Courriéres Explosion

The total power of the engines employed at the mines was about 130,000 h.p., of which nearly 12,600 h.p. was used electrically. The mines of the Pas de Calais have been generally free from fire-damp. Owing, however, to the nature of the strata in which the seams lie, and the numerous faults due to the violence by which the strata have been disturbed, the roofs are bad and very careful timbering is necessary. In this respect the Courrieres Company is famous, having by their system of timbering and the use of iron bars in advance of the last settings, reduced their death rate from falls from 0 - 76 per 1,000 persons employed during the 10 years 1870-79 to 0-15 per 1,000 persons employed underground during the 10 years 1890-99.Hence at the Exhibition of mining industries held last year at Arras the first prize was awarded to the Courrieres Company for the excellence of their working and general arrangements.

In the Pas de Calais coalfield there was used of explosives in 1904, as follows :

Lbs.
Dynamite and gelatine dynamite - 274,201
Grisounite couche (for coal) - - 141,724
Grisounite roche (for stone) - - 31,238
Grisounites - - - - - 579,210
Favier explosives - - - - 297,557

Total - - - 1,323,930

No gunpowder was used in the mines.
The consumption of explosives amounted to 0' 08 lb. per ton of coal extracted.
None of the above explosives are submitted to a practical test for safety as in England. Explosives for use in mines producing fire-clamp, or in dusty mines, must satisfy the conditions stated in a ministerial circular dated 1st August 1890 :
1. The products of their detonation must not contain any combustible element, such as hydrogen, carbon monoxide, solid carbon, &c.
2. Their temperature of detonation must be below 1900° C. for work in stone, and 1500° C. for work in coal.
3. Each cartridge must bear a label indicating its composition, to enable the users themselves to verify the temperature of detonation according to a given formula.

Shot firing in mines worked with safety lamps is clone almost exclusively by electricity.
The Courrieres Company was formed in 1852 with a capital of 6,000,000 francs (240,0001.). The concession comprised 4,597 hectaires (10,350 acres), which was subsequently increased to about 5,459 hectaires (13,484 acres) covering an area 6z miles from north to south and 34 miles from east to west. The output has steadily increased from the commencement and the undertaking has proved very remunerative. Each year after . putting aside large sums for a reserve, and after the expenditure of much money on the mine, a considerable dividend has been paid. It is estimated that in this way at least some 60 or 70 millions of francs (ten times the original capital) has been expended on the mine, which last year yielded a dividend of about 6,000,000 francs or about 100 per cent. on the subscribed capital. The shares were, therefore, at a premium of nearly 2,000 per cent. The disaster has lowered. there, perhaps to two-thirds of their former value, but this depression will probably only be temporary.
In 1904 the Company raised about 7,500 tons per day from nine coal drawing shafts, making a total output of 2,267,043 tons for the year. The number of workpeople employed was 9,258 of whom 7,594 worked under ground. The total money paid in wages, and on the various institutions of the Company promoted for the benefit of the workmen, amounted last year to about 14 z million francs.
The following statement shows the number of men and boys ordinarily employed in all the pits of the concession :-

Pits. Morning shift. Night shift.
No. 1 1 -
2 563 212
3 539 161
4-11 768 292
5-12 702 210
6-14 813 292
7 679 305
8 282 80
9 642 287
10 529 260
---- ----
5518 2099

