—As the density, which is not, however, included by the Author. The
resistance is also inversely as the area; that is,,as the number of
particles amongst which the aggregate resistance is distributed.
And thus the resistance arising from the motion of air or gas in any
channel is determinable by the expression,
Length x perimeter x velocity squared x density
area. CHAPTER I.—No. 10.
There is some obscurity in this which, can, perhaps, be explained away.
The absolute amount of pressure is not, in fact, equal for all gases,
but is, ccet. paribus, greater for the gas of greater density.
350
The experiments of Girard, here alluded to, give the same constant of
pressure, but in this case the motive agent is represented in gas of the
same density with that which is propelled; so that the gas of least
density requires also the least pressure.
IF A
For example, the expression 74,^/ gives the velocity in cast
iron
pipes from Girard's experiments, where H is the pressure-column, A the
area, L the length, and P the perimeter; but in this ease H is always in
the denomination of the gas itself; if we retain H in air column
77" A
then the expression becomes 74^/ t ..- where 2 is the density of the
gas, that of air being 1.
CHAPTER I.—No. 11.
The resistance diminishes as the density diminishes, and vice versa.
When the barometer falls, the ventilating column is lessened in weight,
but the resistance in the mine is also lessened.
The volume of air in circulation is therefore, (considered per se), the
same; but being in some degree lighter, its efficiency as a ventilating
agent is not so great as before, while the issue of gas from the mine is
greater, and replaces a part of the air-current. In the course of my own
experiments, I have found the volume of air greatly reduced by very high
winds, not by variations of barometric pressure.
CHAPTER I.—No. ia
Effect of Benbs.—Bends or angles at a distance from the point of
greatest pressure have a less effect than those nearer to it; and if the
bends are so made as to cause an elevation in the general level of the
main, their effect may be, as I shall afterwards explain, not merely
nil, but actually favourable to an increased current. Baubuisson's and
Peclet's apparent results may be probaby accounted for on these grounds.
Clegg (gas-lighting) tried some experiments of this kind with the
following results:—
Difference.
A 2-inch pipe, perfectly horizontal, and 30 feet long, delivered
2898 cubic feet of gas............................ —
------------------with a semicircular bend, at 15 feet, it delivered
2754: cubic feet of gas............................ ¦£$
351
Differenc*.
A 2-inch pipe, with a quadrantal bend, it delivered 2834 cubic
feet of gas...................................... -^
------------------with a rectang'ular bend, it delivered 2824
cubic feet of gas................................ ¦£$
He observes that u two semicircular bends make twice the difference ;
three bends make thrice the difference; that a semicircular and a
rectangular bend form an obstruction equal to the sum of the two, or ^ +
-fa, and this seems to be the same under all variations of
circumstances."
But it is clear that in a larger channel the effect of bends is much
diminished: for example, supposing the velocities and other
circumstances to be the same, with a variation only in the diameter of
the pipe, and if the smaller pipe be 2 inches and the larger 8 inches in
diameter,
., ,-, , ,. ... 2 representing the
perimeters K ,
then the relative positions are, as------f---------a.-----jl----------=
•& to
x 4 representing the area
8 representing the perimeter = ,m which ig ^ ft fowth of ^ f
64 representing the area and as the quantity in the large pipe is 16
times greater, it is found (if we adopt this view) that the effect of a
rectangular bend in a 6 inch pipe is, that of subtracting (£ of -^ of
T^) =-pjg^ of the volume which would have passed through a straight
horizontal pipe.
We may therefore conclude, thus far, that the effect of bends in large
air channels, such as those of mines, is not material. On the contrary,
it is easy to conceive that at very high velocities, such as those
generated by pit explosions, the effect of bends must be very great.
END OF CHAPTER II.
The resistance of fluids in motion is, in fact, a term of so great
importance, that in extended channels the conservation of force to which
the final velocity is due is comparatively insignificant. In a mine, the
height of whose ventilating column is 144 feet, the theoretical velocity
is (8 s/ 144 = ) 96 feet per second, whereas the actual mean velocity
may not exceed 4 feet per second; but the height due to 4 feet in a
second is only -25 feet of column, being the l-576th part of the actual
column employed in this particular example.
CHAPTER III.—No. 17.
In reference to the question of the " gravitation of the air in the
descending and ascending parts of the mine," see further on.
352 CHAPTER III.—Ho. 19.
The resistance is due to the expansion L P V':%. (See ante, p. 349.)
CHAPTER III.—No. 21.
The investigation of the motion and resistance of horizontal currents is
not, however, sufficient to meet the whole question.
CHAPTER III.—No. 24.—-Ventilating Column.
We have no analysis of such admixtures of air, gases, watery vapour, &c,
as occur in mines, and in the upcast shafts of mines, and can only,
therefore, approximate to their actual constitution. The following-
remarks may, at all events, help to show the extent and nature of the
alterations in question, and whether they can be neglected without
material error, as directly affecting the ventilating column. We are to
consider:—
1. The alteration caused by changes of temperature and of hygro-
metric condition in the volume and density of the air.
2. The effect of extraneous products upon the return current, whether
those products be derived from the gases of the mine or from
respiration.
3. The effects of the products of combustion, when a part of the
return air is decomposed by passing over a furnace.
4. The effect, which I shall here regard as a special one, of intro-
ducing steam into a shaft. In following out the investigation I shall
take an actual case, where the mean temperature of the upcast shaft was
105° Pahr., the quantity of air which entered the downcast pit was
30,312 cubic feet per minute, and the quantity of coals consumed by the
underground furnace was 3-11 lbs. per minute.*
* In the calculations which follow, I have not introduced the mean
temperature of the downcast air, as an element; the object being- simply
to make certain terms of comparison between air at 32° entering- a mine,
and the same air issuing-, as modified by the complex circumstances to
which it has been subjected in passing- through the mine and the upcast
shaft.
I have adhered to the rate of expansion stated by Gay-Lussac, namely,
the ^ part for each degree ol Fahrenheit above 32°, the calculations
having- been made previously to Reg-nault's more recent investigations,
establishing- 3Sl, or rather 39\.5> as a more accurate measure of
expansion above 32'-'' Ph. = ?|5 from Fahrenheit's zero. The relative
results are not altered by the difference between the two.
353
Now, if no other alteration were to take place in the entering air
excepting that due to expansion by heat, we could very easily determine
the relative volumes at 32° and at 105° to be 30,312 and 34,922
respectively, and the relative densities to be as 1 to '8680.
But the other influencing- circumstances, of which mention has been
made, must also be considered; and first, as to changes in the
hygro-metric state of the air.
The temperature of the air at the surface was 32°; the wet bulb of
Mason's hygrometer was 31!°; the atmosphere was, therefore, very nearly
saturated with vapour. In the air current of the mine, before it passed
over the furnace, both thermometers stood at 53°, again showing a
saturated state of the atmosphere. And here occur the two first terms of
our enquiry.
The expansion of air by the difference of temperature from 32° to 53°,
being 21°, allowing 1-480 part of expansion for each degree above 32°,
is gs 480 to (480 + 21=) 501, or as 1,000,000 to 1,043,750, and multiply
by 30,313, we have the enlarged volume of air at 53°, equal to 31,648.
Then for the expansion by moisture at 53° compared with 32°, the volumes
being as the sums of the elasticities of air arid vapour respectively,
we have,
Inches.
Elasticity of vapour at 32°____.................. 0-200
Standard height of barometer.................... 30*
30200
And Elasticity of vapour at 53°.................. 0-415
Standard height, as before...................... 30"
30-415
Ratios of volume 30-200 to 30-415, or 1,000,000 to 1,007,119, which,
multiplied by 31,638 gives 31,863 as the resulting volume when corrected
for the temperature and hygrometric state of the mine.
A spontaneous ventilation is capable of being excited by a difference
merely in the hygrometric states of the entering and issuing air
currents, such difference amounting sometimes to one equivalent to that
which would be produced by several degrees of temperature j if dry air
entered a mine at a certain temperature, and issued even at the same
temperature, but saturated, the issuing volume would be a good deal
lighter than the entering one.
354
We may next consider the product of respiration. A man produces very
nearly a cubic foot of carbonic acid gas in an hour, and to form the
carbonic acid abstracts the same volume of oxygen from the atmosphere.
And if we assume for the example taken, that 300 persons are employed,
an extra number being computed to allow for horses, candles, and lamps,
then the carbonic acid produced by them is only 300 cubic feet in an
hour, or 5 cubic feet per minute, representing 25 feet of atmospheric
air, viz:—
Cubic Feet.
Carbonic acid gas replacing the oxygen,........ 5
Nitrogen,................................ 20
25
(Also vapour from the lungs 6 grains per minute, from each man;
insensible transpiration from the lungs 20 grains per minute, from each
man j in all 26 grains per minute = 4J lbs. troy, in 24 hours, but these
products are too small to affect the general result.)
As regards the gaseous products of the mine; in the absence of correct
information we must take them at something which may be regarded as an
extreme, and with this object in view, I shall assume that an addition
of -fa part is made to the volume already found, by the light
carburetted hydrogen that issues in the mine. I need scarcely remark
that this proportion very greatly exceeds what is generally met with,
but the result is, in some measure, qualified by the circumstance that,
if on one side the volume and consequent velocity be increased, the
density is on the other diminished.
