[From 'Investigation of Mine Air, 1905]

APPENDIX.

THE EFFECTS OF CARBONIC OXIDE IN CONNECTION WITH AN UNDERGROUND FIRE AT SNAEFELL MINE.

THE accident here referred to occurred in May 1897. Sir Clement Le Neve Foster was at that time Chief Inspector of Mines for the district within which the accident occurred, and it was thus his duty to go to the mine and report upon all the circumstances.

Snaefell lead-mine is situated on the flank of the mountain in the Isle of Man from which it takes its name. It is a small and somewhat primitive mine, only employing about fifty men at the time of the accident. As is shown by the sections (Plates I. and II.), the mine is worked by a main shaft, which follows the dip of the vein, and was 171 fathoms deep. The shaft, which is rectangular, is divided into three compartments, the middle one being the ladderway, and those on either side being used respectively for winding ore, and for the pump and the compressed air pipes. The ore was wound up in a rough wooden bucket or " kibble."

In the main the ventilation was " natural," being due to the higher temperature underground than above ground. The general tendency of the air-current was down the shaft to the bottom of the mine, and up through the various winzes (intermediate shafts) to the adit level. The open end of this had been connected to a sloping wooden chimney on the hillside, by which means the draught was increased. The mine had been officially inspected three days before the accident, and the ventilation was in its normal state, though on several previous occasions it had been found to be defective.

The time spent upon the ladders by the young and active men was about a quarter of an hour in descending and half an hour in ascending. The older men would take longer.

The following account of the accident and subsequent exploration of the mine is reprinted from the official Report.¹

Accident, and Rescue of some of the Miners.-A little after 6 a.m. on Monday, the 10th of May, the morning shift, consisting of thirty-five men, entered the shaft and began their descent down the ladders. Shortly afterwards several men came to the surface in an exhausted condition, saying that the mine was full of some foul gas, which so deprived them of their strength that they could scarcely climb the ladders. These facts were at once reported to Captain Kewley ; after sending to Laxey for assistance, he immediately descended the shaft with the object of ascertaining the true state of affairs, and of rescuing the men below, who were stated to be more or less overcome by the noxious gases. He met a few men almost dead-beat, trying to make their way up, and between the 45 and the 60-fathoms level he came upon others, still alive, but quite unconscious.

With the object of improving the atmosphere of the mine, he had holes punched in the pipes conveying compressed air to the boring machines, and this gave some relief.

If one tries to imagine the exact condition of affairs in a shaft such as has been described, it is evident that the task of the rescuers was no easy one. Persons unaccustomed to mining can best understand the state of the case by picturing the shaft as a rectangular well, having a ladderway in the middle (Plate II.). The unfortunate men had to be dragged up from platform to platform with the aid of ropes, through the "manholes," which measure only 22 inches by 19 inches, whilst the rescuers themselves were breathing a poisonous atmosphere, and beginning to feel its paralysing effects.

I have mentioned that ore and waste rock are drawn up the shaft in a bucket (kibble) ; but in cases of severe accidents, a special receptacle is used in its place for conveying the injured persons to the surface. It is a rectangular box six feet long, and just deep enough and broad enough to take a man. This was called into requisition a little later, and, with the aid of volunteers who had come from Laxey mine, three of the survivors were successively put into it and dragged up the shaft by the winding engine.

The work of rescue proceeded under great difficulties until five 0?clock in the afternoon, when James Kneale, the last survivor, was brought to the surface. By this time the rescuers themselves were thoroughly exhausted, and barely able to climb the ladders. Captain Kewley, whose pluck has in no way suffered from his sixty-five summers, had gone down no less than ten times, risking his own life again and again, in the hope of bringing succour to his men.

Dr Miller, of Laxey, on hearing of the disaster, immediately proceeded to the mine and gave medical aid to the sufferers, several of whom were still unconscious on reaching the surface.

Fortunately for all concerned, my assistant, Mr Williams, was still in the island ; and, upon receiving notice of the disaster through the foresight of Mr Samuel Harris, High Bailiff of Douglas, he hastened to the mine, ~which he reached about six in the evening. In the hope of finding further survivors underground and being able to save them, he at once organised another rescue party with Captain Kewley, and descended the shaft to the 74-fathoms level, passing three dead bodies. Mr Williams and a miner named Frederick Christian then made their way nearly to the 100-fathoms level, passing other dead bodies, some of which impeded their progress. The obstruction of the manhole just above the 100-fathoms level by three bodies was so great, that they decided to proceed no further ; and it is fortunate that they did so, for on commencing their ascent, they found that their strength was failing them, and that they had a difficulty in climbing the ladders. In time they reached the 60-fathoms level, and rejoined Captain Kewley and the rest of the rescuing party, who had commenced the ascent and were complaining of weakness and of inability to climb. It was then that Mr Williams applied a remedy, in a fashion hitherto untried in mining accidents, as far as I am aware.