13 (sinking) 24 48

The Company has erected about 2,200 houses for the workinen at a cost of about 300,0001. which are let at very cheap rates, and accommodate about half the working population. The Company provides the workmen with coals free, and also contributes to the expenses of education.
An insurance fund exists to provide for illness and military service. To this the men contribute 2 per cent. of their wages, the Company adding an equal sum. To this fund is also added all fines incurred. In cases of illness an adult receives about 1 - 75 francs per diem, and younger workers proportionate sums. There is also a pension fund to which the men contribute 2 per cent. of their wages and the Company an equal amount. The pension commences at 55 years of age and amounts to about a penny per day for each year of service. In cases of accident the Company is liable to a workman and his dependants upon a scale- determined by statute. Widows also receive certain benefits. In case, however, it should be proved that the accident was due to deliberate negligence of the employer, the sum payable is about equivalent to full pay for the rest of the workman's life in case of total incapacity, and proportionate sums in other cases.
There are also co-operative supply Societies, clubs for shooting, music and singing, to which the Company subscribes.
It is estimated that these various payments by the Company, some of which are compulsory by law, others voluntary, amount to an increase of 11'89 per cent. on the wages.
Before proceeding to deal with the disaster it will be well to give a short description of the pits and seams affected by the explosion, which although not in great detail, may suffice for the purposes of this report.

4. The Departmental. Cominission presided over by M. Carnot.
5. Inquiries by the Courts of Justice into the inana,geznent of the mine prior to the explosion, and the conduct of the rescue operations. The report of the Courts of Justice should determine two points. First, whether the work that was done by the Courrieres Company would justify the revocation of the concession by which they hold the mine from the State. This will depend on Articles 49 and 50 of the law of 1810, as amended by the laws of May 1866 and July 1880 :
Article 49.
" Si l'exploitation est restretnte on suspendue. de maniere a inquieter la surete publique ou les besoins des consoznmateurs, les Prefets, apres avoir entendu les proprietaires, en rendront compte an Ministre de 1'Interieur, pour y etre pourvu ainsi qn il apparttendra.
Article 50 (texte nouveau, lot du 27 Juillet 1880).
" Si l.es travaux de recherche on d'exploitation d'une mine sont de nature a compromettre la securite publique, la conservation de la mine, la surete des ouvriers mineurs, la conservation des voies de connnunication, celles des eaux minerales, la solidite des habitations, Fusage des sources qui altinentent les villes, villages, hameaux et etablissements publics, tl y sera pourvu par le Prefet."
The second question which the Courts may have to decide is whether the Company has by its neglect rendered itself liable not only to pay the dependents of the victims of the explosion ordinary compensation, but to pay them the increased compensation provided by the law of 9th April 1898. (Article 20).
" Lorsqu'tl est prouve que Faccident est du a la faute inexcusable du patron on de ceux qu'tl s'est substitue dans la direction, Findemnite pourra etre majoree, mais sans que la rente on le total des rentes allouees pulse depasser soit la reduction soit le montant du salaire annuel."
On the 6th May the parliamentary elections took place, and the strike terminated by an advance of 10 per cent. on wages.
Since then the work of re-opening the mine and recovering the bodies has continued, and about 1,068 have now been brought to the surface.
It may be of some interest to reproduce here a calculation of the compensation that the Courrieres Company will have to- pay to the families of those who were killed. Several of these calculations have appeared in the mining journals, differing according to different estimates of the number of dependents. We give one of these which probably is an approximately
correct statement. The widows get the pay for life, the children until the age of 16 years. There are 7 7 widows without children who will get 20 per cent. of the workman's wages. This on an average wage of 1450 fr. per annum earned by the men killed amounts to - - 22,330 francs.
144 widows with one child at 35 per cent. - - 73,080 „
77 widows with two children at 45 per cent. - - 50,242 „
112 widows with three children at 55 per cent. - 89,320 „
144 widows with four children at 69 per cent. - 125,280 '
30 orphans at 20 per cent. of fathers' wages - 8,700 „
472 dependent relatives at 10 per cent:. - - 68,440 „
Total s 437,392 francs.