As regards the product of combustion. Supposing 1 lb. of coal to require
2T6^fcs. of oxygen for combustion, then 3*11 lbs., of coal will require
8*09 lbs. of oxygen. Some theory enters into the consideration of the
products of the combustion of coal, but allowing the oxygen of the coal
to form watery vapour with a portion of its hydrogen; and the nitrogen
of the coal to form ammonia with another portion of hydrogen; the
sulphur of the pyrites to leave in the shape of sulphuretted hydrogen,
we shall then have the following products of combustion by weight: —
Watery vapour,.................. 1'45 lbs.
Ammonia,.......................0-07 „
Sulphuretted hydrogen,............ 0*04 „
Carbonic acid, .................... 9'64 „
11-20 fes.
355
(Coal,.............. 3-0
Oxygen,............ 8-09
11-20)
The first three ingredients are too minute in quantity appreciably to
effect the result, and I shall, therefore, leave them unnoticed. The
carbonic acid represents a volume which, at the temperature of the mine,
would be 95 cubic feet.
We can now classify the several ingredients as follows :—
Density.
Air entering the mine,.......................... 30,312 .. 1,000
The same for expansion to the temperature of the mine
more, ................................... 1,326
The same for the difference between the hygrometric
state of the mine, and that of the atmosphere, more, 225
31,863
Deduct air of respiration, ................ 25
Do. air required for combustion,.............. 476
------- 501
31,362 .. -970
Add light carburetted hydrogen, which appears to be always mixed with
other gases, as olefiant gas and nitrogen; specific gravity say 0*600,
.... Density. 784
Add carbonic acid gas from respiration, 5 .. 1'548
Do. from combustion, ............ 95 .. 1-548
------- 100
Add nitrogen from respiration, .... 20 .. -986
Do, from combustion, ............... 381 .. -980
------- 401
32,647
In cases of ordinary combustion, a quantity of combustible matter
escapes without being burned, a part of it appearing in the shape of
smoke or soot. The carbonaceous particles which thus escape, however,
easily float in air, owing to their minute division, and if converted
into invisible carbonic acid by union with oxygen, act more in
retardation of the current. By assuming them to be converted into
carbonic acid gas (as in the calculation), a greater allowance is really
therefore made than is due to them in an uncompounded state. In fact,
the whole quantity Vol. III.—July, 1855.
a a a
356
of coal consumed is only 3-11 lbs. per minute, and assuming- 2| lbs. to
consist of carbon, and one-half of this to escape combustion, the
quantity so escaping* combustion becomes 1| lb. per minute.
Now, we shall see immediately that the aggregate quantity of air and
other gases passing* through the upcast shaft is 36,035 cubic feet, and
that the common density of the mass is *8724.
The weight of a cubic foot of such mixed gases, at this density, is
¦0706 lbs., therefore the weight of 36,035 cubic feet is 2544 Bs. It is,
therefore, manifest that the unconsumed carbon, being on the data
assumed less than the Tifcru part of the weight of the entire volume can
have no appreciable effect on the calculation.
We have next to calculate the densities, assuming that of the entering
air to be 1. The rest are corrected to 53°.
Volumes.
31,362 Air in mine at -970,.......................... 30,421
784 Carburetted hydrogen at -600,.................. 470*4
100 Carbonic acid at 1*548,........................ 154*8
401 Nitrogen at *986,............................ 395*4
32,647
31,441*6
Mean density Sl'^}'^ = .................. -9630
J 32,647
Expansion of volume 32,647 from 53° to 105°.
480 + 21 = 501
480 + 73 = 553
As 501 : 553 :: 32,647 : 36,035.
Ultimate mean density in shaft........ '9630 x ^' 0> —" *8724,
J 36,035
The results are therefore :—
Volume of air entering the mine,........................ 30*312
Volume of air and mixed gases in the upcast shaft,........ 36 035
Density of air entering the mine, ...................... 1*
Density of air and mixed gases at mean temperature of upcast,
0*8724
Relative velocities of cold and heated volumes, supposing them to move
36 035 in channels of same sectional area, 1 to ' ¦ =:
1*18880.
oU,o *<o
Relative squares of same velocities, 1 to 1*4132.
And the density being 1 to *8724, and all other circumstances alike,,
the
relative resistance is as 1 to (-8724 x 1-4132 =) 1*2329.
357
If, with a view to those mines which yield carbonic acid gas, and not
fire-damp, we assume the fire-damp to be replaced, in the example, by
784 volumes of the former, which is a larger aggregate quantity (l-40th)
than we may expect to meet with in practice, then the statement in page
356 will stand as follows:—
Volumes.
31,362 of air in mines at *970 density............ 30,421
784 carbonic acid at 1*545 .................. 1,214
100 do, as before................. 154*8
401 nitrogen ... ?.......................... 395*4
32,647
32,185*2
Mean density ................3f^5'2 = -9858
J 32,647
Expansion from 53° to 105°, as before, 32,647 to 36,035.
Ultimate mean density in shaft, *9858 x T^f = '8931. J '
36,035
The relative resistances are, therefore, in this case, as 1 to (*8931 x
1*4132 =) 1*2621.
We have thus seen how the ventilating column is affected by the gaseous
products of the mine and of combustion, namely,
Weight of Weight of
Downcast Upcast Difference.
Column. Column.
1. Pure air........................10,000... .8680.. ..1320
2. Altered air, with carburetted hydrogen 10,000___8724___1276
3. Altered air, with carbonic acid......10,000___8931___1069
The numbers in the second column are the densities, as already found.
If, then, the motive column in the case of pure air be 132 feet, it is
reduced in the second case to 127*6 feet, and in the third to 106*9
feet; and the velocities or quantities will be, cent, par,, as the
square roots of those numbers, viz.:—
V 132 = 115 or 100.
V 127*6 = 11*30 or 98-3.
V 106-9 = 10*34 or 90*0.
In other words, where mines with furnace ventilation yield carburetted
hydrogen gas, the result due to the uncorrected ventilating column must
98-3 be multiplied by -^Tut) anc* where carbonic acid gas is the
principal
90 gaseous product of the mine, then that result must be multiplied hj —
358
The question of the proper relative size of downcast and upcast shafts
is capable of being illustrated from the foregoing considerations,
limiting our investigations for the present to the postulate, that the
resistances of the two shafts shall he equal, one of them being for this
purpose varied in size, if found requisite to do so. I shall assume that
the shafts are of equal depth: if otherwise, the expression for length
can easily be introduced : and that the diameter of the downcast shaft
is 10 feet; we are then to determine the proper diameter of the upcast
as deduced from the data already furnished.
We have seen that in the first case put the relative resistances in the
two shafts are as 1 to 1-2329: and to equalize this resistance, which is
the object of investigation, we are to increase the size in the upcast
in a
certain definite proportion. But this proportion is not a simple one?
having reference to the numbers given. On the contrary, it is clear
that
if the diameter of the upcast be increased, then the other conditions of
resistance are affected at the same time. The area for example,
augments
as the square of the diameter; the velocity diminishes in a similar
ratio ;
and the resistance, again, diminishes as the square of the velocity.
On
the other side, an increased diameter enlarges the surface of contact;
so
that by arranging the whole of these terms, we ultimately arrive at the
following equation, expressing the ratio, namely:—
Z>2 x D* x Z>2 2>6
---------_-------- = - = ^t0^
And the ratios of the diameters thus become
As 1 : 1-2329 :: (D5 =) 100,000 : (B's=) 123290 Where D and B' are
the respective diameters.
Then for </ D' the log. of 123290 is 5-0909279 H- 5 = 1-0181856, the
natural number of which is 10*426 feet, which is the proper relative
diameter of the upcast; equal to 10 ft. 5 in.; that of the downcast
being 10 feet.
Summary of comparative results :—
Diameter. Area. Velocity of
Current.
Feet. Ins, Sq. Feet. Feet per
Second.
Downcast...... 10 0 ...... 78-54 ...... 6-43
Upcast........ 10 5 ...... 85-37 ...... 7-035
Increase in upcast 0 5 6-83
-605
In the foregoing investigation, it is clear that we may substitute the
squares of the volumes, for the volumes x squares of velocities: since
359
the velocities and volumes increase, cceteris paribus, in the same
ratio. Then we have :—
Velocity. Density.
Square of 30,312 x 1 = 918,817,344.
Square of 36,035 x '8724 = 1,132,829,916.
Proportional resistance 1 to 1-233 nearly as before.
Or if q be the volume in the downcast assumed to be 1.
d the density in the downcast also assumed to be 1.
q' the ratio of the volume in the upcast.
dl the ratio of the density in the upcast.
q'% d' Then the ratios of the diameters should be as 1 to fy *—— ; but
q% d
q* d
is = 1: therefore the ratios are as 1 to ^/(q'z d') : or as 1 to the
natural number of °°'-f-----
5
It has been argued that upcast shafts should be made of a section much
larger at the bottom than at the top; and the cone of a glasshouse, or
the still more disproportionate structure of a dome, have been adduced
as types of a more scientific form of shaft than the one we are in the
habit of employing. We are now enabled to test the value of this
principle by applying to it the foregoing formula.