On hearing at Douglas that the accident was probably due to foul gases, Mr Williams tried to procure some cylinders of compressed oxygen. As none could be obtained, he thought that possibly he could effect his purpose by generating the health-giving gas on the spot, and he bought about a pound and a half of potassium chlorate. This he carried with him down the mine, and made use of it while he and the rest of the rescue party were -,waiting to commence their ascent from the 60-fathoms level. He set light to a heap of newspapers on the floor of the level, and kept throwing the potassium chlorate, little by little, on to the fire. On leaning over it and inhaling the fumes, the party experienced decided relief, and to some extent regained their strength. I imagine that the deflagration of a portion of the chlorate furnished heat enough to cause another portion to give off its oxygen ; but, be the explanation what it may, I am assured by Mr Williams and Captain Kewley that the improvised remedy was unquestionably of service in enabling the rescue party to reach the surface. By this time they had been forced to the conclusion that no one remained below alive.

Before going underground, Mr Williams had telegraphed a brief notice of the disaster to me ; but, unfortunately, I was engaged officially at Newhaven, and the telegram did not reach me till after the last train had left for London. I was consequently obliged to defer my departure until the following morning, and then it was impossible for me to reach Liverpool in time to catch the mail steamer leaving that port for Douglas. I was unable to start from Liverpool until the morning of the 12th.

Recovery of the Dead Bodies.-After the last unsuccessful attempt to find and rescue any possible survivors, a consultation was held between Captain Kewley, Captain Reddicliffe, Mr Williams, and Dr Miller, and it was thought desirable to bring up the corpses from underground as soon as possible, as the work of removal would certainly become more difficult, sickening, and noxious each day it was delayed. On this account Mr Williams again descended the mine with a party of men, and was engaged till eleven o'clock at night in sending three bodies to the surface.

Early on the following morning the work of recovery was continued, under the superintendence of Mr Williams, as Captain Kewley was suffering from the effects of the poisonous atmosphere in the mine on the previous day besides having ample work to do in superintending the disposal of the bodies as they were sent up to the surface. The working parties had further the aid and advice of Captain W. H. Kitto, the manager of Foxdale Mine, and my friend Mr H. Wynne-Finch, who happened to be staying with him when the news of the disaster arrived ; they at once proceeded to Snaefell, descended the mine, and threw themselves into the work energetically.

Early in the afternoon, Mr Williams was so exhausted by his exertions, that he became unconscious for a few minutes, and had to be sent up to the surface in the "box." By this time ten bodies had been recovered, making, with the three brought up on the previous day, thirteen in all. Work was then suspended for the day. About six o'clock in the evening, a party of volunteers from Foxdale Mine, .,summoned by telegram from Captain Kitto, reached Snaefell, and would have descended at once if they had not been told that their services would not be required until the following day.

My other assistant, Mr Jones, who had started from Chester as soon as he received telegraphic instructions from me, reached Laxey in the evening.

On the Wednesday morning a party of volunteers, headed by Mr Williams and Mr Jones, descended the mine, and recovered five more bodies, which were found on different platforms near the 115-fathoms level, some above and some below.