That is to say an annual sum of -17,5001. Subscriptions in France and elsewhere have provided a further sum of 7,023,520 francs to be divided among the families of the sufferers.
If the working is restricted or suspended so as to endanger the public safety or the requirements of consumers, the Prefects after having heard the proprietors shall report to the Minister of the Interior in order that the proper remedy may be applied.
If the explorations or workings of a mine are of a nature to compromise the public security, the maintenance of the mine, the safety of the working ininers, the preservation of ways of communication, those of mineral waters, the solidity of houses, the use of springs which supply towns, villages, hamlets and public establishments, the Prefect shall have jurisdiction.
+ When it is proved that the accident is due to the inexcusable fault of the employer or his agents the compensation may be increased, but so that the amount awarded shall not exceed the annual average wages.

We have omitted to describe the accusations that have been made against the Company and the State engineers.
Excuse must be made for violent language after so deplorable a catastrophe. We hope that many of the journals and persons who have made bitter attacks against men who were daily risking their lives to save the survivors, will in calmer moments do justice to the engineers of the State and Company and recognise the falsity of the odious charges that have been made against them. The general conclusion at which we have arrived, is that the explosion was an extensive and very formidable dust explosion, without in all probability the presence of any gas.

The reasons for this view are as follows:

The mine was singularly free from fire-damp, so much so that it was in great'part worked with naked lights. In order to assume.that the explosion was chiefly caused by fire-damp, it would be necessary to show that an explosive atmosphere existed and had suddenly appeared over large areas of the mine in air currents coming from different sources. But how are we to believe it possible that such conditions existed, and from what sources are we to suppose the inflammable gas proceeded?
Added to this the explosion was particularly violent in many of the intake air-ways, places where it is most improbable that fire-damp would be present. The idea of a fire-damp explosion like this is to us inconceivable, and so far as we are aware there is nothing to support such a theory.
There does not appear to be any evidence, either from survivors of the explosion, or from the positions in which the bodies of the victims were found, that any of the workmen had been alarmed, before the explosion, by any unusual occurrence, such as the unexpected appearance of inflammable gas, or that any one had seen the gas on a lamp or light.

Neither was anything observed in the mine to support the idea that accumulations of fire-damp in old workings or goaves had contributed to the explosion, and no fire-damp has been found anywhere since the explosion.
Some of the roads traversed by the explosion, as will be explained hereafter, were in a different condition when we saw them to what they bad been before the explosion; but so far as a judgment could be formed, all parts of the mine traversed by the explosion had contained much inflammable dust,. On the other hand many instances were observed -where the explosion ceased on arriving at places where dust was either absent or of a very shaley nature.

Deposits of charred or partially coked dust have been observed in all parts of the mine traversed by the explosion, including intake airways, affording good evidence of the passage of flame, and that the flame had been almost co-extensive with the dynamic effects of the explosion.
The idea prevalent before the mine had been explored, that the Cecile fire was the cause of the explosion, was not borne out by the facts observed, which it will be convenient to describe here. As before stated this fire had been discovered between the 6th and 7th Alarch in a return airway through goaf or old workings in the veine Cecile, at a point dear No. 3 pit between the levels 280 and 326 metres. Between that time and the morning of March 10th, the fire had been enclosed by means of stoppings as shown on Plate VII. The seat of the fire was in an area of old goaf adjoining, and to the S.W. of No. 3 shaft pillar of solid coal. The stoppings Nos. 1 to 5 on the level 280 were in narrow roads in the shaft pillar, No. 3 stopping being in an entrance to stables ; these stoppings were of brick and cement, some with stowing behind. Stoppings Nos. 6, 7 and 8, in the return air road, above level 326, were of stowing with dry stone walls in front. The stoppings were completed during the night before the explosion.

Of the five stoppings on the return side at level 280, Nos. 1., 4, and 5 were found to be intact and undisturbed, -whilst Nos. 2 4nd 3 (which were simply brick walls) instead of being blown outwards, as would have been the case if the fire had caused the explosion, were clearly blown inwards or towards the fire. The direction in which these stoppings were blown was consistent with other indications of force coming up No. 3 shaft and an adjacent staple, which will be described later. The lower or intake side stopping No. 8, the only one which could be reached on that side, was quite undisturbed, with no indications of any explosion immediately outside it; and, further, the indications of force observed on the Cecile level 326 and the adjoining South bowette were opposed in direction to force coming from this stopping. From these facts and a careful consideration of all the circumstances, we are clearly of opinion that this fire was not the cause of the explosion.

