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Owing to difficulties in preparing a site for the driving engine, many weeks elapsed before the fan was put to work. In fact, next to nothing had been done when I returned to the island on the 24th of May. I again tested the air, but did not think it prudent to descend, especially as an obstruction in the shaft midway between the 130 and the 141-fathoms levels prevented the kibble from being lowered any further. However, the visit was not thrown away, as on the following day I attended the inquest which had been adjourned by the High Bailiff from Wednesday, the 12th of May, when he simply took formal evidence for identifying the bodies and medical evidence as to the cause of death.

At the adjourned inquest, evidence was given by Captain Reddicliffe, myself, Mr. Williams, and one of the miners, and our examination occupied no less than eight hours. My most important duty was communicating the result of the analyses of two samples of gas which Mr. Williams had obtained just above the 130 level, at the risk of his life, in the manner already described. Dr. John Haldane, F.R.S., Lecturer in Physiology. University of Oxford, to whom the samples had been submitted, had made the following report to you :—

Although, after the statement of Dr. Miller and the appearance of the corpses, there was no doubt about the cause of death, it nevertheless was extremely satisfactory to find such ample confirmation by Dr. Haldane, and it is worthy of remark that upon no occasion, as far as I am aware, has a sample of such a terribly poisonous character ever been taken in a mine.

The whole of the evidence confirmed me in the opinion which I had formed on the very first day I heard of the accident — that it resulted from an underground fire.

It was found on testing the air, day after day, by lowering mice and candles from the surface, that the atmosphere of the mine was improving gradually under the influence of the natural ventilation, and on the 7th of June it was considered that the descent to the 130-fathoms level could be made with perfect safety. A party of men went down the mine and sent up the last body — that of Robert Kelly.

Owing to official work at Petty Sessions in Wales and in the southern portion of my district, my next visit to the island was not until the 16th June I was then fortunate enough to be accompanied by Dr. Haldane, who made a visit at his own expense in order to investigate the circumstances of such an important disaster from the poisonous gas. with which, more than any other scientific man, he is so thoroughly familiar. A very stormy passage prevented our reaching the mine until late in the afternoon, and by that time Mr. Williams and Captain Kewley had been down the mine and had discovered the seat of the fire. They then accompanied Dr. Haldane, Dr. Miller, Captain Reddicliffe and me to the 130-fathoms level, and at a point about 630 yards north of the shaft we found that the level was completely blocked by rubbish, which had fallen from workings above, as the supporting timbers had been destroyed by fire. The pieces of charred timber left no doubt about the origin of the disaster.

A sample of the air taken by Dr. Haldane gave him the following results on analysis :—

Carbonic acid gas	0.64
Oxygen	20.17
Nitrogen and Argon	79.19
	100.00

No trace of carbon monoxide could be detected in the sample.

On the following day we all attended the inquest. which again lasted many hours. Evidence was given by Captain Kewley, Dr. Haldane, myself, Mr. Williams, and some of the miners. After a careful and lucid summing up by the High Bailiff, the jury retired to consider their verdict, and eventually delivered it in the following form:—

"That the deceased met with their deaths by breathing air impregnated by carbon monoxide, which was generated by the burning of timber in the 130-fathoms level, but we have no evidence as to how the timber was ignited. We would strongly recommend the adoption of the means suggested by Dr. Foster for the prevention of the recurrence of such a lamentable event, namely, the use of uninflammable roof-timbers and supports; the mechanical means for the raising and lowering of the men, but especially the inspection of the mine prior to the men commencing work on Monday morning. We are glad to learn that the fan now being put up is to be a permanent erection, and hope that it will become a further improvement to the ventilation of the mine. We also recommend the periodical inspection of the upcast shaft, not only by the officials of the mine, but also by H.M. Inspectors. We wish to express our profoundest sympathy with the families of the bereaved, and our high appreciation of the ready and generous response to the appeals which have been made in behalf of the Relief Fund. We would also take this opportunity of placing on record our great admiration of the courage and perseverance displayed in the rescue of the men and the bodies by Inspectors, by the Captains, and also by the men who formed the relief parties. And lastly, we would thank you, Mr. Coroner, for the patience and urbanity which you have displayed in conducting this very painful and difficult inquiry."

With reference to the recommendation about the "periodical inspection of the upcast shaft, not only by the officials of the mine, but also by H.M. Inspectors," I beg leave to remark that there is no such thing as an upcast shaft at the Snaefell mine in the ordinary sense of the term ; but, as will be seen from the section (Plate I.), there are a set of intermediate shafts (winzes) connecting the various levels, which form a return airway. As a matter of fact, I had climbed through these various intermediate shafts a few years ago, and Mr. Williams would have proceeded to the surface by the same route on the 7th of May, if his inspection of the workings had led him to believe that there was any necessity for so doing.

