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Accidents in the comstock mines and their relation to deep mining
166
Church~Mi~nln9 Accidents.
[Jour. Frank. Ir~e~
ACCIDENTS IN T I I E C()MSTOCK M I N E S A N D T H E I I ~ R E L A T I O N TO DEE1 ) M I N I N G . e
113), JotlN A. CIrURCH, M.E. A paper read at the Pittsburgh meeting of the American Institute of ~Iining Engineers, May, 1879. Early in the month of August, 1877, a miner in Gold Hill, Neva~lh, " rome the unlucky remark that, according to his observation, that month was usnally quite 5-ee fi'om accidents in the mines. Never" was pre~ge wider from the truth. When the mouth closed twelve mishaps had occurred, killing six and wounding nine persons, and for" the rest of that year the Comstock mitring communities were kept in a ferment by the frequent occurrence of appalling di~sters. There w,'~s a real tidal wave of calamity sweeping over the mines, which has not been repeated since, and according to common report was never known before on the Comstoek. I was much interested in studying the character of these misfi)rtunes, which also aroused concerted action on thepart of the miners, and I have collected a list of the accidents which. took place from July, 1877, to May, 1879. The number in this period of twenty-two months is 101, killing immediately 53 persons and. wounding 70 others. This list is incomplete in every way. All accidents which did not injure persons are omitted, and there are several which were of a threatening kind but ibrtunately (lid no damage to hmnan beings. Probably others have been overlooked which dh[ belong to the category included in my lists. Finally, no efibrt h~s been made to ascertain how many of the wounded died of their wounds, and the nmuber of t:atal casualties include~s only those who died so soon after their injury that their death became a part of the current records of the accident. Many of these accidents belong to the usual classes of mishaps it~ nfines and will receive no extended discussion. Others arc worth examination from their connection with labor in hot mines, deep raining, and other causes intimately dependent on the local conditions off the Comstock. They may all be cl.~ssified under eight general heads : 1. Falls of rock, timber, etc. 2. Tramming. 3. Efthcts of heat. 4. Falls of men. 5. Explosions. 6. tIoisting apparatu,s, 7, O v e r -
Sept,, 1879.]
!67
Ct, trch--Mi'ai~N Accidents.
winding. 8. Miscellaneous. The distribution among these groups in each )'car is shown in the ibllowing summary : .m
1877 1878 6 mos.
(1.) Casualties due to fidls of rock, ice, timber, etc. Number of (x'x~'urrences, Casualties, thtal, Casualties, not fatal, Proportion thtal, 36 per cent. (2.) Casualties in tramming. Nmnber of occurrences, . Casualties, taml, Casualties, not |htal, Proportion ~atal, 12~ per cent. (3.) Casualti(~ due to heat.
1879 4 mos.
8 2
7 4
8 3
7
4
5
4 1
3 0
-t
3
1 1
2 1 1
1 1
8 7 3
7 2 5
7 6 1
2 2
5
6
3
3 5
2 6
5
2 2
3 6
1
,~'calding :
Number of occurrences, Casualties, thtal, C~t~ualties, not thtal, Proportion fatal, 33 per cent. O~erheating :
Number of occurrences, CCsualties, fatal, Casualties, not thtal, Proportion thtal, 73 per cent. (4.) Casualties due to Nlls of men. Number of occurrences, Casualties, fatal, Casualties, not fhtal, Proportion fatal, 62~- per cent. (5.) Casualties due to explosions. Number of occurrences, Casualties, fittal, C~sualtles, not thml, Proportion fitta|, 71 per cent. (6.) Casualties in hoisting. Number of occurrences, Casualties, Ntal, Ca~sualties, not ti~tal, Proportion fatal, 43 per cent.
C hu.rch~Kini~g A eeide~ds.
168
[Jour. Frank, Inst,, 1877 1878 6 rues.
(7.) C~sualties'l)y overwinding. Number of occurrences, Casualties, fhtal, Casualties, not fatal, Prol)ortion fatal, 60 per cent. (8.) Casualties due to miscellaneous causes. Number of oeeurrences, Casualties, fhml, Casualties, not thtal, Propo,'ti(m fatal, 20 per cent. Total occurrences, Total thtal casualties, Total casualties not thtal, Grand total fi)r 22 months: OeelllTellces,
Total casualties~ Casualties, not t'atal, l)roportion fittal, 43 per cent.
1
2
1 1
2 1
7 1 10
8 3 6
38 14 34
49 28 31
1879 4 rues.
14 11 5
101 5.3 70
This list is not offered as a summary of accidents in tile Comstoek mines, but merely as an index to the causes which operate there t o endanger life. Many of these are common to all mining operations, hut others are quite peculiar and deserve timely discussion, fbv it is supposed that they are likely to increase in force with the deepening of the mines, whleh is now rapidly progressing. In the third class, or those e~lsualties which are due to the high t e m perature of the mines and the rock in which they are opened~ we h a v e some of the most singular occurrences known in mining. The inj u ties by scalding were occasioned entirely by falling into the hot m i n e waters. Their temperature varies with the locality, but the maximm~l which 1 have observed is 156 ° Fahr., and usually it is considerably below this. This temperature seems to be sufficient to produce serious effect~s. One miner, who slipped into the Julia water, sinldng n e a r l y to his knees, got out so quickly that the water did not have time t o enter l'._is shoes, and yet his legs were weahted so severely that the s k i n came ott: Tile same mine was flooded early in the present year w i t h water which was reported to have a temperature of 158 ° F a h r , and a miner who, in a fit of absent-mindedness, stepped into it, i m m e r s i n g
Sept., l s7~.]
C hu,'ch--z~lining Accidents.
