206 THE FIRE-DAMP'S FAMILY CIRCLE. 



with a severe burning, to tell the tale. Again, a father and 

 two sons were burned to death through using a Davy lamp 

 at Sutton-low-bottom pit, in consequence of their having 

 agitated the air to clear out their working places. 



In both cases the lamp was found perfect after the acci- 

 dent. Were it necessary, other examples of the effect of air- 

 currents in driving flame through the gauze meshes of the 

 safety-lamp might be cited. None, however, but the most 

 prejudiced in favour of Davy's lamp will deny that its facility 

 of explosion when exposed to currents is a much greater 

 drawback to its utility than was suspected in the days of its 

 early existence. 



Are air-currents the only agencies which can interfere 

 with the safety of Davy's lamp ? Most probably not. As- 

 suming fire-damp to be a mixture of light carburetted hydro- 

 gen and atmospheric air nothing more experiment would 

 seem to justify us in saying that, while perfectly quiescent, 

 it is not susceptible of being exploded by the safety-lamp : 

 but it now turns out that fire-damp has by no means this one 

 invariable composition; it sometimes contains olefiant gas, 

 sometimes sulphuretted hydrogen and pure hydrogen ; either 

 of which is susceptible of ignition by contact with metal not 

 raised to so high a temperature as often occurs to the cage of 

 a safety-lamp. 



Again, the contingency does not seem to have presented 

 itself to Davy, that particles of coal are flying about in a 

 coal-mine ; and these, falling on the red-hot gauze of a safety- 

 lamp surrounded by explosive gas, may ignite and generate 

 a little focus of death-dealing flame. 



We come now to the consideration of other lamps, starting 

 on the invention of Davy for their basis, but modified so as 

 to avoid the weak points of the former ; and designated each 

 by the name of its so-called inventor. 



Once more I repeat, Davy shall have the credit of every 

 lamp which has a scrap of wire gauze in its construction. No, 



