56 ON THE FIRE-DAMP OF COAL-MINES, 



it, a lantern of this kind can be made to project light in a 

 straight line to a great extent, and illumination may be thrown 

 into a passage, or along the side of a wall which is to be work- 

 ed, by its being placed at one extremity. This may not only 

 have the advantage of economy, but of greater safety, so as to 

 render this method proper to be employed on this account 

 alone, independent of any other consideration ; for the lamp 

 being placed at some distance from the miner, the risk is 

 avoided from the concussion arising from his working, from 

 any fall from the roof, or from the sudden discharge of the in- 

 flammable gas from any opening in the coal. Illumination 

 may also be thus obtained, in situations where, from imperfect 

 ventilation, it is difficult to support the combustion of a lamp, 

 such as the close extremities of passages or of new workings. 

 These are the very places, too, which are more peculiarly liable 

 to the accumulation of the inflammable air ; and in both re- 

 spects, therefore, the advantage is obvious, of a mode by 

 which, where the direction of the working admits of it, (which 

 it will almost always do to a certain extent,) light may be 

 thrown from a distant spot, where the same difficulty and the 

 same hazard do not exist. Lastly, In ascertaining the state of 

 the air in passages where danger is suspected, or in exploring 

 them after the accident of an explosion, the same method will 

 give greater safety. Where a more diffused light is wanted, 

 this is easily attained by the surface of the lens being more or 

 less scratched. 



Note E. page 45. — When the workings of a mine are car- 

 ried to a considerable distance from the course of the current 

 of air, without a corresponding shaft being made, the ventila- 

 tion becomes very imperfect. In this case, it is stated in a ve- 

 Ty candid communication by Mr Scott, (Edinburg7i Journal, 



December 