169
hinlself to the chin, was ihtally injured. The water is hot and gaseous, :tnd the uutl)rtum/te m~m who falls ill it sinks deeply and probably flu(is it (li[fieult to regain the surfhee. But it is in the efl'ccts of work in hot air upon the human frame that the most remarkable easualtie~s are witnessed, and this cla~s,s is purposely put first among those which are to be discussed, because it :s~en~s probat)le that :t (-onsiderat)le proportion of all kinds of accidents in these mines are indirectly due to the heat. The proportion of fatal (.asualties is larger in this class than in any other, being 73 per cent., and ti'om the 1)eeuliar mental ettb(.ts of the heat it is ~)bvious flint it ~l~y be and l:)rob:lbly is the initiating caiise of many mishaps which w()uld under other eir('umstan('es 1)e ascribed to cull)able blundering, Oil the 1900 level of the. Gould and Curry mine a drift was run t,) :tile southward fronl the shaft, following the line of" the black dyke and lying quite near it. This proved to be one of those hot spots which l have 1)eibre described to the Institute as a marked peculiarity of the Co,nstocl¢ rocks. As a rule the drifts at this depfll have not been above 108 ° or 110 °, and many have been less hot, but this drift has several times been reported to show a temperature of 123 °, 126 °, and 128 ° Fahr. Thomas Brown, a miner working in this place, fainted, :and when taken to the surface and revived, was found to have completely lost his memory. He couhl not tell his name or where lie lived, ::rod had to be dressed and taken home by his friends. The paper which records the oeeurrenee says : " T h i s sudden loss of memory from overheating is quite common in the mines, but the e ~ c t soon disappears and the men are themselves again. This fact flmfishes un .explanation of how men, who are eonsidcred experienced miners, walk eft into Lttal winzes and chutes, seemingly with deliberate intention." A frequent accident in these mines is fainting in the shaft while the cage is rising to the surt~tee. The filintness is always felt immediately ut)oli reaching the cooler air a hundred or a hundred and fifty feet fix)m the surta(;e, where there is usually a side draft through some adit. This casualty is so comulou that a man who has been working in a hot drift is not allowed to go up alone. Long habitude to the heat is no safeguard against this danger, and serious accidents have occurred in this way. The iifintaess, i[ believe, is preceded by nausea, but insensibility folh)ws quite suddenly. Among the minor c'a.sualties I have included one which is ,said to have hal)pcned to Mr. Sutro. Being in tile Sutro tunnel betbre it made
170
Church--Minin 9 Accident<
[Jour. [Prank.h~t.~
connection with the Savage mine, and in an air temperature of 110 ~ Fahr., he went to tile air pipe to cool off, and staid there so long that the miners told hhn to get away from the pipe and let them have air. He did not move, and the aeeount says they tried to stir him up with the handles of their shovels, but he had lost all volition and could not budge. ]~'inally he was put on a car and taken out. These are the minor elthets of the heat. Its graver results are wei[ shown in the fbllowing eases of insanity and death : The first of these, which I introduce with some hesitation, is described by the Virginia Eye,dug Ohro~delc :is follows : " At half p:Lst nine o'clock Monday morning, March 1lib, 1878, a man died at the Caledonia mine in Gold Hill, under peculiar circumstances. Tile man hau[ been iddle for six months, and was working his first shift in that time, he having gone down this morning at seven o'clock. He was put t,.~ work as carman on the 1400 level. At the hour stated lie rushed into the station at the 1400 level and mid the station-tender that the wheels of his ear were smi~shed all to pieces. The station-tender walked back with hint to tim car, when it was fbund all right. The station-tender thereupon sltw that something was wrong with the man, and took hinx to the cooling-oil' place. There he soon began talking wildly and behaving boisterously, and giving other indications of mental aberration. It was thercfbre thought best to bring him to the surfitee. H e was firmly b~shed to the cage and hoisted up, but on reaching the surface he tkinted away and died in a few minutes." The heat on the 1400 level of the Caledonia is not very great, being about 90 ° IT'ahr., and this man's sudden decease may have been due t,> other causes. O f the other t:atal ea~sualtics, one was from cramps, which the account attributes to the heat, but which may have been the result of drinking ice water, and another was from a cold t~lken while cooling off after being partially overcome by the heat. It is to the drinking of ice water and tile comfort of a strong draft that the men resort for recovery fl'om the cxh:mstion caused by the heat, and though these methods, so contrary to the ordinary rules of hygiene, are put in use, several thousand ~dmes it (lay, and usually with impunity, these two instances are proot; that they may be dangerous. The miners eonsider the dnfft of cool air safcr than drinking copiously of ice water, but when in the mines I choose the latter method to save time, and neve~t~lt ill ett[~ets from it.
Sept., 1 8 7 9 . ]
Church--Mini~g Accidents.
17
The next case illustrates the violent effects which excessive heat may have upoll a person not accustomed to it : "On Friday, October 11th r 1878, John McCauley went to work for the first time in the ImperiM mine. H e was cautioned against over-exerting himself in the extreme heat of' the lower levels. He replied that he thought he was strong enough to stand anything and paid no attention to the advice. At half-past two in the afternoon he was brought to the surface in ar~ unconscious state, and died the next morning at half-pa~t ten o'clock." Two other cases very similar to this have (~ccurrod in the I m p e r i a l within a few years. This mine is excavated in one of the hot spots o f the Comstock. The hot drift on the 1900 level of' the Gould and Curry is the scene of the most serious of these casualties due to heat. Five men were sent there, in June, 1878, to load a donkey pump on a car. The work was so exhausting that when the pump caught on a plank they were not able to move it. They seem to have been in a state of mental confusion, but felt that they could not remain longer. Starting up a winze which connects with the 1700 level one man fell on the way, and the others were ark'aid to stop to help him, but pressed on, reaching the 1700 in half an hour from the time they left it. They wer e,very confllsed and nearly speechless, and hardly realized what had occurred. Three meu went down to the rescue and found the fallen man still alive. Clearing the pumt, they got into the car and signalled to hoist, but on the way up the wiuze the man they had gone to rescue reeled and fell oft: The car was stopped at once, but he was jammed betweelt, it and the brattice so first that the others left him and went for help:. They all gave out, two half way up, and the other just as he reached the 1700 level, where a friendly hand pulled him up. A new rescue party went down and found two men dead, and the third died SOOll after. The shift boss reports that "the accident was due solely to theheat, as the air is good enough and pure enough, barring the heat." The winze was not an abandoned one, but in daily use. A heavy volume of steam is reported to rise through it from tim 1900 level, the teml?erature of which, at the time of this accident, is given at 128 ° Fahr. [ gather from the detailed account that the death of the men is possibly attributable to the thct that when the miner tell off the c~tr the latter was stopped in a place that was hotter than the rest of the WillZe. It is to be regretted that no adequate stt~(lies have been made upol~
7172
G'hut'ch--Jfininy Aeeident.~.
[Jom,. Frank I,st.,
the prceisc physiolovMd phcnomcna presented b v death under these circumstances. The h~val requirements are satisfied when it is proved ~that the ~asualtv was due to " ]mat," but if' the theory of heat lwodu,:. tion in these rocks, which I have advoc'ated before you, is correet, "lnd currents of hot Kas, rich in carbonic acid, are pouring through narrow belts of shattered rock, the death of men who are stopped in one of thesc belts may have a more complex cause. (4.) The most appalling accident which can occur in mining work, the fidling of men down a deep shaft, repeats itself in the Comsto& mines with a fi'equency which, I believe, is unknown elsewhere. Sixteen occurrences of this kind took phtee in twenty-two months, and ten of the ea,*ualties were thtal. There we.re seven ildls in the shaft, six in winzes and one in a chute, and three in the flom:s. One of these deaths was traceable to the ettb,ets of ibul air~ the lights having gone .out and the party being on the cage in retreat from the drift. These drcadihl accidents being more conlmon on the Comstoek than ~in any other mines that I know of; it is important to ascertain whether this frequency is attributable to the heat. In some eases we may answer in the affirmative. When a timberman repairing the upca.st :shaft of an unusually hot mine fitlls to the bottom we may fairly con*elude that tile tendency of blood to the head which the lifting of a heavy weight oceasions may have been increased to momentary stupefaction by the heat, steam and gases of tile shaft. But though my own impression befbrc examining this subject was that the heat was largely accountable tbr these mishaps, I am forced, by a study of the e'lsualtics in this record, to admit that this is not the most frequent cause of them. I f the Comstock miner is more liable than his tbllows to this tbrm of accident, it is because he is more oi~en called to work in the shatt~ after they have been completed. The Comstock shafts are all sunk in the hanging wall, and the vast excavations which have been made in most of the mines make the settling of this wall inevitable. But besides that, the Comstoek rocks are forever moving, swelling and forcing the shafgs out of line. No shaft there is in pcribctly good condition. Some stand remarkably well, and kee t) in working order tbr years, while ()tilers require fi-equem repairs; but from the day they are completed their deterioration is steady, until a general overhauling is necessary. They are timbered in a maturer which allows remarkable variation fi~om their original alignment without loss of local support to the ground, and this timber-
Sept', lS79.]