Supposing the current of the same shaft which has furnished the example
to have a temperature at the bottom of 160° F., which is 55° higher than
its mean temperature, then the question is, what ought to be its
diameter at the bottom, to equalize, as before, the resistances of the
two shafts as regards this particular point of comparison.
We have seen that the air entering the downcast, expanded in the mine
from 30,312 volumes to 32,647 volumes, and that its density under these
circumstances was -9630.
Then for the expansion from 53° to 160°:—
480 ................ 480
21 ............... 128
501 608
As 501 : 608 :: 32,647 : 39,619 volume in upcast. Ratio of volumes
30,212 to 39,619, 1 to 1-30704.
•9630 x qHTTTq = -7935 density in upcast.
Then q* d! = 1-3073 x 7935 = 1-708 x -7935 = 1-3553. The Log. of
which is -1310354 -~ 5 - -0262071 whose natural
3G0
number is 10-622 = 10 feet 7\ inches, the required size of upcast shaft,
being- an increase of 7| inches only in the diameter of the downcast.*
We shall now put the special case of a large admixture of steam with the
current of the upcast.
Supposing- the entering air to be in this case 60,000 cubic feet per
minute, and the temperature to be 149°, then the volume of air and mixed
gases before passing over the fires will be 64,622, and the mean density
'9630 on the data already given.
But as the temperature in the upcast is higher, the expansion will be
proportionably greater, viz. :—
480 480
21 117
As ------ : ------ :: 64622 : 77,004
501 597
Whence we have the mean density in shaft
= -9630 x |^2| = ,8081
4 steam boilers consuming coals at the rate of 3 tons per day each,
require 18§Bbs. of coal per minute, and supposing 73fos. of water to be
evaporated by each pound of coal, this gives 130§Ibs. of steam per
minute, equal to 914,666§ grains of steam per minute, and this
distributed amongst 77,004 cubic feet per minute of air volume in the
shaft gives 11-87 grains to a cubic foot.
By Dalton's Table we find that this quantity is computed to saturate a
cubic foot (not at 149° but) at 82°,
Therefore the enlargement of volume by the admixture of the steam is as
follows:—
Elasticity of vapour at 53°.................. 0-415
Standard..................................80-
30-415
Elasticity of vapour at 82°.................. 1-07
Standard...................................30-
31-07
* The upcast should, therefore, in the case put, be practically, a
uniform cylinder of about 10 feet 6 inches in diameter, the diameter of
the downcast being- 10 feet.
I do not here attempt to exhaust the subject of the proper relative size
of downcast and upcast shafts ,• in reality, the sectional area of an
upcast shaft has, in furnace ventilation, a material influence upon its
temperature, that is, upon its power; its resistance is, therefore, only
one part of the question.
361 Then as 30-415 ; 31-07 :: 77004 : 78,662
And the ultimate mean density is, 7 .oaoi 77,004___.
(allowing for expansion of vapour) } ' 78,662
It thus appears that the increased volume in the upcast, occasioned by
the discharged steam, is no more than about the ^ Par^ a difference not
practically appreciable, especially when it is considered that the small
increase of velocity, and, consequently, of resistance thus arising is
met partly by the diminished density due to the same cause.
It is evident from the foregoing considerations that the steam does not
condense in the upcast, because there is not enough of it to saturate
the volume of air with which it is mixed.
And as the steam retains its state of vapour, its latent heat is not
given out during its passage through the shaft.*
If the air at 149° had been saturated with vapour, then the volume and
density would have been as follows :—
Elasticity at 53° ...... 0-415
Standard ............ 30-
30-415
Elasticity at 149°...... 7-23
Standard ............30-
37-23
As 30-415 : 37-23 :: 77,004 ; 94,258. Density allowing- for expansion
by
77 004 Vapour -8081 x 9f<m ~ "6602
But to saturate a cubic foot of air at 149° requires 45-7 grains of
vapour.- therefore, 4 times the number of steam boilers would have been
required for saturation.
CHAPTER III.—No. 25.
In estimating the pressure required to generate the final velocity, that
velocity must not be regarded as the one existent at the top of the
upcast
* The same quantity (by weight) of vapour, contains the same quantity
of heat, whatever be the temperature of the vapour.
362
shaft, but as a mean velocity due to the passage of the air through an
aggregate of channels, of which the upcast and downcast shafts are
portions. The issue at the mouth of the upcast shaft is due to the
momentum of the entire column; if reduced in area at the top the
velocity would be increased, and we should then appear, on the principle
advanced by the author, to have, a greater residuum of force, whereas it
is obvious that there would really be a less one, quoad the additional
resistance created by such contraction. I have closed 2-3rds of the area
of an upcast shaft at the top, in the middle, and near the bottom (by
means of a cradle), without causing a sensible difference in the
quantity of air circulating in the mine; in this case, therefore, the
velocity of issue at the top of the shaft would be trebled, yet the
force establishing that velocity was obviously not greater, but
manifestly less than with the uncontracted shaft, for the reason above
given. *
Again, supposing the upcast shaft to be, not contracted, but enlarged,
such enlargement would cause a diminution of the velocity of issue, and
would, therefore, according to the author's view, exhibit a less
residuum of force generating the velocity. Yet it is evident that no
such diminution has occurred, but, on the contrary, an increase of the
remainder force, owing to the reduced resistance due to the lower
velocity.
The ventilating column of Hetton Colliery, in the case cited, is 900 x
167*5
___ = 300 feet of air at 211°. The velocity in the upcast shaft I
make, by calculation, 32 feet per second, and the column due to this
velocity is 16 feet, or in cold air the height of column is 13*6 feet,
as given. But the mean velocity, which ought to be the basis of
calculation, is, (though not given) probably no more than 4 or 5 feet
per second; and if the last of those numbers, then the height of column
due to it is '39 foot, which, instead of the l-16th part of the
ventilating pressure, is no more than the l-577th part of it.
Similar remarks are applicable to Tyne Main and Haswell examples. In the
case of Tyne Main there is not l-8th, but really less than l-500th of
the ventilating power employed in generating the ultimate velocity.
CHAPTER IV.—Nos. 30 and 31. Here, again, we feel the want of
experiments, enabling us to fix with
* In the case cited, the velocity of the upcast current, in the full
sectional area of the shaft, was not more than 13 feet per second.
363
precision the laws of the lowering of temperature in upcast shafts.
There is a tendency to establish a minimum temperature in the upper
portions of those shafts, which it will be very difficult to blend with
a general law applicable to their entire development. The cause of this
tendency resides in the circumstance, that a heat which is not of itself
considerable, compared with the usual atmospheric temperature, when
communicated to the walls or sides of the shafts, is retained by those
walls; and the temperature of the air-current, being influenced by it,
does not, therefore, continue to diminish, on reaching this part of the
shaft, according to the same law which prevails elsewhere. In some cases
I have found very little variation in the temperature of the upper 40 or
50 fathoms of the air-current in upcast shafts,
CHAPTER IV.—Page 110.
It is not requisite to have the dimensions of the upcast shaft given to
ascertain the horse's power exercised in furnace ventilation: the
height
of ventilating column, the quantity of air discharged, and the weight of
a cubic foot of air, are alone required for this purpose. For
example,
the height of column in the Haswell case is 154*5 feet, the quantity of
air is 94,900 cubic feet per minute, and the weight of a cubic foot of
air
at 62° is -0767 lbs.
94,900 x -0767 x 154-5 Q, nQ , Then, —-------33~000----------=
e Power-
CHAPTER IV.—Page 112.
The question between furnace and engine ventilation requires much
further research. The simplicity of the furnace, and its constancy of
operation, are greatly in its favour j but its mechanical results are
not relatively advantageous, and it is probable that, if the method of
splitting the air had not been introduced, we should long ago have been
obliged to supersede the furnace by mechanical agents of ventilation. I
shall here make a comparison between the useful results of furnace and
mechanical ventilation. The case taken is one from my own notes—that of
Seghill Colliery, where there was not an underground steam engine, as in
the case of Haswell, and where the result, as an example of furnace
ventilation, is above the average relatively with the fuel consumed; the
quantity of air being 42,708 cubic feet per minute, the coals consumed
Vol. Ill,—July, 1855. bbb
364
470 lbs. per minute, the mean temperature of the upcast 122°, and the
ventilating- column 65*3 feet, equal to almost exactly 5 lbs. on a
square foot, The horse power is, therefore,
42708 x 5 _ f>47 33,000 ~0^-Now, allowing, as the author has done, 12
lbs. of coal per hour per
horse power, (which is too much,) we have-----^----- = 1*294 lbs. of
coal per minute, due to the useful effect, which is in this case,
therefore,
1*294 only ¦ = 27*5 per cent, of the gross power in operation.
I am informed, by Mr. Samuel Dobson, of Treeforest, Glamorganshire,
that a Struve's Ventilating Machine, at the Middle Duffryn Colliery,
did its work very well ; and that the aggregate quantity of air, as
found
by experiment, in circulation through the mine channels, was quite equal
to 5-6ths of the calculated quantity due to the machine, as deduced from
the area of the cylinders and the number of strokes in a given time.
It
further appears, that the pressure required to open the valves of the
machine was equal to 5-20ths of an inch of water, or 1*28lbs. on a
square
foot. * Considering, then, this machine to be applied under
circumstances
similar to those of the furnace already calculated, we have,
$40,708 x (5+ 1-28=) 6-28 _ 321,850 _ ^ h
3p00---------------3p00 ~ J ^ h0rse V°Wer>
9*75 x 12
and-----^-----= 1-95 lbs. of coal per minute, instead of 470, the
oO
furnace consumption.
