SAFETY-LAMPS. 193 



parison with which those of the preceding century were mere 

 wells. 



Along with increase of size, the ravages of fire-damp be- 

 came more terrible and more frequent. The times had gone 

 by when miners dared to chase it from place to place by 

 lighted candles tied to poles ; and the demand for coal was so 

 great, that an infested mine could no longer be abandoned 

 with the same indifference as in the earlier days of coal 

 extraction. 



At whatever cost and risk, the danger must needs be en- 

 countered ; experiments therefore began to be made with the 

 object of discovering, if possible, a means of producing light 

 adequate to the miners' exigencies, but unaccompanied with 

 fire, or at least the sort of fire which would ignite the explo- 

 sive gas. 



Amongst those illuminative expedients the only one which 

 ever rose into general importance was the steel-mill a cylin- 

 der of steel made to revolve against a piece of flint or pyrites. 

 Various other means, however some of them not a little- 

 curious were adopted on extraordinary occasions; amongst 

 which are noticeable the use of pyrophori or luminous chemical 

 bodies, luminous decaying wood, and decomposing fish: so 

 dire were the straits of coal-miners in their pursuit of coal 

 under difficulties. These expedients, however, constitute a. 

 proper introduction to a notice of safety-lamps. 





SAFETY-LAMPS. 



WHEN, in the beginning of the present century, a vast 

 development of machinery and an increased demand for coal 

 necessitated, to a proportionate extent, a deepening and ex- 

 tension of coal-mines, the ravages of fire-damp increased ; and 

 this class of accidents, from being a matter of interest to the 

 colliery districts alone, assumed a national importance. At 