C h ttreh--Jiining A ecklents.
17.1t;
ing is rapidly and eonveniemly readjusted when pushed too far out of" lira,. The work of relmir is necessarily dangerous and more hazard,,us in 't hot steaming upcast, shaft than in a cool one, and it is to the t?equeney with whMl the Comstoek miner is c,"filM Ul)ml to perform ~]~is work that the number of thlls in the shaft is to be attributed. I t is also undeniable that the unNvorable heat conditions may contribute ~ssentially to the result, but of the two cattses I co~lsider that frequent .ppo,'tunity is the greater. But the falling of timber,hen is not the only nmde in which this. a,.ddent occurs. Another is the pr(xtuet of pure fbrgeffuluess. 2k mar~ working near the shaft will sometimes step off upon ~acaney and mee~ his death. The movement is made quietly--not in the heat of action, hut after the completion of some t~sk~and above groua~d such actions~ are attributed to " al)sent-inindedness." I think thks state of inactive t,er(.eption is exceptionally fl-equent among Comstoek. miners, and it ~tan(ls in such strong contrast to the lmbits of forethottghtfulness to which they train themselves that we mu,t atta'ibute it to the eflhct of" physiml exertion in hot air. Another class of thlls in the shaft are partly due to the high professional spirit and sense of individual rest~rrsibility , which makes f]ae Western Ininer one of the most trustworthy of his class. This mode of occurrence, which is unexpectedly freetuent, is the pushing o f a calinto a shaft where there is no cage. This i~ sometimes due to pm~e absent-mindc~tness, and sometimes to an interrtrption of file rou~ime work by a cage going up empty, with a message, with tools or with p~ssenger. It is said to be a fact that when a carmaal has pushed hi~ ear to the ()pen shaft and has sttddenly awakened to the drcadflfl s i t ~ ation, he never fails to .sacrifice his own life in eflbrt% however lmI),2 lesb to stop it. Whenever a ear thtmders down the shat~, there is always a man with it, and whenever the circumstances have come ua~der observation, it has been evident that the loss of life was not due to, stupefaction but to a dogged determination to stake everything on the hol)e of preventing a possible calamity to men below. The spirit is well illustrated by the act of a man who fell down a shaft at Bodie, and used his 1-tst breath in calling out " L o o k out below t" Though this easualty appears so frightful to those who witness it, it is probably as painless as other modes of eertaio instantaneous death. I have been told that the unforttmate men always lose their shoes i~t their fall~ an4
174
Church--Mining Acciden~,.
[Jour. Frank. lnst,
also that the)' invariably reach the bottom sooner than the ear, if o~e talls with the man. (5.) The history of bluest accidents ill the Comstock mine.s ent~Jrccs the truth that the nitroglycerine explosives do not enjoy the imruuuitv fl'om ignition by friction which has been asserted fbr them so confi.dently. We have to admit that a box of cartridges can be thrown off' a house with salbty, tbr that has frequently been done, but im'los(.~l in a drill-hole they have been fired repeatedly by friction, jarring or a blow. ()tit of tburteen accidents five occurred front the exph)sion of nnsuspeetcd cartridges by one of these causes. Two cases of wounding are peculiar trom the fact that the exph~ding cartridges had been in the rock a long time. Each of them lay, not in the header, but in the floor of a dritk or chamber, and the accident occurred when orders were given to level up the floor. The exph)sions were in diffhrent mines, and one ()t" tim miners was using a pick, the other a gad. ~Neither was killed. Two men were wounded by the explosion of a cartridge which they were drilling out for repriming. Three accidents oecm'red from the explosion of ohl cartridges left in the header, the presence of which was not suspected, and which were fired, not by direct impact of the tool, but by the jar or the crowding in of the rock upon the cartridge owing to the starting of a new drill-hole near by. Two of these were <.aused by machine drills, and one by hand drilling. I t is supposed that in some cases at least the exploding cartridge was not a complete one but merely a fragment, the upper portion having done its work. This seems probable, for instance, in the cases of fl~e two men who were injured while levelling off the floor, for it is hardly conceivable that a full cartridge could blow up the floor beneath a man's feet and leave him alive. One of the explosions took place under peculiar circumstances, which exhibit very well the sensensitiveness o f nitroglycerine to the condition,~ in which it is placed. A hole having missed fire, the next shift opened and recharged it. After lighting the fhse the men waited the usual time, and one of them then went to the face and found the cartridge was "boiling," making what miners call a "stinker." It was concluded to (lrown the hole out, and a man took up water from the wet floor in his :shovel and threw it on the [)oiling cartridge. While stooping for another shovelful, the half-burnt charge exploded. The superintend-
~ept,, 1879.]
Church--Mining Accidents.
175
~,nt, Mr. Forman, who w ~ t)resent, attributes the explosion to the confinement of gas by the water, and the suggestion is a sensible one. (6.) Hoisting oil the Comstock has peculiar dangers from the movement of ground in the shafts already spoken of. It is often imlmssible ~o ke~l) the guides in anything approaching a straight line. The shove is n.t only eonsideral)le, but it is frequently (~nfined to short reaches in the shaft, and this disl)laeement of line is the cause of frequent dang(,rs an
176
Ch~t~'eh--~Iini~.,q Aecide)#s.
[aonr. KranI~.Inst.
The gallmvs franies at most of tile old shafts are thirtv-five feet high, and with a "doul~le-devker " cage that takes up twelve or ~.mrteen i~et of this space, it is evident the engineer has but a small margin fin: safiey. 'l'he new shafts have ti~unes fbrty-five feet high. [t seems to me that the dislndinqtion t~, use preventive appliances should be overcome. '12he tendency on tlm Comstoek is to employ unhalaneed reels~ and with these, mere bleeding of the steam pipe should be sufficient to preveut serious injury. With balanced reels it would be absolutely necessary to put on the bntke also. (8.) One of the aeeidents classed among the miseellaneons causes is worthy of attention. 8everal years ago an eleetrie signaling apparatus was inm£tueed into the Savage mine, but abandoned on account of the uncertainty of its signals, which would sometimes sound without human aid. In 1877 a new apparatus wax put in with improvements, which it was thought wouhl prevent this disadvantage, but after working well fbr some time, it thiled one morning and caused a fatal e~'tsualV by sounding only three bells, when ten were intended. Whether the signal man was at fault ix doubtful, but it is a fact that the apparatus had worked I)adly that morning, and before the aecident a man had been stationed to signal with the bell-rope in case the battery did not work. There is little confidence in the electric mode of signaling, and, I believe, it is not in use now in any mine on the lode. A small wire hand-rope is used, and on the whole is safe and eonvenient. In looldng over this list of casualties it is evident that the accidents which possess most interest are those whieh have near or remote connection with the heat of the mines, ti-)r the latter are sinking with great rapidity, and becoming hotter each year. During the past eighteen months they have been deepened tbur hundred to six hundred ti~et, and it is diffieult to deny that the greater depth increases the chances of accident in minos which, in addition to the ordinary liabilities of nfining work, have the insidious and ever present etti~ets of hot air~ water and reek upon the l)hysical and mental condition of the men. While I have never myself doubted the ability of the exedlent managers to carry the works in these hot reeks down to the greatest depths that ~re antieipated fl)r mining in any region, I find there is widespread doubt in the West upon this subject. There is an impression that the Comstoek lode has nearly reached the end of the mining rope, and the reason usually given is that life cannot be sustained in the great heat of the lowest workings, which heat the popular mind loves
Sept, i 8 7 9 . ]
CA~ereh--l~Ti~ing Accident.s.