We have heard some discussion as to a theory that gas distilled by the fire was drawn through fissures in the strata from the seat of the fire in the Cecile seam to workings in the Josephine seam more than 40 yards below, and there ignited by a naked light. It is proposed to test this theory by forcing a very odoriferous gas into the place 'where _ the fire was, and ascertaining whether the smell can be detected where it is thought the explosion may have originated in the Josephine seam. We do not attach much importance to this theory.
It may be mentioned here that the importance attached to the danger of coal dust by most English and German mining engineers has hardly been so fully recognised in France, and in some quarters the idea prevailed that dust alone, without gas, was incapable of propagating an explosion for more than a comparatively short distance.

Similar scepticism prevailed in England until repeated experience left no room for doubt that coal dust-alone was capable of causing the most formidable and extensive explosions. The fact is that a radical difference of opinion still exists upon the causes of these explosions. The sound view, we believe, is that nearly all big explosions are chiefly, and in some cases entirely due to coal dust ; but some engineers seem still unwilling to realise that coal dust alone can propagate, much less originate, an extensive explosion.

The fact that the French have attributed less weight than we to the part dust may play in an explosion is no doubt accounted for by the rareness of coal dust explosions in France.
We do not attempt to pass an opinion upon the conduct of the rescue and salvage operations by the engineers of the State or of the company further than to testify to the strenuous exertions with which they are proceeding with the work of recovering the bodies and rehabilitating the mine. The task of judging of their efforts must rest with the commission of M. Carnot and the Courts of Justice.
An examination of the mine has been made by one of us (Mr. W. N. Atkinson) commencing on the 4th May and extending to May 18th, and on a second visit from the 22nd to the 29th June. Eighteen underground inspections were made and most of the accessible parts of the mine examined.
It was found that the explosion had traversed a large proportion of the roads and workings of pits Nos. 4-11, 3 and 2, as judged by the evidences of flame and force observed. The extreme points to which the flame of the explosion had extended, from the east in No. 2 pit to the west in Nos. 4-11 pits, were about 2,800 metres apart, in a straight line. We are unable to estimate the aggregate length of all the galleries traversed by the flame of the explosion, but it would certainly amount to many thousand metres.

In the seam Julie no men were employed at No. 3 pit; at No. 2, seven were killed by afterdamp, having stayed too long at work, while all the others escaped. In Mathilde, at No. 3, a few (six) escaped. In Augustine all (five) died at No. 3 ; no work at the other pits. In Cecile, Nos. 3 and 4, all were killed. In Ste. Barbe a few escaped at Nos. 2, 3, and 4. In Josephine no one escaped at Nos. 2, 3, and 4 except five men (on the 30th March) from Josephine, renversee, south of No. 3. In Marie all died except a few at No. 4, of whom Berthon, who escaped on the 4th April, was one. In Ame and Eugenie some were saved, as also in Adelaide, eight of those who escaped on the 30th March coming from Adelaide, south of No. 3.

Notwithstanding the enormous extent of the explosion, the force exerted did not as a rule appear to have been so extremely violent as has been observed in some English colliery explosions, and this may be accounted for by. differences in the fineness and purity of the coal dust in each case. At Courrieres there was little mechanical haulage, and the bulk of the coal dust on the haulage roads would not be of the peculiar fineness and purity distinguishing the dust which accumulates on the upper surfaces of haulage roads in many English collieries, where coal is drawn at high speeds against strong currents of air.