Though Professors Dewar,³ Tilden⁴, and Bedson⁵ have discovered that carbonic oxide occurs occluded in certain rocks and minerals, the gas has never, I believe, been found as a natural constituent of the atmosphere of mines. It was evident, therefore, from the first, that I had to seek for some artificial source of the poison when investigating the accident, and I think that it is now perfectly certain that the deaths of the twenty victims of the Snaefell disaster were due to carbon monoxide, produced by timber burning in the mine. The next point for consideration is how the timber became ignited. Before the workings could be entered, I suggested two possible explanations (1) A lighted candle stuck up against one of the timber supports; (2) The spontaneous combustion of' cotton waste impregnated with oil, which had been in use by the men who were working rock drills.

As the inspection of the mine revealed the fact that the seat of the fire was at the 130-fathoms level, where men had been engaged in putting in fresh timber, and not in the 171-fathoms level, or in the "stopes" above it, where machine drills were being employed, I naturally at once abandoned the second theory, and I feel convinced in my own mind that the first is the true solution of what was thought by some persons to be a mystery.

The timber in parts of the 130-fathoms level is very dry, and would easily take fire. It will, then, be asked how the ignition of the timber could escape the knowledge of the men employed at the place.

To answer this question one must explain a common practice of miners. When his candle, held in its clay socket, is nearly burnt out, the workman very frequently sticks up the end against the side of his working place. whether timbered or not, takes a fresh candle from his bundle and lights it at the flame of the old one ; he then blows out the flame of the candle-end, or puts it out with his fingers, with the intention of using it as a "snuff" for igniting the fuse of some future shot. Careless miners may sometimes, leave a candle-end to burn away of itself, whilst in other cases the snuffing out may be imperfectly performed and the wick may go on smouldering, and eventually ignite inflammable material with which it is in contact. It is quite easy, therefore, to account for the ignition, and some facts which I extracted at the inquest fully confirmed me in my belief. In answer to my question, "Have you ever known timber used in a mine take fire accidentally from a candle being left near it ?" Captain Reddicliffe stated that he thought he could recollect no less than five cases of the kind — three in Laxey mine and two at other mines.

Once started upon a timber prop, the fire would naturally spread to the adjacent supports. and no doubt it burnt well and thoroughly for a time, as long as plenty of air was available; but when the combustion of the supporting frames so weakened them that they gave way under the weight of the waste material lying upon them and caused a block in the level, the condition of things was somewhat altered. The timber was then burning in a sort of cul-de-sac and did not get all the oxygen necessary for the perfect combustion of the carbon ; the result was that carbon monoxide was generated in addition to carbon dioxide.

It is rather startling to find how small a quantity of timber need be burnt to pollute to a dangerous extent the passages of a mine. According to Mills and Rowan⁶ air-dried wood may be considered as consisting of —

40	parts of	carbon (inclusive of 1 part ash),
40	,, ,,	oxygen and hydrogen in the proportion in which they unite to form water,
20	,, ,,	hygroscopic water.

Taking the weight of a cubic foot of larch, which was the kind of timber employed at Snaefell, at 34.5 lbs.⁷ the quantity of carbon in it will be

12 parts by weight of carbon combining with 16 parts by weight of oxygen will produce 28 parts by weight of carbon monoxide. Therefore, l. cubic foot of larch will produce

of carbon monoxide. At a temperature of 60° F., and under a barometric pressure of 30 inches, 1 cubic foot of carbon monoxide weighs about 520 grains. 31 lbs. of carbonic oxide will therefore occupy 417 cubic feet of space. Taking an ordinary mine tunnel or level as being 7 feet high by 5 feet wide, each yard of length would contain 105 cubic feet, and therefore it is easy to see by calculation that 417 cubic feet of carbon monoxide would furnish one per cent. of the contents of a gallery about 400 yards long. Of course one per cent. of this noxious gas is quite sufficient to cause almost immediate loss of consciousness, followed speedily by death.

The total capacity of all the levels, shafts, and excavations in the Snaefell mine was stated in evidence at the inquest to be a little over a million cubic feet, therefore 25 cubic feet of timber contain carbon enough to produce sufficient carbon monoxide to give an atmosphere with one per cent, of the noxious gas all through the mine.

I have not taken into account the alteration in the volume of the gas which would be caused by differences of temperature and pressure, because these would not affect the gist of my statement that a very small fire may suffice to produce very disastrous results, unless the air currents traversing the workings are sufficiently strong to sweep out the foul gases as quickly as they are produced. At Snaefell the block in the level produced by the rubbish falling when the supporting frames were burnt away, stopped the air current in that part.