177
to exaggerate. The record 1 present in this paper should be sufficient to dispel such doubts. Out of 101 accidents twelve were directly caused by the heat or hot water. Undoubtedly the falls of men down a sha{~ have been caused sometimes by sudden exhaustion, due to the heat and steam h~ upcast shafts, but on looking over the accounts of the accidents of this kind, which are included in the above list, I cannot find any of them that show a connection with this cause. The casualties positively traceable to the heat are, therefore, twelve per vent. of the whole. Prol)al)ly the heat increa~ses the bad effects of powder fumes and natural gases, and by making repairs to the shafts more frequently necessary it adds indirectly to the occasions when disasters may occur. I also eontbss to the belief, which is not sustained by obserw~tions upon specific casualties, that some alh)wance should be made for a less active mental condition, a dulling of the faculties, and ,~ vertain recklessness to which the heat sometimes goads the men. On the other hand the heat makes them more cautious except when under momentary impulses, and I have never seen American miners more eareihl of the,nselves than in these mines. On the whole, the good and bad effects of the heat seem to nearly balance each other, and I think that an allowance of five per cent. for the casualties indirectly caused by the high heat would be sufficient. The specific cases which I present do not warrant even that allowance. The accidents recorded here relate to a time when the number of nfiners at work in the district was from three thousand to thirty-five hundred, including top men and underground men. Most of them worked eight hours, but some of" those on top had twelve hour shifts, and probably there was a constant force of nine hundred or one thousand men below. It is not possible to make a comparison between these casualties an~ the, anmunt of ore ralsed, as the practice is in statistics of coal mines,. fbr the reason that only two out of about forty mines were producing: much ore throughout the period covered by the list. The comparison can be made for those tw% the Consolidated Virginia and California, and is as follows for the year 1878 : Proportion to tons ore.
Number of accidents, Fatal casualties, Casualties not fatal, Tons of ore extracted,
10, 5, 8, 257,718.
1 to 25,771 1 to 51,542 1 to 32,214
Of the casualties included in the list for twenty-two months there WHOLE No. VoL. CVIII.--(THIRI) SERIf, Vol. lxxviii.)
13
178
Cht~rch
MiMrt9 Ae,'.ident.~.
[aour. Frank. Inst~
were ill these two mines twenty-five 'w.eidents, twelve fatal, and eighteen not iMal easualtics, or twenty-five, twenty-two aml a halt', and twenty-six I}el• vent. of the whole. Frmn all these fiu,ts I conclude that iuereasing heat will not debar :the Comst()(d< mines fl:Om continuing to tho gr(,at(~st depths xvhieh are .L.mlsitlered practicable in the existing m!iustn/ent ()i' mining apldianees to the market vahm oF mining products. It is true that an air temperatm'e of" 1t)8 ° Fahr. is c'omm, m at the 2000 feot level, while 11(1° and 112 <~'are not infrequently ol)serw~d, and that a drift wl,idl showed a ~emperatm'e of 123 °, 126 ° and 128 ° Fahr., 'recording to dift~rent relmrt.~, ]~Ls proved to be tim most deadly on the lode. i t is also true that the temperature of the ro~'k is invreasing, and with it tlmt ,~f the air, and at stone dept] b tbr the calculation of whi('h tlmr(, are abs0iutelv no data, tim tempe.rature of this drift may be expected to prevail throughout the lode unless the present conditions change. But flfi~ being an air temperature, it is always 1)ossible to mitigate it by artificial means. I t is already observable that drifts 1800 feet below the surface may show a much higher heat than others -100 fi~et below them. lligh temperature is largely a matter of locality and tempora W emulitions, and by vari,us expedients it may be confined to its l~alities~ or combated in other ways. Deep mining, by extending the line of work through the moving hanging wall, and compelling increased repairs to shafts, will perhaps ~ M to heighten the already great fl'equeney of fidls of men. In ~ddition to the heat , the peculiar mode of timbering in s(tuare :sets, the almost exclusive use of nitroglyeerine powders, the neeessity o f tYequent repairs to shaft timbers, the incessant movement of the rocks through which the shafts are sunk, making accidents in hoisting more than ordinarily frequent, and the necessity of transporting large •laantities of rock through narrow gangways entirely by human labor, :are the conditions in which mining on the Comstoek may l)e said to suffer rather more than the usual liability to danger. Two of these eauseg both eonneeted with the movement of the groined, may be expected to h~er~se with depth. Together with lain heat they comprise forty per e,,~zat, of the whole number of a('eidents, and we may therefore sum up ,,)~r conclusions by saying that the. conditions of deep mining will iinerea~e tbr~y per cent. of the causes which lead to casualties, and will ' ite~ve sixty per cent. unaffected. What the amount of this increase will he emmot be ibretold, and indeed cannot be estimated until an ore body
Sept., 1879.]
1'he Cbmpa.~s.
179
has been fi~und and worked at great depth. So far tile year 1879, whi(:h is pre-eminently one of deep sinking oil the Comstock, has been remarkably free fi'om casualties. The administration of the mines is excellent, and the oversight ample. Though there is no declared law, I observed that an accident wa~slikely to be tbllowed by the discharge of some miners, and several times the ,suitbrcrs went 1)ef'(}re a magistrate and made oath that they were not only entirely innocent of negligence, but absolutely ignorant that there was any danger impending, or that there was any one near who could be injured if an accident should take place. The managers seem to have crone to the conclusion, which guides the framers of some Euro}~ean mining laws, that accidents will not cease until the damage is assessed on every one in the neighborhood of the casualty, innocent or guilty. The 5[iners' Union is an active and powerful body, and does not hesitate to express an Olfinion on the conduct of the mines.
The C o m p a s s . - - T h e secret of the steadiness of a large compass is the longness of its vibrational period, and a small card would have the same steadiness as a large one if its vibrational period were the same. How little this is known is illustrated by the methods of procuring steadiness in common use. In some (as in the Admiralty !' J " card, provided for use in stormy weather) there is a swelling in the middle of' each of the steel needles to make them heavier; in others heavy t)ra~ss weight~s are attaehed to the compass cards as near the centre as may be, being sometimes, for instance, in the 'form of a small bra~ ring of about an inch and a half in diameter. Another method, scarcely less scientific, is to blunt the bearing-point by grinding it or striking it with a hammer, as has not unfrequently been done to render tile compass " less lively," or to fill the cup with brick-dust, as is reported by the Liverpool Compass Committee to have been once done at sea by a captain who w~s surprised to find afterwards that his compa~ could not be misted within a couple of points. All, these methods are founded on the idea that friction on the bearing-point is the cure for unsteadiness. In reali W fl,ietion introduces a peculiar unsteadiness of a very serious kind, and is very ineffective in remedying the propeL" unsteadiness of which something is essential and inevitable in a corn pass on board a ship rolling in a heavy sea and steering on any other course than due east or due west.~Sir IV. Thompson.