Generally speaking the roadways and workings were dry and dusty, and so far as our observations extended all the roads and workings traversed by the explosion were, or recently had been, dry and chesty at the time of the explosion. Our investigations could not begin until nearly two months after the explosion, and during the interval some changes had occurred in the conditions of the mine. Many of the main roads forming routes of the explosion had been repaired and retimbered, and about 600 bodies had been 'removed from various parts. Water had accumulated and flooded some of the main roads near the shafts ; and water used at, and steam produced by the fire in the Josephine seam at No. 2 pit, had permeated the workings in that seam and the roads between Nos. 2 and 3 pits, rendering them quite clamp. From these new conditions the appearance and character of many of the roads was different, with regard to dust, to what they were before the explosion.

In endeavouring to arrive at the cause and place of origin of the explosion, the usual course was followed of tracing the direction of the blast by the indications of force left by it. After several days' investigation we arrived at No 3 shaft by the North bowette 250. Here there were strong and clear indications of force having come up the shaft and up a neighbouring staple from below. Large quantities of coal dust had also been blown up, and this was found in heaps on the ground in places favourable to the obstruction of its passage.
We next visited No. 3 shaft at the level of 303 metres, and here again the indications were of force from below. These indications pointed directly to the bottom of No. 3 pit, at the level 326, from which point by way of the North and South bowettes, the workings of several seams were reached, including the lower level leading to the Cecile fire (Plate VII.).

At this time the bottom of No. 3 shaft (bowette 326) was inaccessible through the accumulation of water. Observations made in the bowette to the north and to the south of this shaft indicated force coming towards the shaft from the north and continuing from the shaft to the south.
The next leading indication of force was observed on the Marie level 326 N.E. (Plate VIII.) showing the direction of force to have been towards the north bowette, and by it to the bottom of No. 3 shaft. The Marie level 326 led by way of a cross measure drift to a large district of workings in the veine Josephine, extending from the bowette N. 326 of No. 3 pit to the bowette N. 340 of No. 2 pit, part of which workings are shown on Plate VIII.

In the north-west portion of these workings at the face of a heading in solid coal (marked A on Plate VIII.) a blown out shot was discovered. about the 22nd May, and this we are strongly inclined to think was the point of origin of the explosion, although neither by living testimony, nor as a certain deduction from the indications on the spot, is it possible to prove positively that the blown out shot occurred at the moment of the explosion.
The heading in question, known as the Lecoeuvre gallery from the names of the workmen driving it, was the lower of a pair of levels advancing eastward. At the time of the explosion no one was working in the upper level, called the parallel. The Lecceuvre gallery was about 7 feet 6 inches high (all coal), and about 9 feet wide.

The levels were reached by a pair of rise headings (inclination about 1 in 6), one of which (marked Treuil) was a self-acting incline. On the haulage level at the bottom of the incline were a pair of doors as shown on Plate VIII., and these doors, we were informed, appeared to have been blown in opposite directions as indicated by the darts under them. The incline brake wheel marked on the plan was found as indicated by the dart, 5 metres below its original position. Nearly all the timber in these headings was blown down, and there were falls of roof over nearly their whole extent. The scene at the. face of the Lecceuvre gallery was striking and peculiar. In the face, about 5 feet from the floor, and near the left or north. side of the C2 face of the heading, were the remains of a shot hole, about 20 inches deep. The outer end of the hole was enlarged to about 5 inches in diameter, and the coal forming the inner surface of the hole was shattered. It had clearly been a blown out shot. The hole inclined slightly upward so that the prolongation of its axis met the floor about 8 metres from the face. Inside the hole was some fine coal and coal dust. Immediately under the shot hole was a heap of coal, on which lay the naked bodies of three men, a pick, and some short pieces of timber ; a long post was leaning against the face. Near the face was a wood tub badly broken and partly under a fall.A few metres from the face was a drilling machine, some drills and a wood stemmer, unbroken.
The ventilating pipes were all blown down, and the third pipe from the face, which was opposite the place where the prolongation of the shot hole would meet the floor, was badly broken; the collar connecting the second and third pipes was found inside the second pipe. Nineteen metres from the face under falls was the body of a fourth man, minus an arm and a leg, these detached members being 3 metres further out. There were plentiful indications of flame in the heading in the shape of coked and charred coal dust, and the bodies of the men were reported by the doctor to be deeply burned. he place was very dusty, probably abnormally so, by reason of the use in it, for holing, of a Sullivan machine worked by compressed air. The drawings on Plates IX. and X. are reproductions of photographs taken at the face of the Leceeuvre gallery.

