172 



NATURE 



\_Dcr. 23, 1880 



It would be impossible to controvert all the statements 

 that Mr. Plimsoll makes regarding the properties of 

 tire-damp, its tendency to rise to the highest point, and 

 so on ; he has supplied himself with all the knowledge 

 necessary to understand its behaviour when it is found 

 in easily manageable quantities. But what are we to 

 think of his proposal when we come to deal with such quan- 

 tities as 1000 and 2000 cubic feet per minute ? Two hours 

 .ifter the explosion at the Naval Steam-Coal (Penygraig) 

 Colliery we estimated the amount of fire-damp coming 

 up the upcast at iioo cubic feet per minute, and this is 

 doubtless the normal quantity when the colliery is at 

 work. Dinas Colliery, which adjoins the last-named one, 

 always produ;ed about 1000 cubic feet per minute for 

 some years before the explosion on January 13, 1879; 

 Llwynypia Colliery, which adjoins the Naval Steam-Coal 

 Colliery on the other side, produced 2000 cubic feet per 

 minute for some years, but its output of coal is now less, 

 and consequently its production of gas has decreased. 



But where does this gas come from, and how is it dis- 

 posed of.? In following one of the subdivisions of the 

 air-current from the point where it leaves the main in- 

 take air-current to the point where it returns to the main 

 return air-current we observe the following phenomena. 

 On reaching the first working place the air is still appa- 

 rently as pure as it was when it left the surface ; about 

 the fifth or sixth place it begins to show the first symptoms 

 of gas on the small flame of a glass safety-lamp (it is 

 still invisible in a Davy lamp) ; at the tenth place the 

 cap is quite apparent even to the unpractised eye ; at the 

 fifteenth place it is say ,''0 of ^n inch in height, and at the 

 twentieth place it is a j of an inch. This is enough, and 

 the current returns towards the upcast shaft without 

 passing through any more places. At the point of its 

 junction with the main return air-current its cap remains 

 exactly the same as it was when it left the last face. We 

 have ourselves verified these observations hundreds of 

 times in different mines. The number of places through 

 which the air must pass in order to obtain a given pro- 

 portion of gas varies according to the rate at which gas 

 is produced in the mine in c^uestion, and the volume of 

 air passing along the faces. 



In the most fiery mines we can generally follow the 

 air-current from the surface, and return with it again 

 to the surface after having passed along the working 

 places without having seen the least accumulation of 

 explosive gas. This is the rule ; a cavity left by a fall of 

 roof and containing explosive gas is the exception, and 

 not only is no work allowed to be carried on near it, but 

 means are taken to ventilate it as quickly as possible. 



How then could Mr. PlimsoU's method be applied under 

 these circumstances ? Should we slacken the ventilation 

 in order to give the gas time to rise to the roof, and 

 after it got there to give it a chance of finding its way to 

 a sump excavated for it somewhere or other ? If so we 

 should have streams of explosive gas travelling along the 

 roof of the working places, and our dangers would be 

 increased a thousandfold. We do not know what kind 

 of mines those are in which Mr. Plimsoll has seen a 

 stratum of explosive gas along the roof of the airways, 

 but we should prefer not to have anything to do with 

 them, even were his method applied for the purpose of 

 drawing off the gas. 



Let us take the explosion that has just occurred in the 

 Rhondda Valley as an example. About ten months ago 

 the two shafts, which are about 1 1 1 1 yards apart, and 

 over 400 yards deep, were connected together by an 

 approximately straight heading, which is driven nearly 

 level in coal from each shaft for say 520 yards, and 

 descends the slope of a fault for 60 yards. The coal in 

 one shaft is 30 yards below the level of that in the 

 other shaft, and the surface of the ground at the top 

 of the former shaft is 188 feet higher than at Ihe latter. 

 The fault forms a natural boundary between the workings 



of the two shafts, and, except for purposes of ventilation 

 and communication, they were treated as distinct collieries. 

 The workings are ranged on each side of the straight 

 heading, there being four districts at the lower level 

 (three on the right hand and one on the left, looking 

 towards the higher shaft), and one district at the higher 

 level (on the right hand side, looking in the same direc- 

 tion). The natural direction of the air-current is from the 

 lower to the higher shaft. The natural air-current gives 

 a volume of about 30,000 cubic feet of air per minute at 

 the present moment, and we are informed that when the 

 fan was at work the volume was between 60 and 80,000 

 cubic feet. The envelope of the fan was destroyed by 

 the explosion, and the natural ventilation had to be de- 

 pended on for the explorations so far as they have been 

 carried. 



Soon after midnight on the morning of Friday last there 

 were somewhat over one hundred men and boys busily 

 employed underground : five were at the bottom of the 

 upper shaft, four at the bottom of the lower shaft ; seven- 

 teen or so were on the straight heading about half-way 

 between the fault and the upper shaft ; twenty-four were in 

 the left-hand workings of the lower shaft ; several gangs of 

 from three to six were in each of the other three small 

 districts of the lower workings ; fifteen or so were in the 

 right-hand workings constituting the only district in the 

 upper pit ; some were cutting coal, others were blasting 

 down roof, some were filling rubbish, others were stowing 

 it into empty places, and here and there a horse and his 

 driver were proceeding along the roadways with short 

 trains of full or empty waggons. 



No explosive accumulation of gas is said to have been 

 found in the mine when it was examined a few hours 

 previously, and two men, who came up only a few minutes 

 before the explosion, had not heard of any unusual oc- 

 currence. The mine is a very dry one, and there is 

 abundance of very fine coal-dust to be found everywhere 

 on the roadways. 



A sudden shock was felt ; a veritable hurricane swept 

 through every passage and every open space communi- 

 cating with the air-ways ; a " darkness that might be 

 felt" ensued for an instant, then a gleam of brilliant light 

 accompanied by a shower of molten and red-hot dust, 

 then darkness again, and all was still. 



During the interval between the raising of the dust and 

 the passage of the flame some of the men, who evidently 

 knew what had occurred, pulled their coats over their 

 necks and mouths and staggered outwards, but fell after 

 they had gone at most six or eight yards ; others, as we 

 have said, knelt down, covered their faces with their 

 hands, and buried their mouths in the dust and small 

 coal on the floor ; the terrified horses made a few mad 

 plunges, and then the Angel of Death breathed upon 

 them all, and they remained transfixed in the positions 

 they had assumed at that fatal moment. Only five men 

 who were engaged in workings close to the downcast shaft 

 escaped alive. They were rendered insensible by the 

 after-damp, but recovered consciousness before the ex- 

 ploring parties reached them, having been revived by the 

 fresh air which immediately flowed into the downcast 

 shaft after the explosion was over. 



We ask now where was the fire-damp accumulated 

 that could produce so widespread an explosion, and at 

 what part of the colliery would l\Ir. Plimsoll have placed 

 his apparatus for the purpose of pumping it out? 



The flame ramified into every district of workings 

 both in the upper and lower pit, and left unmistakable 

 tokens of its presence in the form of crusts of coked 

 coal-dust on the timber, on the coal, and on some of the 

 men's bodies. 



It is evident that Mr. Plimsoll has remained un- 

 necessarily ignorant that many men have been engaged 

 in working out the problem he has attempted to solve. Let 

 him go back to the many volumes of Parliamentary evi- 