By this time, they had descended as far as the platform immediately above the 130-fathoms level (CD, Plate Ill, fig. 1). One of the miners kneeling upon this platform put his candle through the " manhole " in order to look for the last body, when he found that it was at once extinguished. Knowing the importance of ascertaining the exact nature of the poisonous gas, Mr Williams sent a note to the surface asking to have some bottles, filled with water, and well corked, sent down to him for the purpose of securing samples for analysis. When the bottles arrived, he stood upon the second rung of the ladder below the platform, and, keeping his head well up, he held one of them under the platform, allowed the water to rim out, and re-corked it. A second sample was obtained in alike manner, but while he was emptying the water from a third bottle, he suddenly, and without any warning, became unconscious. There is no doubt that he inhaled a big whiff of gas which came through the " manhole " when disturbed by the operation of taking samples. The effect was instantaneous, but it must be recollected that his blood was already affected by his having been down the mine for some hours. As he knew that he was running some risk, he had wisely taken the precaution to put a rope round him before beginning his dangerous task, and it is most fortunate that he did so, for otherwise it is almost certain that he would have lost his life. Mr Jones and some miners who were holding the rope dragged him up from platform to platform, for a total distance of 80 feet, still in an unconscious state ; and their work was not accomplished without difficulty, for they were feeling the effects of the poisonous atmosphere, and had only just strength enough to lift their living burden. On reaching the 115 fathoms level, Mr Jones held his colleague's mouth to a hole punched in an air-pipe, through which a strong current was issuing and worked his arms backwards and forwards in the manner recommended for the apparently drowned, and before long he was rewarded by seeing signs of life. Mr Williams was then at once sent up in the " box," and on arrival at the surface he was brought round by Dr Miller, who injected ether subcutaneously.

Mr Jones managed with difficulty to climb to the top with the rest of the party. There is no doubt that by his presence of mind, under very trying circumstances, he saved Mr Williams' life.

Undeterred by Mr Williams' narrow escape from death, Captain Kitto descended the mine in the afternoon with Mr Wynne-Finch and a party of volunteers from Foxdale, with the object of endeavouring to recover the last body, leaving his assistant, Captain Lean, to direct matters at the surface if necessary. They penetrated as far as the platform which Mr Williams had reached when he took his sample, and reported that they saw a body upon the landing some 10 feet below it. While one of the men was punching the air-pipe, in order to improve the ventilation, Mr Wynne-Finch became unconscious, and ~vas sent to the surface in the "box."

Captain Kitto and his men then ascended the ladders, all feeling more or less the effects of the poisonous atmosphere which they had been breathing.

Travelling by the earliest possible steamer, I was not able to reach Douglas until the afternoon of the Wednesday (12th of May), and on proceeding at once to the mine I found Dr Miller, who took me to see the eighteen corpses laid out in the carpenter's shop. He pointed out the signs of poisoning by carbonic oxide, telling me also that these had been more apparent on the Monday and Tuesday. I was also able to congratulate Mr Williams upon his escape and hear from him and Mr Jones some details concerning the condition of the mine. I then went to see my friend Mr Wynne-Finch, who was lying down in his mining clothes, still feeling bad. Later on he was brought down to the inn at Laxey and was put to bed with hot bottles. The next day he was sufficiently well to return to Foxdale.

As the men who had been underground were tired or exhausted, and as there was nothing to be gained by an immediate descent, I postponed my visit underground until the following day. I then considered it my duty to test the air very carefully for fear of risking any more lives. I had come to the conclusion from Mr Williams' first telegram, and from newspaper accounts, which told me that the disaster was caused by fire or foul gas, that probably carbon monoxide was at the bottom of the mischief, and therefore in passing through Liverpool I had bought a supply of mice, with the object of employing them as indicators of the poison in case it should still be present.

A mouse was put into an improvised receptacle made from the revolving part of its cage, and this was attached to the " clevis " or spring. hook of the winding rope, whilst a lantern and lighted candles were placed inside the kibble. By the aid of this testing apparatus it was easily ascertained without any risk that the air was not bad as far as the 115 fathoms level, and that it became poisonous and deadly at the 130. The mice showed precisely the same symptoms as human beings ; for, if not completely dead on arriving at the surface, they had lest all power in their legs, whilst pinkness in the snout recalled the pink lips of the dead bodies of the unfortunate miners. I then decided to descend the mine and learn by further personal examination the precise condition of affairs. Accompanied by Mr Williams, Mr Jones, Captain Kewley, and several miners, I went down the ladderway as far as the 115 fathoms level, and on descending deeper took the precaution to test the air with a mouse and candle before going below each platform. By means of a string I lowered the cage, with the mouse inside and the candle affixed by a lump of clay (see fig. 40), from one platform to the next, and left it for a couple of minutes before drawing it up. Testing carefully in this manner from stage to stage, we arrived all right at the bottom of the fourth ladder (AB, Plate III., fig. 2); but when, standing upon the platform at the foot of this ladder, I lowered the mouse to the fifth, I found that the light went out and that the little animal showed signs of much distress. The air was evidently worse than it had been on the previous day, for then a light would burn brightly on the platform, although it was extinguished below. On Thursday, the day of my visit, there was very bad air above the platform. One of the miners begged me to be allowed to go down with an airhose in his mouth ; 'out of course I refused, saying that I was responsible, and that no one should go down lower. We all climbed up again without difficulty ; though, after an hour at the surface, I began to have a violent pain across the forehead which lasted some time.