Church~Mi~nln9 Accidents.
[Jour. Frank. Ir~e~
ACCIDENTS IN T I I E C()MSTOCK M I N E S A N D T H E I I ~ R E L A T I O N TO DEE1 ) M I N I N G . e
113), JotlN A. CIrURCH, M.E. A paper read at the Pittsburgh meeting of the American Institute of ~Iining Engineers, May, 1879. Early in the month of August, 1877, a miner in Gold Hill, Neva~lh, " rome the unlucky remark that, according to his observation, that month was usnally quite 5-ee fi'om accidents in the mines. Never" was pre~ge wider from the truth. When the mouth closed twelve mishaps had occurred, killing six and wounding nine persons, and for" the rest of that year the Comstock mitring communities were kept in a ferment by the frequent occurrence of appalling di~sters. There w,'~s a real tidal wave of calamity sweeping over the mines, which has not been repeated since, and according to common report was never known before on the Comstoek. I was much interested in studying the character of these misfi)rtunes, which also aroused concerted action on thepart of the miners, and I have collected a list of the accidents which. took place from July, 1877, to May, 1879. The number in this period of twenty-two months is 101, killing immediately 53 persons and. wounding 70 others. This list is incomplete in every way. All accidents which did not injure persons are omitted, and there are several which were of a threatening kind but ibrtunately (lid no damage to hmnan beings. Probably others have been overlooked which dh[ belong to the category included in my lists. Finally, no efibrt h~s been made to ascertain how many of the wounded died of their wounds, and the nmuber of t:atal casualties include~s only those who died so soon after their injury that their death became a part of the current records of the accident. Many of these accidents belong to the usual classes of mishaps it~ nfines and will receive no extended discussion. Others arc worth examination from their connection with labor in hot mines, deep raining, and other causes intimately dependent on the local conditions off the Comstock. They may all be cl.~ssified under eight general heads : 1. Falls of rock, timber, etc. 2. Tramming. 3. Efthcts of heat. 4. Falls of men. 5. Explosions. 6. tIoisting apparatu,s, 7, O v e r -
Sept,, 1879.]
!67
Ct, trch--Mi'ai~N Accidents.
winding. 8. Miscellaneous. The distribution among these groups in each )'car is shown in the ibllowing summary : .m
1877 1878 6 mos.
(1.) Casualties due to fidls of rock, ice, timber, etc. Number of (x'x~'urrences, Casualties, thtal, Casualties, not fatal, Proportion thtal, 36 per cent. (2.) Casualties in tramming. Nmnber of occurrences, . Casualties, taml, Casualties, not |htal, Proportion ~atal, 12~ per cent. (3.) Casualti(~ due to heat.
1879 4 mos.
8 2
7 4
8 3
7
4
5
4 1
3 0
-t
3
1 1
2 1 1
1 1
8 7 3
7 2 5
7 6 1
2 2
5
6
3
3 5
2 6
5
2 2
3 6
1
,~'calding :
Number of occurrences, Casualties, thtal, C~t~ualties, not thtal, Proportion fatal, 33 per cent. O~erheating :
Number of occurrences, CCsualties, fatal, Casualties, not thtal, Proportion thtal, 73 per cent. (4.) Casualties due to Nlls of men. Number of occurrences, Casualties, fatal, Casualties, not fhtal, Proportion fatal, 62~- per cent. (5.) Casualties due to explosions. Number of occurrences, Casualties, fittal, C~sualtles, not thml, Proportion fitta|, 71 per cent. (6.) Casualties in hoisting. Number of occurrences, Casualties, Ntal, Ca~sualties, not ti~tal, Proportion fatal, 43 per cent.
C hu.rch~Kini~g A eeide~ds.
168
[Jour. Frank, Inst,, 1877 1878 6 rues.
(7.) C~sualties'l)y overwinding. Number of occurrences, Casualties, fhtal, Casualties, not fatal, Prol)ortion fatal, 60 per cent. (8.) Casualties due to miscellaneous causes. Number of oeeurrences, Casualties, fhml, Casualties, not thtal, Propo,'ti(m fatal, 20 per cent. Total occurrences, Total thtal casualties, Total casualties not thtal, Grand total fi)r 22 months: OeelllTellces,
Total casualties~ Casualties, not t'atal, l)roportion fittal, 43 per cent.
1
2
1 1
2 1
7 1 10
8 3 6
38 14 34
49 28 31
1879 4 rues.
14 11 5
101 5.3 70
This list is not offered as a summary of accidents in tile Comstoek mines, but merely as an index to the causes which operate there t o endanger life. Many of these are common to all mining operations, hut others are quite peculiar and deserve timely discussion, fbv it is supposed that they are likely to increase in force with the deepening of the mines, whleh is now rapidly progressing. In the third class, or those e~lsualties which are due to the high t e m perature of the mines and the rock in which they are opened~ we h a v e some of the most singular occurrences known in mining. The inj u ties by scalding were occasioned entirely by falling into the hot m i n e waters. Their temperature varies with the locality, but the maximm~l which 1 have observed is 156 ° Fahr., and usually it is considerably below this. This temperature seems to be sufficient to produce serious effect~s. One miner, who slipped into the Julia water, sinldng n e a r l y to his knees, got out so quickly that the water did not have time t o enter l'._is shoes, and yet his legs were weahted so severely that the s k i n came ott: Tile same mine was flooded early in the present year w i t h water which was reported to have a temperature of 158 ° F a h r , and a miner who, in a fit of absent-mindedness, stepped into it, i m m e r s i n g
Sept., l s7~.]
C hu,'ch--z~lining Accidents.