I will now for a moment consider the question of carbon dioxide.

Calculating in the same manner as before, we find that the perfect combustion of one cubic foot of larch would produce 49.335 lbs. of carbon dioxide. As one cubic foot of carbon dioxide, under the same conditions as before, weighs about 820 grains, the above quantity of' 49.3 lbs. would occupy a space of 420 cubic feet. A hundred cubic feet of larch would give 42,000 cubic feet of carbon dioxide. or enough to impregnate a million cubic feet to the extent of four per cent. therefore we see that the combustion of 125 cubic feet of timber might have added sufficient carbon dioxide and carbon monoxide to bring the whole atmosphere of the mine into the condition of the poisonous sample so often referred to, whilst its noxious properties were strengthened by the exhaustion of the life-sustaining oxygen. However, it is not likely that the whole of the mine was ever full of such an atmosphere, and the combustion of' a very much smaller quantity of timber than that which has been mentioned would have sufficed to produce the poisonous atmosphere in the 130-fathoms level and in the shaft. If we take a timber supporting frame (sett) in a level, consisting of two side props (legs), each measuring 6 feet 6 inches each in length and 9 inches in diameter, and a horizontal beam (cap or head-tree) 6 feet long, and of the same diameter, we have at once more than 8 cubic feet of wood. The frames were placed very close to each other; in fact, there were nearly three to the yard. In addition, the covering pieces of timber placed upon the "caps" were four inches thick, and were again overlaid by other timber, so that one may safely assume that in each yard of level there were more than 35 cubic feet of timber. An examination of the 130-fathoms level has shown that the fire extended for 11 yards along it, because it is blocked for that distance. Under these circumstances, though the extent of the fire may not have been very great, still there is evidence of a sufficient amount of burning to account for the disaster.

It may be a matter of surprise to some persons that the miners should have gone to their fate without any suspicion of the danger ahead. If the fire had taken place on any day except a Saturday. the men of the afternoon shift would probably have become aware of it before it had attained very dangerous proportions, and before the lack of oxygen had been the means of causing the generation of the supremely poisonous lower oxide of carbon. The intervening Sunday, when no one was down the mine, gave time for the gases to cool and the odour of burning to subside, and consequently warnings were lacking which would have been present if the mine had been entered sooner. Besides, it must not be forgotten that the miner usually considers that his candle is a sufficient indicator of the state of the air if it burns dimly, he becomes suspicious; if it goes out, he feels that there is danger. At Snaefell the candles continued to burn brightly, and though some of the men evidently noticed a little smell, and a feeling of warmth in the air, there was nothing to make them apprehend that their lives were in jeopardy, until they began to be overcome. Probably no miner in the Island had ever heard of carbon monoxide and its noxious qualities.

A question often asked is, "Why did not the men start to climb up the ladders the moment they began to feel the effects of the poison ?" This is easily answered by those who have suffered from its effects and escaped with their lives. Carbon monoxide is a most insidious enemy, for, whilst it is easy to go on descending ladders while inhaling the poisonous atmosphere, the limbs seem to be incapable of action when the exertion of climbing upwards has to be encountered. The position in which the bodies were found confirms this view of the case.

2 A duplicate determination also gave 4.22 per cent.
3 "Recent Researches on Meteorites." — Proc. Roy. Inst., Vol. xi., London, 1886, p. 546.
4 "On the Gases enclosed in crystalline Rocks and Minerals." — Proc. Roy. Soc. , Vol. lx., 1897, p. 453. Since my report was written, I find that Prof. Ramsay and Mr. Travers, in their paper upon Fergusonite. state that a small quantity of carbonic oxide is given off by the mineral gadolinite when heated (Proc. Roy. Soc. , Vol. lxii., 1897, p. 329), whilst Behrens notes the occurrence of the gas in the coal of Upper Silesia ("Die Kohlenstaubgefahr und ihre Bekampfung," (Gluckauf, Vol. xxxiv., 1898, p. 316).
5 "A Contribution to our Knowledge of Coal Dust." — Trans. Fed. Inst. Min. Eng. , Vol. vii., 1893 — 94, p. 28.
6 Fuel and its applications, London, 1889.
7 Pocket book of Engineering formulae by Molesworth, 22nd. edition, 1888, p. 18; 34.5 is the mean of the two values given. Karmarsh, quoted by Mills and Rowan (op. cit. p. 7) gives 0.565 as the specific gravity of air-dried larch, which is equivalent to 35.3 lbs. per cubic foot.