AND- ON PREVENTING ITS EXPLOSION. 45° 
want of any proper method to ascertain the extent of danger. 
In many of them the aceumulation 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, in 
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, striet 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 Taytor*, 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 obseryations which appeared to. me to. be of import-- 
ance. 
It 
* Tromsoy’s Annals, vol. iii. ; or Philosophical Magaziie, vol. xxxviii. 
