AND ON PREVENTING ITS EXPLOSION. 45 



want of any proper method to ascertain the extent of danger. 

 In many of them the accumulation of the fire-damp was sus- 

 pected ; it was in trying to ascertain this that the explosion 

 happened, and it is. astonishing to observe, in some cases, the 

 extreme imprudence with which this was done, by approach- 

 ing with a common candle. In mines peculiarly liable to 

 such accidents, it might be well to have a regular system of 

 making such trials at stated periods. And this is more neces- 

 sary, when it is considered, that all methods of lighting that 

 may be proposed, are, strictly speaking, only calculated to les- 

 sen the danger from accidental firing of the gas; and that, irr 

 one point of view, they are a source of hazard, as giving the 

 idea of greater security, and being liable, therefore, to lead to: 

 less strict attention to ventilation. 



When the accumulation of gas to a dangerous extent is as- 

 certained, it may be drawn off by various methods. A com- 

 munication may be formed with a part of the mine in a state 

 of thorough ventilation, and the rapidity of the current of air 

 might be increased. Or, the foul air might be pumped out by, 

 a steam engine, or by an exhausting machine, such as that pro- 

 posed by Mr Taylor *, brought to act on any particular part. . 

 (Note E.) 



It is not necessary, however, to enter on the details of the 

 system, which, with regard to several of the contrivances, are 

 indeed sufficiently obvious, and which might farther be varied 

 by local circumstances, and be improved by a knowledge of 

 these, and by experience. My object has been, merely to state, 

 the general method, and explain its principles, with any col- 

 lateral observations which appeared to me to be of import- 

 ance. 



It 



* Thomson's Annals, vol. iii. ; or Philosophical Magazine, vol. xxxviii. 