Then, t^ = 66-3 per cent, of useful effect. 1*95
This inferior result with the furnace, as compared with the steam
ventilating machine, is not perhaps difficult to be accounted for.
Viewing the upcast shaft as a machine, the energy of which depends upon
the temperature of the contained air, it is clear that the structure of
the shaft is unfavourable to the conservation of that temperature, on
account of
* This machine is the largest of the kind which has yet been erected—it
has two 20-feet cylinders, and a double action; stroke may be made 4, 6,
or 8 feet. With one cylinder at work it was driven twelve strokes per
minute, 6-feet stroke. The estimated duty is, in this case, 45,200 cubic
feet per minute, and the quantity actually in circulation in the mine
was 38,000 to 39,000 cubic feet per minute. With two cylinders and 8£
strokes, the estimated quantity is 64,000 cubic feet; the actual
quantity was 55,000 to 56,000 cubic feet.
•365
the distance of its upper portions from the heating agency, and the
absence of any means or appliance to maintain the original heat. It thus
happens that the useful effect is governed more by what takes place in
the shaft than by the original quantity of heat produced.
To augment the quantity of air multiplies the disadvantages of the
furnace. Supposing that it were wished to double the quantity, we should
then require eight times the fuel, or, in the case cited, 37*6 lbs. per
minute, all other circumstances being the same. With machinery we should
also require eight times the power, because the double velocity takes
four times the power, and the moving power would also itself have to
increase its velocity to twice the former rate; but this octuple ratio
is attained at an expense of (1*95 x 8 =) 15*6 lbs., so that the
comparison would stand as follows:—
Volume of Air. Fuel, with Furnace. Fuel,
with Machine. Difference.
ffis. lbs.
lbs.
1................ 47 ........ 1-95 ........ 275
2 ................37-6........ 15-60........22-00
Increase, lbs. per min. 32*9 13*65
The furnace system has, in fact, been maintained by reducing the
resistance; in other words, by carrying the splitting of the air to an
extent of subdivision which, in some cases, can hardly be considered
safe.
CHAPTER V.
Some years ago, Mr. J. Taylor made, at my request, upwards of one
hundred observations at Haswell Colliery of the quantities of air
circulating in the several splits (then eleven in number), with the
areas and velocities at each point of observation. At that period the
total quantity of air was 65,641 cubic feet; the mean temperature of the
upcast was 109°; the ventilating column was 1037 feet; the pressure
8162lbs. on a square foot, of which 4*92 lbs. were employed in
ventilating the mine, and 3*24 lbs. in overcoming the resistance of the
shafts.
Subsequently the quantity of air was increased to 94,900 cubic feet per
minute; the ventilating column being 154*5 feet: the pressure on a
square foot 11*90 lbs., of which 2*94 lbs. was employed in ventilating
the mine, and 8*96 lbs. in overcoming the resistance of the shafts,
including that of the short channels between the shafts and shaft doors.
The resistance of the mine channels was, therefore, less with the larger
quantity of air than with the smaller one; the reason of which was, that
366
in the interim the number of splits had been increased from 11 to 18.
But the resistance in the shafts had, as a consequence of the increased
volume of air, become much greater, and indeed absorbed not less than
751 per cent, of the entire motive column. It is right to remark, that
the size of the upcast shaft had, in the meantime, been partially
reduced by casing the tubbing.
The enlargement of shafts, of which this result is at once suggestive,
is not, however, to be regarded as a simple question. With an equal
quantity of fuel, we cannot, ccet. par., have the same temperature in a
shaft of large area as in a smaller one, because the cooling power of
the
a shaft depends greatly upon the expression-^ ; if, then, the advantage
gained by diminishing the shaft resistance be not commensurate with the
disadvantage of the loss of motive column, or the necessity of using a
greater quantity of fuel to make good that loss, we may lose and not
gain by increasing the size of an upcast shaft j it follows, therefore,
that there is a maximum size of shaft, having relation to the
development of the mine channels, beyond which we should find the
quantity of air per lb. of coal diminishing and not increasing. These
remarks apply to furnace ventilation only; where machinery is employed,
it is obvious that the larger the size of the shafts the greater is the
useful result.
From the Haswell experiments, above referred to, I deduced the following
theorem:—
TT A F=5111 vf-^
"Where V is the velocity in feet per second.
H the height of ventilating column in air at 60°.
A the area or cross-section of air channel (or sums of the areas
of the several channels). L the length of channel.
P the perimeter of channel (or sums of the perimeters of the several
channels.)
(Dimensions in feet.) A theorem, from experiments by Mr. George
Greenwell, at Crook Bank Colliery, differed from the foregoing. It
was,
TT A
V = 38-33 V ^-J
Peclet's theorem for brick chimneys, when reduced to the same terms, is>
TT A
V = 36-01 V ±±4>
CHAPTER VI.—No. 58.
Ventilation of Deep and Rise Workings.
I found, in some experiments on this subject at Earsdon Colliery, that
when the deep-way was shut off, the loss of air was nearly one-half (46
per cent.) of the entire volume in circulation, with both rise and
deep-way open; but when the contrary course was adopted—that of shutting
off the rise-way, and keeping the deep-way open—the loss was only l-6th
(17 per cent.) of the entire volume in question. The air-channels in
each way were very similar, both in length and in other respects; the
inclination in the deep workings (towards the 90 fathom dike) averaged 1
in 6; in the rise-workings it was much less, being about 1 in 12.
The greater comparative facility with which deep workings are
ventilated, is not, it is submitted, to be accounted for on a principle
of gravitation. Setting aside considerations of temperature, variation,
and other extraneous conditions, the weight of column below the level of
the upcast is balanced by its return column up to that level. In the
opposite case, if an ascending column of air be regarded as reacting
against the ventilating power, its corresponding return column operates
in favour of that power, and again neutralises the action. The
barometric pressure doubt-less alters with every step in an ascending or
descending direction; but the mean result of all the heights in the
ingate is equal to the mean result of all the heights in the return,
considered with a view to gravitation alone.
There is another circumstance in which, I apprehend, a solution of the
matter will be found to reside.
If a barometer be earned from the bottom of a downcast shaft, upon the
same plane, through the ingate and return air-courses, it will be found
constantly to Jail in receding from the downcast and approaching the
upcast. The difference in height represents, in fact, the pressure
employed or absorbed in ventilating the mine from the bottom of the
downcast to the point of observation, whether the latter be at the
upcast shaft, or at any intermediate part of the air-course.*
* Of course a water-guage gives a similar result. I have made use of
shaft doors and also of in-bye doors to determine the differences of
pressure, allowing for the friction of the doors, as determined by
experiment. A well-constructed door is, in fact, a pressure-guage, whose
accuracy is proportional to its area: an error, if any exist in the
experiment, being of relatively minor consequence when spread over so
large a surface.
We have in this case supposed the barometer to be carried upon a water
level line: but it is obvious that the same cause and its
corresponding-effect are in operation on ascending" and descending-
planes, though the variations of the barometer due to simple differences
of level render it in the latter cases less easy of detection.
The result then, is, that the entering air (starting from the bottom of
the downcast) is in a state of greater compression than the issuing air;
and as a direct conclusion, that the air in the ingates is, owing to the
cause assigned, and all other circumstances being alike, heavier or
denser t han the air in the returns.
The consequences of this difference may be more clearly appreciated by
supposing the return column to consist of a gas a little lighter than
atmospheric air, or of a mixture of atmospheric air, and
sub-car-buretted hydrogen gas: and we shall then perceive that the
lighter column ascends from the deep workings upon the same principle,
in fact, that light or rarefied air ascends a shaft: but in the rise
workings the operation is reversed: the lighter column if the return is
to he forced downwards, and these cause a loss of motive column equal to
the mechanical effort required for this purpose. It will be observed
that in carrying out the comparison the result is doubly in favor of
deep workings; for a positive addition is made to the power by which
they are ventilated by the cause under consideration; while by the same
cause an abstraction is made from the power ventilating the rise
workings. The difference, therefore, is not measured by a simple
expression (n) but by (n -{- n') where n is the ascensional force
assisting the return of the deep air, and n' that retarding the return
of the rise air.
I regret to differ from the author in my explication of this curious
subject. Much stress is laid by him upon the supposed insignificance of
the forces thus brought into operation; but those forces are in reality
far from being insignificant, relatively with the ventilating powers
employed, which is of course the only correct standard of comparison.
For example: supposing the ventilating column to be equal to 4 inches
of water, of which 1 inch is employed in occasioning the resistance of
the
upcast; then at a medium distance from the downcast we shall have a
residual pressure of 2| inches, and the mean compression operating upon
4 + 2h the entering air is —h— = 3| inches; while the mean
compression
gi i J operating upon the return air is -—^— = 175 inch. The
difference
between the two is T50 of an inch.