In order to improve the ventilation of the mine, I had a fire lighted at the bottom of the wooden chimney, and I was glad to see that it created a good draught,

On the following day my tests made from the surface showed me that the level of the bad air in the mine had not gone down as I expected. I therefore concluded that some of the ventilating doors, which I had been told were shut, must be open. Captain Kewley offered to send down men to see, but I thought that it was better that I should go myself. Mr Williams, Mr Jones, and Captain Kewley came down with me to the 100 level, and we found two doors open. These I helped to shut, and we came up, hoping to find a great improvement on the morrow.

On the Saturday morning my tests with mice proved that things were much in the same condition ; and it then seemed to me probable that the door at the 130-fathoms level was open, allowing the air going down the main shaft to escape through this level to the succession of intermediate shafts which formed the upeast, -Without going to the lower levels at all. I was of opinion that this door should be closed if possible, and there was naturally a desire on all sides that the last body should be brought up.

Mr Williams, Captain Kewley, Captain Reddicliffe, and I, with a party of miners, went down all right to the 115-fathoms level; and before descending any further I tested the air, by lowering a tame rat in a cage, from platform to platform. leaving most of the miners at the 115, Mr Williams, Captain Kewley, Captain Reddicliffe, 1, and

Henry Clague reached the fifth platform (CD, Plate III.) in safety, from whence, when I lowered my testing apparatus with its candle alight, I could see the body of the poor miner, lying in the position described by the Foxdale men. Just at the level of the body, the candle went out. I let the cage with the rat remain down five minutes by my watch, and when brought up it was not dead, though visibly affected. Captain Kewley and Clague said they would go down and get up the body. I had to tell them plainly that they should do no such thing. No doubt it looked easy, for the body was not more than 10 feet below us. I was firm in refusing permission, but said that I thought we might grapple for it easily and bring it up in a very few minutes. One of the men who was higher up came down with the grappling iron, and, in order to use it more conveniently, he pushed aside the short ladder leading from the platform CD to the 130 level. Moving the ladder seems to have disturbed the body of gas, for almost immediately afterwards Captain Kewley said he was feeling ill, so I shouted, " All up at once." We all climbed to the 115 level, where the "box" was in readiness. Captain Kewley was put into it, and we signalled to have him wound up. Those who had been as far down as the platform CD were decidedly affected by the poisonous atmosphere, and as they felt they could climb no higher, they sat down in the 115 "lodge " or "plat," that is to say, the enlargement of the mouth of the level where it joins the shaft.

The miners who had remained at the 115-fathoms level, or had descended but little below it, started off by the ladders, and in time reached the top of the shaft in a somewhat exhausted condition. In the meanwhile the " box " in which Captain Kewley was being raised to the surface stuck in the shaft, owing to a link of the chain, by which it was attached to the winding rope, getting caught between two of the planks in a defective part of the wooden trough up which it was sliding. The "box" would go neither up nor down, and poor Captain Kewley was kept in this trying position for about an hour. At last his son went down with some men and set the " box " free, and another party came to the 115-fathoms level to rescue those -,who were unable to climb. The "box" was sent down to that level, and one after another we were brought to the surface. After this misadventure it was evident that it would be unwise to venture down the mine again until the ventilation had considerably improved.

Further Examination of the Mine and Inquest.-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, ill 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 :-

" OXFORD, May 19th, 1897.

Sin,-I beg to report as follows on the articles transmitted to me for examination in connection with the Snaefell disaster.

" The articles which had been forwarded to the Home Office by Dr Le Neve Foster, H.M. Inspector of Mines, consisted of two dead mice ' and two samples of air contained in bottles. The bottles were closed by corks, which had been sealed and were found to be perfectly air-tight.

" The first mouse examined was labelled as follows :-'Snaefell Mine, No. 1, 13th May. Mouse lowered into the mine in a kibble as far as 130-fathom level, came tip alive, but legs paralysed ; killed on reaching the surface.'

" The blood on dilution with water was found to have the pink tint characteristic of carbon monoxide poisoning. Judging roughly by the tint, I estimated that the haemoglobin was about 80 per cent. saturated with carbon monoxide. An exact determination could not be made, as the light was failing at the time when the articles for examination were received.