169
hinlself to the chin, was ihtally injured. The water is hot and gaseous, :tnd the uutl)rtum/te m~m who falls ill it sinks deeply and probably flu(is it (li[fieult to regain the surfhee. But it is in the efl'ccts of work in hot air upon the human frame that the most remarkable easualtie~s are witnessed, and this cla~s,s is purposely put first among those which are to be discussed, because it :s~en~s probat)le that :t (-onsiderat)le proportion of all kinds of accidents in these mines are indirectly due to the heat. The proportion of fatal (.asualties is larger in this class than in any other, being 73 per cent., and ti'om the 1)eeuliar mental ettb(.ts of the heat it is ~)bvious flint it ~l~y be and l:)rob:lbly is the initiating caiise of many mishaps which w()uld under other eir('umstan('es 1)e ascribed to cull)able blundering, Oil the 1900 level of the. Gould and Curry mine a drift was run t,) :tile southward fronl the shaft, following the line of" the black dyke and lying quite near it. This proved to be one of those hot spots which l have 1)eibre described to the Institute as a marked peculiarity of the Co,nstocl¢ rocks. As a rule the drifts at this depfll have not been above 108 ° or 110 °, and many have been less hot, but this drift has several times been reported to show a temperature of 123 °, 126 °, and 128 ° Fahr. Thomas Brown, a miner working in this place, fainted, :and when taken to the surface and revived, was found to have completely lost his memory. He couhl not tell his name or where lie lived, ::rod had to be dressed and taken home by his friends. The paper which records the oeeurrenee says : " T h i s sudden loss of memory from overheating is quite common in the mines, but the e ~ c t soon disappears and the men are themselves again. This fact flmfishes un .explanation of how men, who are eonsidcred experienced miners, walk eft into Lttal winzes and chutes, seemingly with deliberate intention." A frequent accident in these mines is fainting in the shaft while the cage is rising to the surt~tee. The filintness is always felt immediately ut)oli reaching the cooler air a hundred or a hundred and fifty feet fix)m the surta(;e, where there is usually a side draft through some adit. This casualty is so comulou that a man who has been working in a hot drift is not allowed to go up alone. Long habitude to the heat is no safeguard against this danger, and serious accidents have occurred in this way. The iifintaess, i[ believe, is preceded by nausea, but insensibility folh)ws quite suddenly. Among the minor c'a.sualties I have included one which is ,said to have hal)pcned to Mr. Sutro. Being in tile Sutro tunnel betbre it made
170
Church--Minin 9 Accident<
[Jour. [Prank.h~t.~
connection with the Savage mine, and in an air temperature of 110 ~ Fahr., he went to tile air pipe to cool off, and staid there so long that the miners told hhn to get away from the pipe and let them have air. He did not move, and the aeeount says they tried to stir him up with the handles of their shovels, but he had lost all volition and could not budge. ]~'inally he was put on a car and taken out. These are the minor elthets of the heat. Its graver results are wei[ shown in the fbllowing eases of insanity and death : The first of these, which I introduce with some hesitation, is described by the Virginia Eye,dug Ohro~delc :is follows : " At half p:Lst nine o'clock Monday morning, March 1lib, 1878, a man died at the Caledonia mine in Gold Hill, under peculiar circumstances. Tile man hau[ been iddle for six months, and was working his first shift in that time, he having gone down this morning at seven o'clock. He was put t,.~ work as carman on the 1400 level. At the hour stated lie rushed into the station at the 1400 level and mid the station-tender that the wheels of his ear were smi~shed all to pieces. The station-tender walked back with hint to tim car, when it was fbund all right. The station-tender thereupon sltw that something was wrong with the man, and took hinx to the cooling-oil' place. There he soon began talking wildly and behaving boisterously, and giving other indications of mental aberration. It was thercfbre thought best to bring him to the surfitee. H e was firmly b~shed to the cage and hoisted up, but on reaching the surface he tkinted away and died in a few minutes." The heat on the 1400 level of the Caledonia is not very great, being about 90 ° IT'ahr., and this man's sudden decease may have been due t,> other causes. O f the other t:atal ea~sualtics, one was from cramps, which the account attributes to the heat, but which may have been the result of drinking ice water, and another was from a cold t~lken while cooling off after being partially overcome by the heat. It is to the drinking of ice water and tile comfort of a strong draft that the men resort for recovery fl'om the cxh:mstion caused by the heat, and though these methods, so contrary to the ordinary rules of hygiene, are put in use, several thousand ~dmes it (lay, and usually with impunity, these two instances are proot; that they may be dangerous. The miners eonsider the dnfft of cool air safcr than drinking copiously of ice water, but when in the mines I choose the latter method to save time, and neve~t~lt ill ett[~ets from it.
Sept., 1 8 7 9 . ]
Church--Mini~g Accidents.
17
The next case illustrates the violent effects which excessive heat may have upoll a person not accustomed to it : "On Friday, October 11th r 1878, John McCauley went to work for the first time in the ImperiM mine. H e was cautioned against over-exerting himself in the extreme heat of' the lower levels. He replied that he thought he was strong enough to stand anything and paid no attention to the advice. At half-past two in the afternoon he was brought to the surface in ar~ unconscious state, and died the next morning at half-pa~t ten o'clock." Two other cases very similar to this have (~ccurrod in the I m p e r i a l within a few years. This mine is excavated in one of the hot spots o f the Comstock. The hot drift on the 1900 level of' the Gould and Curry is the scene of the most serious of these casualties due to heat. Five men were sent there, in June, 1878, to load a donkey pump on a car. The work was so exhausting that when the pump caught on a plank they were not able to move it. They seem to have been in a state of mental confusion, but felt that they could not remain longer. Starting up a winze which connects with the 1700 level one man fell on the way, and the others were ark'aid to stop to help him, but pressed on, reaching the 1700 in half an hour from the time they left it. They wer e,very confllsed and nearly speechless, and hardly realized what had occurred. Three meu went down to the rescue and found the fallen man still alive. Clearing the pumt, they got into the car and signalled to hoist, but on the way up the wiuze the man they had gone to rescue reeled and fell oft: The car was stopped at once, but he was jammed betweelt, it and the brattice so first that the others left him and went for help:. They all gave out, two half way up, and the other just as he reached the 1700 level, where a friendly hand pulled him up. A new rescue party went down and found two men dead, and the third died SOOll after. The shift boss reports that "the accident was due solely to theheat, as the air is good enough and pure enough, barring the heat." The winze was not an abandoned one, but in daily use. A heavy volume of steam is reported to rise through it from tim 1900 level, the teml?erature of which, at the time of this accident, is given at 128 ° Fahr. [ gather from the detailed account that the death of the men is possibly attributable to the thct that when the miner tell off the c~tr the latter was stopped in a place that was hotter than the rest of the WillZe. It is to be regretted that no adequate stt~(lies have been made upol~
7172
G'hut'ch--Jfininy Aeeident.~.
[Jom,. Frank I,st.,
the prceisc physiolovMd phcnomcna presented b v death under these circumstances. The h~val requirements are satisfied when it is proved ~that the ~asualtv was due to " ]mat," but if' the theory of heat lwodu,:. tion in these rocks, which I have advoc'ated before you, is correet, "lnd currents of hot Kas, rich in carbonic acid, are pouring through narrow belts of shattered rock, the death of men who are stopped in one of thesc belts may have a more complex cause. (4.) The most appalling accident which can occur in mining work, the fidling of men down a deep shaft, repeats itself in the Comsto& mines with a fi'equency which, I believe, is unknown elsewhere. Sixteen occurrences of this kind took phtee in twenty-two months, and ten of the ea,*ualties were thtal. There we.re seven ildls in the shaft, six in winzes and one in a chute, and three in the flom:s. One of these deaths was traceable to the ettb,ets of ibul air~ the lights having gone .out and the party being on the cage in retreat from the drift. These drcadihl accidents being more conlmon on the Comstoek than ~in any other mines that I know of; it is important to ascertain whether this frequency is attributable to the heat. In some eases we may answer in the affirmative. When a timberman repairing the upca.st :shaft of an unusually hot mine fitlls to the bottom we may fairly con*elude that tile tendency of blood to the head which the lifting of a heavy weight oceasions may have been increased to momentary stupefaction by the heat, steam and gases of tile shaft. But though my own impression befbrc examining this subject was that the heat was largely accountable tbr these mishaps, I am forced, by a study of the e'lsualtics in this record, to admit that this is not the most frequent cause of them. I f the Comstock miner is more liable than his tbllows to this tbrm of accident, it is because he is more oi~en called to work in the shatt~ after they have been completed. The Comstock shafts are all sunk in the hanging wall, and the vast excavations which have been made in most of the mines make the settling of this wall inevitable. But besides that, the Comstoek rocks are forever moving, swelling and forcing the shafgs out of line. No shaft there is in pcribctly good condition. Some stand remarkably well, and kee t) in working order tbr years, while ()tilers require fi-equem repairs; but from the day they are completed their deterioration is steady, until a general overhauling is necessary. They are timbered in a maturer which allows remarkable variation fi~om their original alignment without loss of local support to the ground, and this timber-
Sept', lS79.]