369
Now, it is true, that this inch-and-a-half of water column cannot affect
more than about the ¦%%-$ part of alteration in the density of the
atmosphere ; but it is not the density of the atmosphere which is the
subject of comparison, the real question is, what proportion the little
water column of 1J inch bears to the ventilating column of the mine; for
just so much of that ventilating column must be employed in equalising
the density, or in other words in forcing the return air down a
descending plane; while on an ascending plane the result is exactly the
reverse.*
The foregoing principles involve a yet undetermined point in mining— the
proper situation of the ventilating shafts. If the air of workings to
the deep of an upcast shaft be more easily conveyed to that shaft than
air to the rise of it, then we are not in doubt as to the abstract
principle which governs the right position of such a shaft. We might
even go a step further, and affirm, that if the question were one of
machinery employed in ventilating- mines, then that machinery (for
exhausting the air) ought to be placed at the extreme rise. But furnace
ventilation is of a more complicated character, because an element of
the ventilating* column is depth of shaft. I trust to be prepared, in a
short time, to bring this subject at large before the Institute, and
shall not, therefore, carry my present notes further, especially as they
have already extended much beyond my original intention.
* The case put is, of course, only for illustration.'
371 NORTH OF ENGLAND INSTITUTE
OF
MINING ENGINEERS.
ANNIVERSARY MEETING, THURSDAY, AUGUST 2, 1855.
Nicholas Wood, Esq., President op the Institute, in the Chair.
The Secretary having- read the minutes of the last meeting",
The President, after the proceedings of the Council had been read,
brief!y called attention to the recommendation of the Council as to the
propriety of the members of the Institute giving* their support to the
intended Museum at the Coal Exchange, London. The Council recommended
that mineral specimens, and other objects of interest, should be
forwarded to the Coal Trade office for transmission to London.
Several new members were then proposed for election at the next monthly
meeting-; and one g-entleman, viz., Mr. Benjamin Plummer, was duly
elected a member.
The President said, that he had just received a letter from Mr. Matthias
Dunn, in which that g-entleman presented to the Institute his two works
on the History of the Coal Trade, and a Treatise on the Mining- and
Working* of Coal. He (the President) beg*ged, in acknowledging* Mr.
Dunn's gift, to move a vote of thanks to that g-entleman.
The motion, on being- put, was carried unanimously.
The President next called attention to the propriety of the Institution
being- furnished with all the Reports published of the Inspectors of
Mines.
Mr. Dunn said, that there were three separate Reports published. If
Vol. III.—August, 1855. ccc
372
they passed a resolution, it might be forwarded to Sir George Grey, and
perhaps they had better ask for more than one copy of each Report.
Mr. Hugh Taylor, Chairman of the Coal Trade, thought the Reports of
considerable interest to the Coal Trade; and suggested that as many
copies as could, should be obtained, with the object of diffusing the
information they contained to all connected with the trade.
The President then submitted the following resolution on the subject:—"
That application be made to Sir George Grey, Secretary of State for the
Home Department, requesting him to favour the North of England Institute
of Mining Engineers with copies of the Reports of the several Inspectors
of Mines, from the period of their appointment under the act," which,
being put to the meeting, was carried unanimously.
The President then referred to Mr. Atkinson's paper, and suggested that,
as the original paper, together with the abstract, and correction of
some errors would be printed in this year's volume of Transactions; he
thought it would be desirable to print Mr. Taylor's observations
likewise, in order that the whole might be discussed together. The whole
subject being thus placed before them, they might then fix a day for the
discussion of it.
Mr. Atkinson thought that would be the best way, as members would have
an opportunity of considering any doubtful or disputed points.
Mr. T. J. Taylor said, that if the meeting consented, he would put his
remarks forthwith into the printer's hands.
After a few words from Mr. Boyd, approving of such a course, Mr.
Taylor's remarks on Mr. Atkinson's Paper, entitled " Observations on the
Theory of the Ventilation of Mines," was, after some discussion, ordered
to be printed with the volume of the Institute's proceedings for the
present year.
Mr. T. J. Taylor then read a paper, entitled an Account of the
Performance of a Ventilating Machine,* on Struve's Principle, at Middle
Duffryn Colliery, North Wales, by Mr. Samuel Dobson.
At the termination of the reading of this paper a brief discussion
ensued, which ended in several questions having been agreed to be
submitted for Mr. Dobson's consideration, for the purpose of throwing
some light upon a few unexplained points in the paper, and it was
arranged that the paper should be brought before the Institute at their
next meeting.
* See Volume IV.
373
The Secretary then read the Finance Committee's Report, and
Mr. T. J. Taylor read the General Report of the Institution for the past
year.
Mr. Taylor then drew the attention of the meeting to that part of the
Report having reference to the Fossil Flora Collection of Mr. Hutton,
comprising the specimens used in getting up the Fossil Flora Publication
of Messrs. Lindley and Hutton; and, in doing so, observed that the
collection in question was at present in Newcastle, and in the hands of
a private individual who was willing to dispose of them. The gentleman,
however, had been in treaty with some parties without success, but at
present there was an application from the Coal Exchange, London, and a
bargain was likely to be struck for them. He, for one, thought it
desirable to retain them in that part of the country, as they
unquestionably were the best collection of the kind ever made connected
with their own coal fields, and would serve to illustrate standard works
on the subject. At the last meeting of the Council the subject was fully
discussed, and every one present thought it desirable to secure the
collection, if it could be obtained at a moderate cost, and consistent
with the rules of the Institute. There were several hundreds of
specimens which, it was stated, would cost £140, the whole being within
ten or twelve cases, which would cost other £20, making altogether the
sum of £160. He knew that some doubt at first existed as to whether the
funds could be applied for such a purpose, but after examining the rules
the Council could not perceive that it would be improper to do so,
especially as rule 10 set forth generally that the funds were placed at
the discretion of the Council to dispose of. Under these circumstances
the Council resolved to leave the matter for the general meeting to
decide, as to whether the collection should be purchased or not 1 At one
period it was in contemplation to purchase them by the contributions of
individuals, with the ultimate view of presenting them to the Institute,
but after all it was considered a better course to make the purchase at
once, provided the terms could be arranged.
TheP resident thought it would be a great pity to let the specimens go
out of the district, especially as they were looking forward to the
establishing of a Mining College, in which case the collection would be
extremely valuable.
Mr. Hugh Taylor fully coincided with the propriety of obtaining the
collection in question; but before the Institute could purchase, the
first thing to be decided was, had they power to apply the funds to such
374
an object. If they thought they had, then they could not do better than
at once close a bargain for the collection, which was invaluable. It was
well known that Mr. Hutton was one of the first geologists of that
county; and, in his opinion, the collection might legitimately be termed
a " stone book! "
After a few observations from Mr. Elliot and Mr. Boyd in favour of the
motion, the following resolution was proposed and agreed to:—
" Resolved—That a purchase he made of the Fossils of the coal formation
used in illustrating the Fossil Flora of Messrs. Lindley and Hutton,
provided the Council approve of it on inspection of the Fossils, and can
procure the same at a sum not exceeding £140, exclusive of the cost of
the cases containing them."
Mr. Matthias Dunn said, he had then great pleasure to propose a
resolution, which, he felt confident, would be unanimously adopted; it
was, " That a vote of thanks be given to the President and
Vice-Presidents and other Officers of the Institute, for the able manner
in which they had conducted the affairs of the Institute during the past
year."
Mr. Hugh Taylok having seconded the motion, it was carried by
acclamation.
Some conversation next ensued relative to the propriety of changing the
hours of assembling at the respective monthly meetings, many members
expressing it as their opinion that it would be better to alter them.
Ultimately the following motion was made and agreed to on the subject:
" Resolved—That in future the meetings of the Council, preparatory to
the General Meeting, shall he held at 12 o'clock, and the General
Meetings at 1 o'clock on the respective days of meeting, instead of 1
and 2 o'clock respectively as heretofore."
A vote of thanks was also passed to Edward Boyd, Esq., and other members
of the Finance Committee, for the able manner in which they had
conducted the financial business of the Institute.
The meeting afterwards broke up, when the members present, together with
several other gentlemen, dined together at the Queen's Head Hotel in
honour of the third anniversary of the Institute.
NEWCASTLE UPON-TYNE: PRINTED BY ANDREW REID, 40, PILGRIM STREET.
AN ABSTRACT OF THE ALPHABETICAL LIST
OF PITS IN MR. T. Y. HALL'S PAPER * ON THE
GREAT NORTHERN COAL FIELD,
SHEWING THE
NUMBER OF COLLIERIES TO BE ABOUT 136,
NUMBER OF FIRMS TO BE ABOUT 90,
NUMBER OF PITS FOR SEA SALE TO BE ABOUT 200,
FOR SHIPMENT AT THE UNDER-MENTION'ED PORTS IX DURHAM AND
NORTHUMBERLAND, VIZ :—NEWCASTLE, SHIELDS, SUNDERLAND, SEAHAM,
MIDDLESBRO', COWPBN OR SEATON SLUICE, BLYTH, AND AMBLE NEAR WARKWORTH.
1854.
H household; S steam ; G gas; C coke; CG coke and gas; CH coke and
household ; HG household nn<l gas¦; HGC household, gas, and coke.
LADY F. A. VANE LONDONDERRY.
NAMES OF PITS. NAMES COALS SELL
BY.