We have not been able to obtain any information as to when the blown out shot was charged, nor of what the charge consisted, but it is thought by the persons best able to judge that the charge would be 400 or 500 grammes (0' 88 or I -1 lbs.) of Favier explosive No. l, in a shot hole about 5 feet long. The only persons who could have given information on these points were , killed by the explosion. The practice with regard to firing shots was that where safety lamps were used the shots were fired electrically by officials, and where naked lights were used, as in the Lecceuvre gallery, the miners fired their own shots by means of safety fuzes. It seems clear, from the positions in which the bodies of the men were found, that this shot was not intentionally fired at the time when the explosion took place, but we think if at all improbable that the shot was one which lid missed fire and was accidentally exploded while being cut out.
On Fig. 2 Plate X. it may be observed that there is a sort of recess about a foot wide in the face of the heading, extending from the level of the shot nearly to the roof, one side of the recess merging into the shot hole. This recess had the appearance of having been formed by pick work, and it might have formed part of the operation of cutting out a missed shot, and its proximity to the shot hole might have caused a badly aimed blow to strike the detonator and so explode the charge.
If the shot hole contained four = cartridges the outer end of the charge, where the detonator is,1i'aially. placed, would be within an inch of the end of that part of the shot hole remaining in the face. If what, five believe to have happened at this blown out shot actually occurred, it would result in the unexpected explosion of a heavy charge of Favier explosive in a hole with little or no stemming.

We are unable to pronounce upon the question whether.Favier explosive No. 1 was a proper explosive to use in such a locality, but experiments made in Westphalia"" proved that charges of 363 and 386 grammes of this powder were capable of causing explosions in air free from gas but containing coal dust; and recent experiments, made in July 1906, at Frameries (Belb-ium), since the explosion at Courrieres, with charges of 400 and 500 grammes, resulted in flames as long as the experimental gallery (30 metres).

When our examination of the mine ended, the investigations of the French mining authorities were not completed, and in particular the Leceeuvre heading had not been thoroughly searched, as it had to be left undisturbed until viewed by the j ustices. It appears that when the air pipes were thorouglly examined, it was found that some of them seemed to have been burst open, and one of them was blown into a large number of pieces, and this led to the idea that the pipes had been destroyed by an internal explosion of fire-damp. The only means we have of forming an opinion on this point is a
Gluckauf.

No. 28, 1897, p. 548. photograph of the damaged pipes (Plate XI.) No doubt the fractures in these pipes will be minutely examined. From their mere appearance, however, we are not able to say that the damage might not have been done by a blown-out shot and subsequent explosion of coal dust.

It is difficult to account for the presence of fire-damp in the pipes (which were laid on the floor), because no trace of fire-damp was found either before or after the explosion. On the other hand, it has been proved experimentally that a blown-out shot of Favier explosive will initiate a coal dust explosion in the absence of fire-clamp.

A difference of opinion as to whether the explosion was initiated by a blown-wit shot or by a local explosion of fire-damp originated by the shot or otherwise, does not in our view interfere with the main conclusion that it was through the agency of coal dust alone that the explosion was propagated throughout the mine.