C h ttreh--Jiining A ecklents.
17.1t;
ing is rapidly and eonveniemly readjusted when pushed too far out of" lira,. The work of relmir is necessarily dangerous and more hazard,,us in 't hot steaming upcast, shaft than in a cool one, and it is to the t?equeney with whMl the Comstoek miner is c,"filM Ul)ml to perform ~]~is work that the number of thlls in the shaft is to be attributed. I t is also undeniable that the unNvorable heat conditions may contribute ~ssentially to the result, but of the two cattses I co~lsider that frequent .ppo,'tunity is the greater. But the falling of timber,hen is not the only nmde in which this. a,.ddent occurs. Another is the pr(xtuet of pure fbrgeffuluess. 2k mar~ working near the shaft will sometimes step off upon ~acaney and mee~ his death. The movement is made quietly--not in the heat of action, hut after the completion of some t~sk~and above groua~d such actions~ are attributed to " al)sent-inindedness." I think thks state of inactive t,er(.eption is exceptionally fl-equent among Comstoek. miners, and it ~tan(ls in such strong contrast to the lmbits of forethottghtfulness to which they train themselves that we mu,t atta'ibute it to the eflhct of" physiml exertion in hot air. Another class of thlls in the shaft are partly due to the high professional spirit and sense of individual rest~rrsibility , which makes f]ae Western Ininer one of the most trustworthy of his class. This mode of occurrence, which is unexpectedly freetuent, is the pushing o f a calinto a shaft where there is no cage. This i~ sometimes due to pm~e absent-mindc~tness, and sometimes to an interrtrption of file rou~ime work by a cage going up empty, with a message, with tools or with p~ssenger. It is said to be a fact that when a carmaal has pushed hi~ ear to the ()pen shaft and has sttddenly awakened to the drcadflfl s i t ~ ation, he never fails to .sacrifice his own life in eflbrt% however lmI),2 lesb to stop it. Whenever a ear thtmders down the shat~, there is always a man with it, and whenever the circumstances have come ua~der observation, it has been evident that the loss of life was not due to, stupefaction but to a dogged determination to stake everything on the hol)e of preventing a possible calamity to men below. The spirit is well illustrated by the act of a man who fell down a shaft at Bodie, and used his 1-tst breath in calling out " L o o k out below t" Though this easualty appears so frightful to those who witness it, it is probably as painless as other modes of eertaio instantaneous death. I have been told that the unforttmate men always lose their shoes i~t their fall~ an4
174
Church--Mining Acciden~,.
[Jour. Frank. lnst,
also that the)' invariably reach the bottom sooner than the ear, if o~e talls with the man. (5.) The history of bluest accidents ill the Comstock mine.s ent~Jrccs the truth that the nitroglycerine explosives do not enjoy the imruuuitv fl'om ignition by friction which has been asserted fbr them so confi.dently. We have to admit that a box of cartridges can be thrown off' a house with salbty, tbr that has frequently been done, but im'los(.~l in a drill-hole they have been fired repeatedly by friction, jarring or a blow. ()tit of tburteen accidents five occurred front the exph)sion of nnsuspeetcd cartridges by one of these causes. Two cases of wounding are peculiar trom the fact that the exph~ding cartridges had been in the rock a long time. Each of them lay, not in the header, but in the floor of a dritk or chamber, and the accident occurred when orders were given to level up the floor. The exph)sions were in diffhrent mines, and one ()t" tim miners was using a pick, the other a gad. ~Neither was killed. Two men were wounded by the explosion of a cartridge which they were drilling out for repriming. Three accidents oecm'red from the explosion of ohl cartridges left in the header, the presence of which was not suspected, and which were fired, not by direct impact of the tool, but by the jar or the crowding in of the rock upon the cartridge owing to the starting of a new drill-hole near by. Two of these were <.aused by machine drills, and one by hand drilling. I t is supposed that in some cases at least the exploding cartridge was not a complete one but merely a fragment, the upper portion having done its work. This seems probable, for instance, in the cases of fl~e two men who were injured while levelling off the floor, for it is hardly conceivable that a full cartridge could blow up the floor beneath a man's feet and leave him alive. One of the explosions took place under peculiar circumstances, which exhibit very well the sensensitiveness o f nitroglycerine to the condition,~ in which it is placed. A hole having missed fire, the next shift opened and recharged it. After lighting the fhse the men waited the usual time, and one of them then went to the face and found the cartridge was "boiling," making what miners call a "stinker." It was concluded to (lrown the hole out, and a man took up water from the wet floor in his :shovel and threw it on the [)oiling cartridge. While stooping for another shovelful, the half-burnt charge exploded. The superintend-
~ept,, 1879.]
Church--Mining Accidents.
175
~,nt, Mr. Forman, who w ~ t)resent, attributes the explosion to the confinement of gas by the water, and the suggestion is a sensible one. (6.) Hoisting oil the Comstock has peculiar dangers from the movement of ground in the shafts already spoken of. It is often imlmssible ~o ke~l) the guides in anything approaching a straight line. The shove is n.t only eonsideral)le, but it is frequently (~nfined to short reaches in the shaft, and this disl)laeement of line is the cause of frequent dang(,rs an
176
Ch~t~'eh--~Iini~.,q Aecide)#s.
[aonr. KranI~.Inst.
The gallmvs franies at most of tile old shafts are thirtv-five feet high, and with a "doul~le-devker " cage that takes up twelve or ~.mrteen i~et of this space, it is evident the engineer has but a small margin fin: safiey. 'l'he new shafts have ti~unes fbrty-five feet high. [t seems to me that the dislndinqtion t~, use preventive appliances should be overcome. '12he tendency on tlm Comstoek is to employ unhalaneed reels~ and with these, mere bleeding of the steam pipe should be sufficient to preveut serious injury. With balanced reels it would be absolutely necessary to put on the bntke also. (8.) One of the aeeidents classed among the miseellaneons causes is worthy of attention. 8everal years ago an eleetrie signaling apparatus was inm£tueed into the Savage mine, but abandoned on account of the uncertainty of its signals, which would sometimes sound without human aid. In 1877 a new apparatus wax put in with improvements, which it was thought wouhl prevent this disadvantage, but after working well fbr some time, it thiled one morning and caused a fatal e~'tsualV by sounding only three bells, when ten were intended. Whether the signal man was at fault ix doubtful, but it is a fact that the apparatus had worked I)adly that morning, and before the aecident a man had been stationed to signal with the bell-rope in case the battery did not work. There is little confidence in the electric mode of signaling, and, I believe, it is not in use now in any mine on the lode. A small wire hand-rope is used, and on the whole is safe and eonvenient. In looldng over this list of casualties it is evident that the accidents which possess most interest are those whieh have near or remote connection with the heat of the mines, ti-)r the latter are sinking with great rapidity, and becoming hotter each year. During the past eighteen months they have been deepened tbur hundred to six hundred ti~et, and it is diffieult to deny that the greater depth increases the chances of accident in minos which, in addition to the ordinary liabilities of nfining work, have the insidious and ever present etti~ets of hot air~ water and reek upon the l)hysical and mental condition of the men. While I have never myself doubted the ability of the exedlent managers to carry the works in these hot reeks down to the greatest depths that ~re antieipated fl)r mining in any region, I find there is widespread doubt in the West upon this subject. There is an impression that the Comstoek lode has nearly reached the end of the mining rope, and the reason usually given is that life cannot be sustained in the great heat of the lowest workings, which heat the popular mind loves
Sept, i 8 7 9 . ]
CA~ereh--l~Ti~ing Accident.s.