1 Antrim Adelaide, Lady A. V.L. | Stewart's W.E........_____II
2 Alexandria, Lady Vane L. Eden Main................H
10 Broomside, Lady Vane L. Pensher W.E............... H
112 Lady Seaham Pit, Lady V. L. Stewart's Steam ............ S
122 Meadows, Lady Vane L. Seaham W.E............... H
128 Old Durham, Lady Vane L. Old Ducks ................ II
134 Pensher, Lady Vane L.
135 Pittington, Lady Vane L. Nut Coals, Bean Coals, Small
Coals
140 Rainton Pits, Lady Vane
141 Resolution Pit, Lady Vane 143 Seaham, Lady Vane L.
EARL OF DURHAM.
11 Brass-side, Earl of Durham Lambton W.E............... II
99 Houghton-le-Spring, Earl of Lambton's Primrose.......... H
Durham Frankland W.E............. H
109 Little Town, Earl of Durham
111 Lady Durham Pit, Earl of D. Steam Boat Hartley.......... S
126 Newbottle, Earl of Durham Little Town W.E............ H
145 Sherburn, Earl of Durham Newbottle.................. H
146 Sherburn House, Earl of D. Ditto ..................
S
149 Shadforth, Earl of Durham Nut Coals, Bean Coals, Small Coals
*See Volume II.
Vol. III.
a
[iij
HETTON COAL COMPANY. Hon. A. Cochrane and Partners.
NAMES OP PITS. NAMES
COALS SELL BY.
61 Eppleton Hetton Pits Hetton W.E............... H
02 Elemore Hetton Pits Hetton Lyons.............. S
100 Hetton Lyon's Pits Hetton West Hartley ........
H
! Nut Coals, Bean Do., Small Do.
NORTH HETTON COMPANY.
Earl of Durham and several of Hetton Owners, Viz :— Messrs. Wood,
PhilipsOxN, Burrell, & Others.
00 Dunwell, North Hetton Russell's W.E.............. H
80 Grange Low, Do. Ditto Lyon's ..............
H
97 Hetton North, Hazard Pit Nuts, Beans, Small
120 Moorsley, North Hetton
142 Seaton, 'Hetton Seaton,
W.E............... H
82 Grange Kepier Kepier Grange, W.E.........
H
SOUTH HETTON COMPANY. Forster, Walker, Burrell, Green & Co.
96 Hetton South Pits South Hetton W.E..........H
119 Murton Pits, South Hetton Braddyh's W.E............. H
144 South Hetton Kelloe Pits,
M. Eorster, P. Forster, Richmond Mayne .......... H
Burrell, and Green Trimdon Grange, W.E.......H
162 Trimdon Grange, J. Forster, Nuts, Beans, Small M.P., South
Helton
HASWELL COAL COMPANY. Messrs. Clark, Taylors, Plummer, Lambs, Maude,
Laws, & Bell.
101 Haswell Pits, Do. Co. Richmond Main ............ H
147 Shotton Grange, Haswell Haswell W.E............... H
Company Plummer's W.E............II
Ryhope New Pits, commenced Shotton W.E...............H
sinking Easington W.E............. H
Shotton U.S............... H
Nuts, Beans, Small
MESSRS. BELL AND PARTNERS. 12 Belmont, Bell, Backhouse, & Belmont
W.E............... H
Co. Nut coals, Bean do., Small
do. 50 Lambton's D. Pits, resumed, Lumley W.E............... H
II. Stobart, Bell, Crawford,
& Co.
90 Harraton, Stobart, Bell & Co. I Harraton.................. S
110 Lumley, Stobart, Bell & Co. | West Belmont.............. II
91 Hough-hall, Bell, Backhouse, I
and Davison ; Lumley W.E............... H
148 Shincliffe, Bell, Backhouse, I Belmont W.E............... IT
and Davison '
[in] MESSRS. BELL AND PARTNERS, Continued.
NAMES OF PITS. NAMES
COALS SELL BY.
150 South Moor, Bell and Co. Bell's Primrose ............
G
155 Shield Row, Bell and Co. Harrison's W.E............. II
Eton do................... H
181 Washington, Bell and others Washington W.E........... G
Do. U.S................... G
121 Monkwearmouth Pits, Bell & Bell's W.E................. H
others Wearmouth W.E........... H
i/vyj-i-u JDUVYIiiD AINU UU.
Messrs. Bowes, Hutt, Wood, and Chs. M. Palmer.
113 Marley Hill Pits, J. B & Co. Marlev Hill................ C
46 Crookbank, J. Bowes and Co. Clavering's Tanfield ........ C
25 Burnopfield, Do. Wood's Garesfield
.......... C
58 Dipton, Do. —Sinking to
another Seam
133 Pontop, J. Bowes and Co. Original Windsor's Pontop .
CG
77 Greencroft, J. Bowes & Co. —Not working: laid in
7 Andrew's House, J. Bowes & New Tanfield.............. CG
Co.
127 Norwood Old Pit, J. Bowes Norwood.................. C
and Co.
Shipcote, J. B. and Co. Shipcote............... CH
103 Kibblesworth, J. Bowes and Ravensworth Pelaw........ OH
Co.
116 Mount Moor, J. B. and Co. Mount Moor .............. H
156 Springwell, J. B. and Co. Peareth . ................
H
104 Killingworth, Do. Wharncliffe
Wallsend........ H
151 Seaton Burn, J. B. and Co. Killing* worth Do...........H
b7 Delight Pit, Do. Ravensworth West Hartley
.. H 136 Peareth Old Pit, J. B. & Co.
NICHOLAS WOOD.
13 Black Boy, or Tees W.E., N. Tees W.E................. H
Wood Tees Hartley—Splint........ H
Coundon, T. W. E., N. W. Coundon W.E............. H
108 Leasingthorne, T. W. E., N. Leasingthorne W.E.........H
Wood
195 Westerton, T. W. E., Nich. Bishop's Tees.............. H
Wood
W. BLACKETT, N. WOOD, ANDERSON, AND PHILIPSON. 87 Harton, St. Hilda and
Jarrow [ Harton, St. Hilda, Jairow .... 1
THORNLEY COAL COMPANY. Thomas Wood, Gully, Chaytors, Burrell.
107 Ludworth, Thornley Co. ' Ludworth W.E............. H
174 Thornley Coal Company's Thornlev ................HG
Pits Ditto .".................
CG
163 Trimdon, Thos. Wood, Gully, Harvey.................. CG
and Burrell Trimdon W.E............... II
[iv] JOS. PEASE. JOSEPH WHITWEL PEASE, & JOS. PEASE & CO.
NAMES OF PITS. NAMES COALS SELL
BY.
4 Adelaide Shildon, J. Pease Adelaide W.E............. H
59 Deanery, J. Pease Deanery W.E...............
H
24 Bowden Close, J. W. Pease Bowden Close U.S........... C
69 Eldon, J. and H. Pease Eldon W.E................. H
94 Hedley Hope, J. Pease Hedley Hope U.S........... C
102 Jobshill, J. Pease I
Jobshi'li.................... C
138 Roddymoor West Pits, J. P. Pease's West W.E........... C
139 Roddymoor East, Do. Roddymoor East............ C
159 St. Helens, J. Pease St. Helens W.E............
H
191 Woodhouse Close, Sir diaries Clavering's W.E.,........... H
Maclean coals, wrought by Woodhouse Close .......... H
Mr. Heckless for J. Pease
EDWARD RICHARDSON & CO.
5 Acorn Close or Cbarlaw, E. R. Acorn Close W.E...........H
43 Cresswell, Anfield PL, E. R. Cresswell.................. H
54 Castle Pit, E. R.
56 Derwent, E. R. Elm Park.................. H
70 Eden, E. R. Eden W.E.................
H
117 Medomsley, E. Richardson Medomsley................ H
154 Spital Tongues, E. R. Spital Tongues ............
H
123 Medomsley Old, J. Richardson Old Medomsley ............ C
Langley
JAMES JOICEY.
31 Beamish, Joicey Beamish South Moor Main
.. H
161 Stanley East, Joicey Beamish Unscreened........
H
169 Twizell, Joicey New Pelton Main
.......... C
165 Tanfield East, Joicey Old Tanfield
.............. C
171 Tanfield Lea, Joicey Bute's Unscreened Moor, Lady
Windsor's Tanfield, Windsor's
Pontop, Simpson's Pontop .. H
170 Tanfield Moor, J. Tanfield Moor, South
Pontop.. C 173 Tanfield South, J. South
Tanfield W.E......... C
Ditto Unsereened .......... C
STELLA COAL COMPANY.
Executors of the late J. Buddle—T. Y. Hall, Chas. & Addison Potter, & M.
W. Dunn.
172 Townley West, Stella Coal West Townley W.E.....H & CG
Co., Whitefield Ditto U.S., Whitefield ......
C
175 Townley Stella Coal Company Stella W.E.............H & CG
Freehold Pit Townley Glebe...........CG
176 Townley Glebe Pit, Do. j off Stella Coal Co., W.E. . .H & CG
177 Do. East, Emma Pit, Do. Small Coals
w
ROBSON AND JACKSON.
NAMES OE PITS. NAMES COALS SELL
BY.