Of course, the question whether a shot in a dusty place can originate an explosion without the presence of any gas is an important one.
In this connection we may refer to the view of the Royal Commission on Coal Dust, 1894, in which it is said " Coal dust alone, without the presence " of any gas at all, may cause a dangerous explosion if ignited by a blown-out " shot or other violent inflammation. To produce such a result, however, " the conditions must be exceptional, and are only likely to be produced on " rare occasions." Opinions may differ as to whether this was or was not one of those rare occasions, and whether or not some fire-damp was present when the explosions originated.

But the point that is of supreme importance is the consideration, that, however originated, an explosion can travel over the whole extent of a mine by the aid of coal dust alone, and without any gas. And this we have no doubt whatever was the ease at Courrieres. This is a danger against which the use of safety lamps alone will not protect the miner, and it emphasizes the necessity for considering what means can be adopted for preventing or at least localising and isolating explosions of coal dust.

So far as we are aware, all the indications of the direction of force exerted by the explosion point to the Lecwuvre gallery as the place of origin, although, at first sight, certain indications appeared inconsistent with that view. These indications were as follows In the northern part of the bowette north 326, Plate VIII., there were. indications on a number of full tubs of force from south to north, and at the staple marked " Bertia descendent de Josephine a 326 " there were indications that the explosion had gone up it, whereas an explosion commencing in the Lecceuvre gallery and passing by the shortest routes would have gone outward or to the south along the northern part of the bowette, and would have reached the top of the staple before the bottom.
Again, the nearest route by which an explosion beginning in the Leceeuvre gallery could reach the place where the indication of force westward was observed in the Marie level, 326 N.E., was also by way of and from the bowette, whereas the indication was of force in the opposite direction.

An examination of the roads connecting the site of the shot with the N. bowette, the top of the staple, and the Alarie level, 326 N.E., afforded an explanation of these apparent discrepancies in the direction of force ; the explanation was, that sections of these roads were free from inflammable dust, and that, in consequence, the explosion had not followed the shortest route either to the bowette or the staple, but had gained access to both by way of the Marie level, dividing north and south in the bowette at the junction of the roads.

A number of observations were made at places where the explosion ceased, including the places where it stopped on the roads connecting the pits affected by the explosion with other pits ; that is to say, the connections between Nos. 4-I1 pits and Nos. 5-12 pits, between Nos. 2 and 10 pits, and between No. 2 and No. 6 pits. In all cases the arrest of the explosion could be accounted for by the lack of inflammable dust on the roads in question. Samples of such dust as could be collected on these roads were taken for further examination, at points beyond the limits of the force and flame of the explosion. Had the roads connecting the other pits with those traversed by the explosion contained sufficient inflammable dust to propagate an explosion the loss of life would have been largely increased.

In connection with this part of the subject, we were told that the bowette N. 326 of No. 3 pit, the greater portion of which had been traversed by the explosion, had been wet or damp and free from dust. It was certainly damp throughout when we saw it, with water on the floor in some places. The general dampness could be accounted for by the passage of steam from the Josephine fire, and the standing water by falls blocking the gutters. The surfaces of that part of the bowette traversed by the explosion were blackened with the usual coating of dust found after explosions in dusty roads, and at one place coked coal dust was found.

The tubs in No. 3 pit were all of wood, and would drop more coal on to the roads than the iron tubs used in pits 4-11 and 2.
The practice of dropping coal down the staple shown on plate VIII. and marked " Bertia descendent de Josephine• a, 326," might be the cause, in its vicinity, of much coal dust in the bowette, and judging by the amount of coal dust blown up No. 3 shaft and the adjacent staple to the levels 303 and 280, there must have been a great deal of it on the level 326.

The conclusion that the explosion was caused by a blown out shot of Favier explosives lead to serious considerations with reference to the use in fiery or dusty mines of our permitted explosives, the composition of some of which does not differ greatly from Favier No. 1. Points requiring attention appear to be : (1) Whether our present test for explosives requires to be altered; (2) the maximum charges which should be allowed; (3) the minimum length of stemming required ; and (4) the method of dealing with shots which have missed fire.

