412 A Geognostical Sketch of [Dec. 



tinually on the increase, on account of the continually increasing 

 expense of mining. 



I have already on a former occasion stated my opinion respecting 

 the mode of working the collieries practised here^ and indeed all 

 over the kingdom ; and have seen nothing in my late visit to induce 

 me to alter that opinion. Delicacy would have prevented me from 

 venturing to state that opinion ; but the numerous lives sacrificed to 

 the present system, and the increase of the danger as the mines get 

 deeper, render silence on the subject improper, if not criminal.* 



-2. The sand-stone in this formation is known by the name of 



* From a letter in the Philosophical Magazine for October, p. 303, subscribed 

 An Engineer, it would appear that some observations of mine in the Annals of 

 philosophy, vol. iii. p. 431, have been misunderstood by the class of men t6 

 ■whom they were chiefly directed. I shall therefore take this opportunity of stating 

 them more explicitly. 1. tire-damp has been repeatedly analysed by myself aud 

 others, and found always to consist of pure carbureted hjdrosren gas without any 

 mixture of sulphureted hydrogen gas. I have spent many hours in coal-mines 

 without ever perceiving the smell of sulphureted hydrogen gas. These fact* induce 

 we to believe that sulphureted hydrogen gas is Dot formed in coal-mines. Now I 

 do not see how iron pyrites (a compound of iron and sulphur) can contribute to the 

 formation of carbureted hydrogen (a compound of carbon and hydrogen). But if 

 this Engineer can show us in what manner pyrites can contribute to this formation, 

 he will he in the right to say that Cite explanation of my Newcastle correspondent 

 was verv probable ; but he has no right to draw any such inference till such au 

 explanation is offered. 2. 1 spent 25 years of my life in a coal country, and in 

 difl'erent parts of it, at Stirling, in Fife, in Mid-Lothian. During 12 years of that 

 time I was interested in the subject of coal-mines, in consequence of the branch 

 of science to which I had attached myself. I never during that time heard of a 

 single explosion from fire-damp in any of these mines ; yet if they had occurred I 

 think 1 must have heard of it. About Glasgow explosions from fire-damp never 

 (afce place. This is the case also at Tweedmouth ; but explosions take place at 

 Borrowstuiiness, at Newcastle, in Staffordshire, and in the neighbourhood of 

 Bristol. Now in Mid-Lothian, at Stirling, Glasgow, Tweedmouth, the mines are 

 shallow; at Borrow stonness, Newcastle, Staffordshire, Bristol, they are deep. 

 ■\Vhat other inference can be drawn from this lha:i ihat tire-damp only accumulates 

 in deep mines. I conclude from it that fire-damp is formed very slowly. Weeks, 

 probably months, or even years, elapse, before it is evolved in sufficient quantity 

 to become dangerous. The fire-damp in deep coal-mines has probably been accu- 

 mulating; forages; and unless the mode of ventilation were very imperfect indeed, 

 it would make its escape before it became dangerous in point of quantity. 3. The 

 Engineer observes that I do not seem to be aware that the accidental and progressive 

 falling of the roofs of most coal-pits occasions numerous higher places, or dome- 

 like cavities, above the old hollows, and even over the gates and passages in too 

 many instances, wherein it is impossible to prevent the lighter ga»es, where they 

 abound, from accumulating. Now I beg leave to inform this Engineer that 1 am 

 perfectly aware of all this, and more than this ; and that these are the very defects 

 in the present system to which 1 alluded. As long as they exist it will be impos- 

 sible to free coal-pits from fatal accidents from fire-damp. The coal engineers, I 

 know, universally affirm that these are defects which it is impossible to remedy ; 

 but I own thai I am not disposed to admit of such sweeping conclusions, nor to 

 believe that the art of coal-mining has already reached its utmost limit of perfec- 

 tion. It would be convenient for these gentlemen to be provided with a demon- 

 stration of such impossibility of improvement. If they were to apply to Dr. 

 Oliothus Gregory, who has a knack of demonstrating impossibilities, it is probable 

 that he w oulil supply them to their satisfaction. I admit without hesitation that 

 the present system is so bad that it does nut admit of remedy in old collieries; but 

 this is no reason why new collieries should not lie constructed on more scientific 

 principles. I should think more highly of ^« Engineer than I do at present, if he 

 would turn his attention to improving the present wretched mode of ventilating coal- 

 mines, instead of giving his opinion on topics which he obviously has not examined. 