17 Binchester and Newfield Newfield.................. C
21 Byer's Green Byer's Green
W.E........... C
35 Bowburn Ditto
U.S................. C
39 Clarence Hetton Bowburn..................
C
40 Crowtrees Clarence Hetton
W.E....... H
48 Coxhoe, or Kelloe Crowtrees W.E.............
H
92 Heugh Hall So. Kelloe, Coxhoe Do. WE.
H
95 Hetton West Heugh Hall W.E...........
H
98 Hunwick Pit West Hetton W.E...........
H
Hartley W.E.............HG
Ditto U.S................, C
53 Little Chilton, J. R., Mangr. Little Chilton W.E........... H
R. P. PHILIPSON.
37 Cassop, Philipson Cassop W.E...............
H
38 Cassop Moor, Philipson St. Cuthbert's W.E...........
H
MESSRS. CARR AND PARTNERS.
32 Burraton, Carr and Co. Burraton................ HG
41 Cowpen, Carr and Co. Cowpen.................... S
83 Hartley, Carr and Co. Felling U.S................. G
153 Seghill Pits, Carr and Co. Carr's Hartley.............. S
72 Felling Pit, Carr, Potts, & Co. Seghill....................- S
Earsdon, Messrs. Taylor Earsdon W.E............... H
88 Holywell Old Wt., Plummer, Holywell West ............ H
Taylors, Clark, and Lamb
89 Holywell New East, Do. Holywell East.............. H
42 Cramlington East Pits, J. t West Hartley.............. S
Lamb, Potters, and Co. Seaton Delaval ............ S
152 Seaton Delaval, Lamb, Scott, Hasting's Hartley .......... S
Barnes, Burdon, and Co. Walbottle.................. II
183 Walbottle, J. Lamb, Potters, Holywell ............... HGC
Jobbing's Trustees
167 Tyne Main, Losh and Co. Tyne Main ................ G
73 Friar's Goose, Do. Do......................
G
74 Jjramwellgate Moor, J. Bell Framwellgate............. CH
and Hunter
130 Ouston, Hunt and Co. Ouston .................. CG
179 Urpeth, Hunt and Co. Urpeth W.E............... CG
Do. U.S. ............... CG
132 Pelton Moor, Swaby and Co. Pelton.................... CG
Do. U.S.................. CG
[vi] CONSETT IRON COMPANY.
NAMES OF PITS. NAMES COALS SELL
BY.
44 Crook Hall, Consett I. Works Used for Iron Works.
51 Conside Do.
Do.
52 Conside Pits, Iron Co. j Do. Do.
GEO. ELLIOTT, JONASSHON.
129 Oxclose, Elliott & Jonasshon Oxclose W.E............. HG
178 Usworth, Elliott & Jonasshon Usworth W.E........... HCG
125 Nettlesworth, E. and J. Nettlesworth W.E......... HG
MESSRS. COOK AND C07~
45 Uastle Eden Pit Castle
Eden............*... H
Do., Steam ................ S
~MESS~RS. HEDLEY'ST" ~~
47 Crag-head, Hedley Crag-head................ HG
93 Homeside, Hedley Homeside ..................
H
EXECUTORS OF MESSRS. imANDLING.
81 Gosforth Gosforth
W.E............... H
55 Coxlodge, Bell and Brandling- Brandling- Main......,...... H
Riddell's W.E.............. H
Coxlodg-e................ HG
' MR. TYZICK.
66 Edmondsley, Tyzick | Edmondsley W.E.........HG
DALT(JW AND C(J ¦
84 Heaton, Dalton and Co. | Heaton W.B.............IIG
-MEgSRS> EAST0JN AND co\
131 Oakwellgate, Easton and Co. I Oakwellg-ate U.S...........G
85 Hebburn, Do. j Hebburn
.................. G
J. B. PEAliSDNXNlTcor-
86 Hewortb, J. B. Pearson & Co. Heworth U.S.............HG
Dean's Primrose............ H
106* Kepier, Dixon Ralph Kepier W.E............... II
COOKSON, CUTHBERTS, AND LIDDELL~!
114 Mickley, by dayhole drift from West Wylam W.E......... HC
_______surface, C, C.. and L._______Mickley U.S............. HC
118 Marshall Green, Skinner_______Skinner.................... C
24 Netherton Pits, Birkinshaw's Netherton .................''. S
Trustees
W. W. BURDON, W. BARKUS,TUN., AND CO. "
8 EightonMoor Eighton Moor W.E......V HG
16 Broomhill, W. Barkus, Mur- Broomhill.................. S
ray, and Burdon Allerdean.................. II
Allerdean, W. W. Burdon
36 Black Prince Pit, Attwood Coal mostly consumed by their own
166 Thornley, Towlaw, A. and Co. Iron Works at Towlaw and
168 Towlaw L. S. Pits, Attwood other places
71 Elm Park
[vii]
NAMES OP PITS. I NAMES COALS SELL
BY.
184 Wylam East, J. B. Blackett, I Wylam.................. HG
31.P. | Prudhoe Main..............
G
185 Waldridge, Sowerbv & Co. Waldridge W.E............. G
Ditto U.S.................. G
187 Whitworth, R. & J. Whitworth W.E............. G
Ditto U.S.................. G
190 Witton Park and Witton, Witton Park................ C
Kirsip
192 Whitwell, J. M. Og-den | Whitwell W.E............ HG
193 Wingate Grange. Lord Howdon W.E............... H
Howden Caradoc W.E............... H
197 Walker, Lambert and Co. Walker W.E............... H
Pott's Primrose ............ H
SOLD TO JOSEPH & JOHN HARRISON IN 1854. 137 Radcliffe Pit
| Radcliffe .................. S
160 Stanley East, Burn & Co. | East Stanley.............. CG
180 Wingate South, F. South Wing-ate............ HS
Ditto...................... S
STRAKER AND LOVE.
19 Bitchburn South Bitchburn..................
C
23 Brancepeth Brancepeth
................ C
158 Willington or Sunny Brow Willington ................ C
BOLCKOW AND VAUGHAN.
6 Auckland West, Bolckow & West Auckland............. C
Vaughan Etherley New.............. C
67 Etherley New, B. & V. Wood Field................ C
188 Woodifield White Lee
................ C
194 Whitelee These mostly used for
their own
Iron works
HENRY STOBART AND CO.
20 Bitchburn North, H. Stobart North Bitchburn............ C
and Co. Old Etherley
.............. C
68 Etherley, Old, H. Stobart
MARQUIS OF BUTE'S EXECUTORS. 76 Garesfield Co , Chopwell |
Garesfield U.S............GC
[viii]
NAMES OF PITS. | NAMES COALS
SELL BY.
9 Ashington, Harrison, Garr, Portland Hartley............ S
and Co.
14 Backworth, Waldie and Co. Northumberland W.E........ H
182 West Cramlington Pits, Backwortli ............... H
______Waldie and Co.____________Buddie's West Hartley........ S
DAVISON, EASTON, ANDERSON, STODART, BATES, AND HENDERSON.
15 Bedlington Pits, D & Co. j Davison West Hartley........ S
31 Barrington Pits, Longridge Longridge's West Hartley .... S
Begbie's Hartley............ S
26 Burnopflat, Sowerby & Robt. Burnopflat W.E............ HG
Fletcher Ditto U.S................. HG
28 Blaydon Burn, Joseph Cowen Blaydon Burn ............ CG
Ditto U.S................. CG
30 Blaydon Main, G. H. Blaydon Main ............ CG
Ramsay Ditto, U.S................. G
78 Evenwood, Armstrong Evenwood................ HG
Gordon.......<.......... HG
157 Sacriston, W. H. Bell | Sacriston W. E.............H
22 Bitchburn New, Muschamp | New Bitchburn ............. C
27 Bebside N. Pit, Lambert & Co. | Bebside.................... S
18 Butterknowle & Copley Bent, Butterknowle .............. C
Prattman's Trustees Copley Bent...,............ G
115 Morpeth Banks Old Pit |
33 Burdon Main, Hope, landsale | B urdon Main............... C
79 Gordon West Old Pit |
75 Fenham Old Pit | Fenham.................... G
63 Elswick oldTit | Elswick.................... G
64 Elswick Low Do. | Elswick Low ............... G
Wallsend pit, resumed at Wallsend.................. C
this time by Losh, Wilson,
Bell, & Co.—Nov. 1854____________________________
The iron ore districts alluded to are three in number, viz.:—one in
VVeardale, Durham, one in Ridsdale and Hareshaw, in Northumberland, and
the third in Cleveland, on the coast, extends from west of Redcar
southward beyond Roseberry Topping to Whitby, covered in many places by
a large common of fine peat turf. This peat may hereafter become
valuable for reducing the bulk and weight of the refuse stone from the
iron ore, by roasting, to double its per centage, so that it may be
shipped and conveyed at one-half the cost to the Tyne and other places
where suitable coal and furnaces are found for smelting and
manufacturing it.
[ix] RECAPITULATION
OF
COLLIERIES, FIRMS, PITS, AND WORKMEN;
ALSO THEIR PRODUCTIONS.