This explosion emphasizes the risk, now generally admitted to exist in dry and dusty coal mines, of great loss of life in case an explosion is initiated by any means; and in some of our large collieries the loss of life might
equal that at Courrieres if an explosion took place when the maximum number of men are underground. The only certain method of preventing such loss of life would seem to be to render the mines incapable of being the scene of widespread dust explosions by watering or otherwise preventing the accumulation of dry coal dust in the roads and workings.

We are aware that these questions are occupying the attention of. a Royal Commission on Mines and also of a Departmental Committee. For these reasons we deem it unnecessary here to offer detailed observations on the subject.
The Courrieres explosion extended through the workings of three pits, a fact which raises the question whether it is advantageous from the point of view of safety to connect the workings of different pits. The chief object of making the connections at Courrieres was probably for purposes of ventilation and haulage, and to obviate the necessity of sinking two shafts for each separate winding plant. At the same time we believe that the connections were regarded as conducive to safety by affording additional means of escape in case of accidents.

In the case of explosions the utility of extra shafts as means of escape will depend largely on whether the roads approaching them are traversed by the explosion or not, and this could be prevented so far as coal dust is concerned by keeping the roads clear of dust. At the same time roads connecting different areas of workings are liable to become channels for conveying afterdamp into workings which might not otherwise have been affected by an explosion ; and they might also convey smoke in cases of fire. Where distant shafts are connected and are intended to be available as emergency exits, all the officials and a proportion of the workmen should be made acquainted with the roads leading to them, and direction boards should also be placed along the routes.

In the discussion in the Chamber of Deputies on the 3rd April, attention was called, as an alleged danger, to the fact that in the mines of the Pas de Calais and the Nord it was not required to stow or fill up the worked out and abandoned parts of the mine, as was obligatory in other French mining districts. We saw no evidence that the absence of this precaution had any bearing on the explosion. There are no statutory regulations on the subject in this country and the systematic and complete filling up of the goaf and abandoned workings is little practised, save in cases where the working operations produce sufficient refuse for the purpose, and even then it is some times brought out of the pit as the cheapest way of dealing with it. The system of filling up the goaf presents several 'advantages ; it prevents the accumulation of noxious gas in the abandoned and unventilated spaces, it supports and steadies the roof at the working faces, reduces or eliminates liability to spontaneous combustion and reduces surface subsidence and damage. The method of packing the goaf with material from the surface, flushed in by water through iron pipes, is being introduced at some of the collieries of the Pas de Calais, and we visited the mines of Lievin to see a plant estimated to cost 40,0001. when completed, which is being installed to carry out the system at one of the pits.

We are indebted for the photographs in the Leceeuvre Gallery to Mr. A. M. Henshaw of the Talk-o'-the-Hill Colliery, who, with the permission of the Company, came over and took them. Mr. Henshaw's experience in explosions and fires in collieries rendered his assistance of great value to us.

In conclusion we desire to express an appreciation of the great help we have received in our inquiry from the Ministry of Justice, the State engineers, and the engineers and officials and workmen of the- Company. All have done their best to help us with that readiness and courtesy that are proverbial in France.

CUNYNGHAME. W. N. ATKINSON.

NOTE.-Since our report was written, the report of the Committee presided over by M. Carnot has appeared. It will be found printed in the French

" Official Journal " of August 11th. The reference to the Committee was as to the conduct of the engineers of the State and Company during the rescue operations that succeeded the explosion.

The Report acquits the engineers of all blame, and bears testimony to their exertions.
The reports of the officials of the Courts of Justice have not yet appeared, except that of the parquet at Bethune by M. Baudry, which acquits the State engineers of all blame in the rescue operations, and detailed medical examination of the bodies has established the fact that of the bodies that have been recovered none, so far as can be ascertained, had survived the day of the catastrophe.