177
to exaggerate. The record 1 present in this paper should be sufficient to dispel such doubts. Out of 101 accidents twelve were directly caused by the heat or hot water. Undoubtedly the falls of men down a sha{~ have been caused sometimes by sudden exhaustion, due to the heat and steam h~ upcast shafts, but on looking over the accounts of the accidents of this kind, which are included in the above list, I cannot find any of them that show a connection with this cause. The casualties positively traceable to the heat are, therefore, twelve per vent. of the whole. Prol)al)ly the heat increa~ses the bad effects of powder fumes and natural gases, and by making repairs to the shafts more frequently necessary it adds indirectly to the occasions when disasters may occur. I also eontbss to the belief, which is not sustained by obserw~tions upon specific casualties, that some alh)wance should be made for a less active mental condition, a dulling of the faculties, and ,~ vertain recklessness to which the heat sometimes goads the men. On the other hand the heat makes them more cautious except when under momentary impulses, and I have never seen American miners more eareihl of the,nselves than in these mines. On the whole, the good and bad effects of the heat seem to nearly balance each other, and I think that an allowance of five per cent. for the casualties indirectly caused by the high heat would be sufficient. The specific cases which I present do not warrant even that allowance. The accidents recorded here relate to a time when the number of nfiners at work in the district was from three thousand to thirty-five hundred, including top men and underground men. Most of them worked eight hours, but some of" those on top had twelve hour shifts, and probably there was a constant force of nine hundred or one thousand men below. It is not possible to make a comparison between these casualties an~ the, anmunt of ore ralsed, as the practice is in statistics of coal mines,. fbr the reason that only two out of about forty mines were producing: much ore throughout the period covered by the list. The comparison can be made for those tw% the Consolidated Virginia and California, and is as follows for the year 1878 : Proportion to tons ore.
Number of accidents, Fatal casualties, Casualties not fatal, Tons of ore extracted,
10, 5, 8, 257,718.
1 to 25,771 1 to 51,542 1 to 32,214
Of the casualties included in the list for twenty-two months there WHOLE No. VoL. CVIII.--(THIRI) SERIf, Vol. lxxviii.)
13
178
Cht~rch
MiMrt9 Ae,'.ident.~.
[aour. Frank. Inst~
were ill these two mines twenty-five 'w.eidents, twelve fatal, and eighteen not iMal easualtics, or twenty-five, twenty-two aml a halt', and twenty-six I}el• vent. of the whole. Frmn all these fiu,ts I conclude that iuereasing heat will not debar :the Comst()(d< mines fl:Om continuing to tho gr(,at(~st depths xvhieh are .L.mlsitlered practicable in the existing m!iustn/ent ()i' mining apldianees to the market vahm oF mining products. It is true that an air temperatm'e of" 1t)8 ° Fahr. is c'omm, m at the 2000 feot level, while 11(1° and 112 <~'are not infrequently ol)serw~d, and that a drift wl,idl showed a ~emperatm'e of 123 °, 126 ° and 128 ° Fahr., 'recording to dift~rent relmrt.~, ]~Ls proved to be tim most deadly on the lode. i t is also true that the temperature of the ro~'k is invreasing, and with it tlmt ,~f the air, and at stone dept] b tbr the calculation of whi('h tlmr(, are abs0iutelv no data, tim tempe.rature of this drift may be expected to prevail throughout the lode unless the present conditions change. But flfi~ being an air temperature, it is always 1)ossible to mitigate it by artificial means. I t is already observable that drifts 1800 feet below the surface may show a much higher heat than others -100 fi~et below them. lligh temperature is largely a matter of locality and tempora W emulitions, and by vari,us expedients it may be confined to its l~alities~ or combated in other ways. Deep mining, by extending the line of work through the moving hanging wall, and compelling increased repairs to shafts, will perhaps ~ M to heighten the already great fl'equeney of fidls of men. In ~ddition to the heat , the peculiar mode of timbering in s(tuare :sets, the almost exclusive use of nitroglyeerine powders, the neeessity o f tYequent repairs to shaft timbers, the incessant movement of the rocks through which the shafts are sunk, making accidents in hoisting more than ordinarily frequent, and the necessity of transporting large •laantities of rock through narrow gangways entirely by human labor, :are the conditions in which mining on the Comstoek may l)e said to suffer rather more than the usual liability to danger. Two of these eauseg both eonneeted with the movement of the groined, may be expected to h~er~se with depth. Together with lain heat they comprise forty per e,,~zat, of the whole number of a('eidents, and we may therefore sum up ,,)~r conclusions by saying that the. conditions of deep mining will iinerea~e tbr~y per cent. of the causes which lead to casualties, and will ' ite~ve sixty per cent. unaffected. What the amount of this increase will he emmot be ibretold, and indeed cannot be estimated until an ore body
Sept., 1879.]
1'he Cbmpa.~s.
179
has been fi~und and worked at great depth. So far tile year 1879, whi(:h is pre-eminently one of deep sinking oil the Comstock, has been remarkably free fi'om casualties. The administration of the mines is excellent, and the oversight ample. Though there is no declared law, I observed that an accident wa~slikely to be tbllowed by the discharge of some miners, and several times the ,suitbrcrs went 1)ef'(}re a magistrate and made oath that they were not only entirely innocent of negligence, but absolutely ignorant that there was any danger impending, or that there was any one near who could be injured if an accident should take place. The managers seem to have crone to the conclusion, which guides the framers of some Euro}~ean mining laws, that accidents will not cease until the damage is assessed on every one in the neighborhood of the casualty, innocent or guilty. The 5[iners' Union is an active and powerful body, and does not hesitate to express an Olfinion on the conduct of the mines.
The C o m p a s s . - - T h e secret of the steadiness of a large compass is the longness of its vibrational period, and a small card would have the same steadiness as a large one if its vibrational period were the same. How little this is known is illustrated by the methods of procuring steadiness in common use. In some (as in the Admiralty !' J " card, provided for use in stormy weather) there is a swelling in the middle of' each of the steel needles to make them heavier; in others heavy t)ra~ss weight~s are attaehed to the compass cards as near the centre as may be, being sometimes, for instance, in the 'form of a small bra~ ring of about an inch and a half in diameter. Another method, scarcely less scientific, is to blunt the bearing-point by grinding it or striking it with a hammer, as has not unfrequently been done to render tile compass " less lively," or to fill the cup with brick-dust, as is reported by the Liverpool Compass Committee to have been once done at sea by a captain who w~s surprised to find afterwards that his compa~ could not be misted within a couple of points. All, these methods are founded on the idea that friction on the bearing-point is the cure for unsteadiness. In reali W fl,ietion introduces a peculiar unsteadiness of a very serious kind, and is very ineffective in remedying the propeL" unsteadiness of which something is essential and inevitable in a corn pass on board a ship rolling in a heavy sea and steering on any other course than due east or due west.~Sir IV. Thompson.