" The second mouse was labelled-'Snaefell Mine, No. 2, May 13th, 1897. Mouse taken down into the mine and lowered by me from the platform at the foot of the 4th ladder below the 115-fathoms level to a platform some 25 feet below it. Mouse had suffered and was killed at once.'

" The blood of this mouse had also the characteristic tint of carbon monoxide poisoning. The saturation of the haemoglobin was exactly determined and found to be 78.3 per cent.

"The bottles containing the samples of air were both labelled as follows :-'Sample of air from shaft of Snaefell Mine just above 130 fathoms level, 12th May 1897, C. Le Neve Foster.'

"The composition of the sample in the first bottle opened was found

to be as follows:

The gas in the second (larger) bottle had the following composition

As the second sample was evidently the same in composition as the first, the hydrogen was not determined separately. The carbon monoxide was in each case determined colorimetrically with blood solution, and the hydrogen by passing over a glowing platinum spiral. The carbon dioxide formed by contact with the platinum corresponded exactly to the carbon monoxide known to be present, so that no appreciable proportion of methane or other hydrocarbons can have been present.

" The composition of the sample corresponds to a mixture produced by the combustion of wood or other similar material. Inhalation of air of this composition would produce helplessness (in a man) within about seven or eight minutes at most, and would soon cause death. A candle would not burn in such air, but would just do so on the addition of a third of its volume of fresh air. The mixture would then still be intensely poisonous, and would still be if diluted with four times its volume of fresh air. When diluted with nine times its volume of fresh air it would still be capable of rendering a man incapable of walking.

I am, Sir, your obedient servant, JOHN HALDANE.

The Under Secretary of State, Home Department."

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:-

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

Cause of the Accident and Remarks.-Though Professors Dewar,' Tilden,2 and Bedson 3 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 smoldering, 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 Rowan,' 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 ignite 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.,2 the quantity of carbon in it will be 39 x 34.5 - - 13.455 lbs.

100

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

28 x 13.455

12 = 31.395 lbs.

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 1bs. 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 1 per cent. of the contents of a gallery about 400 yards long. Of course 1 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 1 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 I cubic, foot of larch would produce 49.335 Ibs. of carbon dioxide. As I cubic foot of carbon dioxide, under the same conditions as before, weighs about 820 grains, the above quantity of 49,3 Ibs. would occupy a space of 420 cubic feet. A hundred cubic feet of larch would give 12,000 cubic feet of carbon dioxide, or enough to impregnate a million cubic feet to the extent of 4 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 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 4 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 end 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. ¹

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.

The Mouse as an Indicator of Carbonic Oxide.- It will be seen from what I have already said, that the mice employed as indicators of carbonic oxide did render useful service, as I was able, whilst standing on the surface, to determine, without the slightest risk to anybody, the depth at which the air in the mine really began to get very bad, and to obtain proof of the presence of carbonic oxide in it. A mouse was also of use to me underground in testing the air below the 115-fathoms level from platform to platform, and enabled me to say without hesitation that no one should descend beyond a certain point. However, it gave no indication of the small proportion of carbonic oxide in the air above the highly poisonous parts (Plate III.), either on the Thursday or on the Saturday. It is necessary to recollect that I was using the mouse for the first time, and that consequently I may not have been so keenly alive to the early symptoms shown by the little animal as I should have been if I had practised this mode of testing before ; and, further, I must add that on the Saturday, when my party suffered from carbonic oxide poisoning, I was using a tame white rat, as my supply of mice had become exhausted. The larger the animal the less speedily does it become affected, and if I had used a mouse on the unlucky Saturday, it is quite possible that I should have had earlier indications of danger. On the whole, I must confess that the test with the mouse does not appear to me to be so delicate as supposed by Dr Haldane, or at all. events it is not so delicate in the hand of all unpractised observer.'

Finally, I may remark that the Snaefell calamity, like other disasters all over the world, had a sunny side, for it brought out the nobler qualities of many gallant men. Captain Kewley behaved heroically in leading the plucky band of rescuers, and so did my assistant, Mr Williams. Their names will not be forgotten in the Isle of Man in this generation. I was greatly gratified on learning that their noble conduct had been brought by His Excellency the Lieutenant-Governor of the Island to the notice of the Chapter of the Order of St John of Jerusalem, and that the silver medal for saying life on land had been awarded to each of them. Unfortunately, absence in Canada prevented my attending the meeting at which the medals were presented by His Excellency on behalf of His Royal Highness the Prince of Wales, Grand Master of the Order, and I was unable to express publicly my admiration of the gallantry displayed by Captain Kewley and Mr Williams. Captain Kitto and Mr Wynne-Finch, with a party of men from Foxdale, likewise did useful service ; and my assistant, Mr Jones, will have the satisfaction for the rest of his days of knowing that he saved a comrade's life under very critical circumstances.