From the foregoing alphabetical list, also the list of pits, comprising
about 136, of the several large as also small collieries, it will be
seen that there are 192, or about 200 working pits, exclusive of
landsale pits, which are considered of little account in this coal
district. It is, however, well known that 10 or 12 out of the 192
mentioned have been off work during the past year; they are, however,
partly made up again by divided shafts, making- double pits, such, for
instance, as at Haswell, Hetton, South Hetton, Thornley, and others;
besides, we. must add, instances of three or four new pits sinking-, and
which are about to commence working. The number may, therefore, at
present be fairly estimated at 200*; but, as to the number of firms or
lessees of collieries, these may be said to be less—say 80, deducting 10
off work, and these I could easily print in another list, without the
names of the pits, but with the names of the collieries and the lessors,
opposite each of the lessees, if the Council of this Institute deem such
expedient. The above may be considered to be generally correct, yet,
after all, it is possible for some error to have crept in—it cannot,
however, amount to anything sufficient to affect the calculation herein
submitted. The following table (made up from that on page 206f) shows
the number of underground men and boys employed in one pair of pits, or
a shaft divided, so as to make two pits, viz.:—Haswell, which in itself
vended 200,000 tons in one year, and one of the single pits, the Emma,
belonging to the Stella Coal Company, which vended 100,000 tons in one
year. The statement, as under, will form a correct guide for the greater
proportion of the remaining pits, and staff of underground hands:—
Abstract of Staff Safety Staff. nfF , , „ ,,
brought from page Hewers.------------------- Utt-nana gutters Totah
103. Men. Boys. Men. K ^oys
Haswell Pits...... 210 60 13 19 126
428
Emma, near Ryton.. 98 19 8 9
45 179
____________________308 79 21 28 171
607
* Including ten or a dozen pits where feeders of salt water have been
found, alse, the like number where pent up gases have been found in
cavities, and when those cavities are cut into, have, on account of the
great pressure they had been confined at, come oft' in great force, then
g*enerally termed a blower.
t The figures in this and two following Pages refer to Vol. II.
Vol. III.
h
These totals show that the work of each hewer, or cutter of coal,
averages 1,000 tons annually, or 8| tons per day, reckoning- 273 days
for the year ; hut if the safety-staff, off-hand men, and hoys he
included; the average will then he only 494 ton3 annually. This
estimate, however, excludes the men and hoys engaged at the bank, or the
top of the pits. It may here he further observed, that although the
greater portion of coal in the northern coal field is more tender in
quality than in the district in which the two pits alluded to are
situated, the calculation given may still be relied upon.
If these bases be admitted, then we can easily estimate the grand total,
as follows :—
By referring to Chapters XIX and XX, pages 203 and 204, it will be seen
that, the total vend in the year 1853 was 13,333,000 tons, and if we
assume, for argument's sake, that the same vend will take place in 1854,
and calculating the pits as heretofore stated, then the entire number of
men and boys employed underground will be 26,977, giving an average of
140 hands for each pit, with an average quantity of coal produced at
them of about 70,000 tons. But it must be recollected that, although the
average is 70,000 tons, yet some of the collieries possess two, three,
four, and even six pits, consequently, when we give the collieries as a
whole at 136, the average of each colliery will be 100,000 tons instead
of 93,681 tons, and 58,000 tons for one pit, as previously stated in
page 102.* If, in addition, the working firms are estimated at 80, as
some are not in operation at present, then the average of each firm will
be about 166,625 tons. But, assuming the working pits to be dispersed
uniformly over the 750 square miles of the northern coal field, that
would only average about 3| square miles for each pit; and, further, if
those pits that are called landsale pits—as well as those others
mentioned as being off work, but being resumed—would make the total 300,
or more than the average, they would only give 2g square miles for each
pit. The old pits will all be available to a certain extent hereafter;
and, as the 136 collieries, or 200 pits, are fit out with engines and
all other necessary appendages, they show a very encouraging view of the
coal district, only averaging 53 square miles for each colliery. It
cannot, therefore, in future be necessary to expend much capital in
sinking more pits over this limited and circumscribed coal field. It
will further be seen, by referring to pages 284 and 285, that twelve or
sixteen of the largest of the present colliery owners hold in themselves
one-third (or 200 square miles), leaving 550 square miles, which is
partly worked out already, and part may never be worked; this will
reduce the 750 square miles, and give an average for the remainder of
the present collieries, viz. 120, of 3f square miles for each colliery
or firm.
* When this low average was taken into account the 27 landsale pits were
included. By reference to Chapter XX, pages 204 and 205, it will be seen
that the Lancashire, Cheshire, and North "Wales coal district requires
939 pits and day levels, with 31,950 underground workmen, to produce
9,923,000 tons yearly, making an average of each pit per day of 39 tons,
or 10,558 tons yearly with 34 men—on an average each producing 31] tons,
which leaves 1 l-7th to each collier per day. Scotland employs 22,250
men and boys for 7,250,000 tons—equal to 340 tons for each underground
hand yearly. Lancashire and Scotland coal principally used for home
consumption.
[Xi]
The total number of workmen at this time, 1854, may be divided thus:—
\ or 3-6ths. .13,500 hewers, averaging 1000 tons annually. -. pi f
3,300 safety-staff men.
£ 1,400 boys belonging to the safety-staff, i o nti ( 1,200
off-hand men, bargain work, &c. 3 " \ 7,600 putters and
boys.
27,000 makes an average of 494 tons.
This also gives a very encouraging view of the state of the trade, and
the advantages arising to the workmen from being better employed. For
instance, if we refer to Chapter XVII, page 197, it will be seen that in
the year 1844^—and this statement is taken from a printed document—the
total number of men and boys employed was 25,383, and the vend then
produced 9,623,922 tons. If, therefore, the vend with the number of
hands employed be compared with the vend and number of hands in 1853, it
will clearly prove that the workmen could not have been fully employed
in 1844, for, instead of producing no more than 9,623,922 tons, they
ought to have produced 12,600,000, or more: besides, the average produce
of the men and boys in 1844 was only 382^ tons, while in 1853 it was 494
tons. Thus I find that the increase of underground workmen from 1844 to
1853 is not more than 2,000 altogether, which for nine years is only an
increase of about 200. By taking- into account the amount of work the
200 a-year extra hands could perform in the nine years, it shows that
the same number of old hands in 1844 have evidently gone on gradually
increasing per workman from 382| to 494 tons yearly, over a period of
nine years; but if we take the work of the hewers alone, it will be seen
that they averaged, in 1844, 764| tons, while at the present time they
average 1000 tons each*, rather more than 3f tons daily.
That gradual average increase will be seen as follows:—
In 1845 1846 ^4g7 1849 1850 1851 1852 1853 1854
__________________________
TJ 790 618 8421 868 894 920 946 970 996
Hewers........
Total underground 394 4Q4 J ^2 454 466 4?g 4Q4
hands, &c.....
Notwithstanding, these statements being true, yet still it cannot be
said that the men have arrived at a fair maximum of work, as they are
quite capable of doing more, although both extra work and higher prices
are given to them than in 1844. But it is also a surprising fact,
that
* It must be recollected that, in the year 1844, the men commenced an
obstinate strike, which continued for 19£ weeks; but ultimately they had
to give in after enduring a great loss to themselves and families:
while, on the other hand, the coal-owners suffered great loss through
the strike, and at length had to introduce, at g'reat expense, new hands
from coal mines in Wales, and sundry lead mines and various other
places.
[xii]
the hewers generally prefer working- for 4s. 6d. or 5s. per six hours,
when thej actually could earn 7s, in eight hours, when the demand for
coals for shipment is great. If this disposition of the men be
persevered in the consequence will be, that if the demand should
hereafter increase, the workmen will either have to exert themselves, by
breaking through the ill-advised rule they have adopted among
themselves, or else they will find, in the end, that they will drive
parties to get supplies at other distant districts; or, on the other
hand, the coal-owners of Durham and Northumberland will be driven to
resort to more mechanical means, or introduce a sufficient number of
hands from a distance to work the extra quantity of coal required. If
that be so, the probability will be, that some reduction in the quantity
of work performed by each underground hand, that is, at piece work, will
ensue, to the detriment of the present local workmen, as the extra hands
or coal-cutting machines that may be brought into the doal pits in this
field will tend to reduce the wages of the present local staff.
COAL-CUTTING MACHINE.
About a month ago the writer -was down one of the pits belonging" to the
Earl of Balcarres and Crawford, in company with Mr. Peace, the manager,
who is the inventor of a machine for cutting coal, worked by means of
compressed air, with two 3^-inch cylinders, up to six-horse power—it was
then finishing a piece of work it had been set to perform.
On applying the flexible air-tube, about an inch in diameter, between
the small metal air pipe and the machine, it commenced cutting the coal,
and completed a piece of work 200 yards long, 5 yards wide, and 4J feet
high, with wonderful alacrity, and without any visible means of
producing so great a power.
The machine is very compact, being only about 3 feet long by 2 feet wide
and 2 feet high. It is so constructed that it will either travel on the
rails of the tub carriageway, or on the sill of the mine, by means of
castors which are made to work in any direction by a man pushing it. The
cutters move forward by their own power, four feet in length, while the
machine remains fixed.
The inventor is now making one of 10-horse power, which will be better
adapted for general use, it being so finished as to cut the blocks
better fitted for market: the former one cuts perpendicularly and
underneath the coal four feet—dust waste very little—the width of the
cut being* two inches. Machine No. 2, like No. 1, is a complete and very
strong piece of workmanship, being wholly of iron, metal, and brass, is
also so adapted as to cut horizontally and vertically. This is a great
advantage ; and being worked by compressed air, the refuse considerably
improves the ventilation of the mine.