Dr Miller's prompt aid to the injured contributed greatly to their recovery, and must not be forgotten.

In obedience to your Special Instructions, I have penned an account of my sensations under the influence of carbonic oxide, and I have collected statements concerning the effects of the gas from Mr Williams, Mr Jones, Captain Kitto and Mr Wynne-Finch. These I have placed in an Appendix. I need hardly say that we none of us desire to parade our experiences in public ; we relate them at your request, in the hope that the account may be of some service to persons exposed to the risk of carbonic oxide poisoning, or at all events be of scientific interest to physiologists.

Footnotes

1 Report to the Home Secretary on the Circumstances attending the Underground Fire at the Snaefell Lead Mine in the Month of May 1897, by C. Le Neve Foster, Esq., D.Sc., F.R.S., one of H.M. Inspectors of mines [C. 8880].

1 "Recent Researches on Meteorites," Proc. Roy. Igist., vol. xi., London, 1886, p. 546.

2 "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 Tiavers, 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 Kohlenstaiibgefahr und ihre Bekdnipfting," Gluckauf, vol. xxxiv., 1898, p. 316).

3 "A Contribution to our Knowledge of Coal Dust," Trans. Fed. Inst. Min. -P,ng., vol. vii., 1893-94, p. 28.

1 Fuel and its Applications, London, 1889. 2 Pocket-book of Engineering Forntitlcp, by Moleswortb, 22u(l 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.

1 It may also appear surprising that the poisonous gas from the fire should have got back into the downcast shaft. The probable explanation is, that the return air was leaking across into the downcast shaft at various levels. In metalliferous mines the extent of this leakage across into downcast shafts is often very great, unless adequate means are taken to prevent it. To give one instance, I found that in the air near the bottom of a downcast shaft in a badly ventilated tin-mine the oxygen was diminished by 0.43 per cent., as compared with 0.48 per cent. near the top of the upeast shaft. The abundant downward current in the lower part of the downcast shaft was thus mostly made up of return air which had leaked across at various levels.-J. S. H.

1 A rat weighs about ten or twenty times as much as a mouse, and would take two or three times as long to react to a given percentage of CO. It is possible, therefore, that the party, when they reached the fifth platform, were from the beginning standing in actually poisonous air on the Saturday, the rat not having been left long enough on that platform to really test the air. A period of fifteen minutes would have been needed for this purpose. It seems more probable, however, that the air down to the fifth platform was at first fairly free from CO, but that the slight rise in temperature due to the presence of the party and their lights produced a current upwards of foul air in the ladderway (the middle compartment) of the shaft. This current probably carried some carbonic oxide up to the 115-fathoms level, to judge by the symptoms of those who were sitting there. Had the air at this point been fairly free from CO, the faintness produced by the exertion of climbing would soon have passed off.

It is undoubtedly the case that a mouse will not indicate by its symptoms such small proportions of CO as were present on the Thursday below the 100-fathoms level. As the mouse test has sometimes been misunderstood, it may perhaps be well to quote the following warning from my description of it in the Transactions of the Institution of Mining Engineers, 1896:- " It should be understood that this test cannot be relied on to do more than indicate the presence of actually dangerous proportions of carbon monoxide, for only a practised observer could detect the outward signs of slight symptoms in a mouse, whereas correspondingly slight symptoms in a man might be very distinctly felt. If the mouse merely shows signs~ of weakness of the legs, there will be danger to a mall, though probably no;ior twenty minutes or half an hour. If the mouse becomes quite helpless and unable to stand, there is danger within a few minutes to a man. If the mouse becomes unconscious and goes into convulsions, there is urgent danger, and not a moment should be lost before retreating."

For detecting very small percentages of CO the mouse must be used in the manner described on page 147. After a recent fire at Dolcoath Mine in Cornwall the whole of the workings ~were explored by this latter method, and the men allowed to return to work in all parts where an examination of the blood of the dead mice showed that appreciable quantities of CO were absent.-J. S. H.