470 Fire-daynp. 



flexible tube reaching to the floor of the mine — on the principle 

 that the inflammable gas, being lighter than the atmospheric air, 

 will be found to occupy the higher station : but in fact, the 

 fire-damp is often disengaged from below ; which is a sufficient 

 objection (were there no other) to the use of this lamp. 



Another lamp invented by W. Brandling, Esq. was also ex- 

 amined by the Society, which, if there were now any necessity, 

 might be used for exploring dangerous places with safety. The 

 azote disengaged by the combustion is drawn out by double 

 bellows connected with the top ; and fresh air in consequence 

 rushes in throngh a flexible tube attached to the bottom of the 

 lamp, and of sufficient length to reach a current of pure air. 



In our last we gave a brief account of Sir H. Davy's safe- 

 lamp, and in our present nuoiber we have been enabled to lay 

 his communication to the Rcval Society, in an entire state, be- 

 fore our readers — a civciunstance that will prove gratifying to 

 several correspondents, who had expressed great anxiety to have 

 such information on the subject as might enable them to apply 

 it to practice. 



We have been favoured with a description of another safe- 

 lamp, also inserted in the present number, invented by a Mr. 

 Stephenson of Killingworth Colliery. In principle it is some- 

 what similar to Sir H. Davy's, and, considered as the invention 

 of a man of humble pretensions, has considerable merit, though 

 much inferior in construction to Sir Humphry's. It is rather a 

 curious coincidence, that two lamps at all approximating each 

 other in the means resorted to for obtaining the desired object, 

 ahould have been brought forward by difierent inventors ; for we 

 have every reason to believe that IVIr. Stephenson's as well as 

 Sir H. Davy's invention was perfectly original. The experi- 

 ments with Mr. Stephenson's lamp are, to a certain extent, sa- 

 tisfactory ; but, if we have rightly understood the communica- 

 tion of our correspondent, the absolute safety of the lamp was 

 not proved by them ; for pure Jire-damp appears to have been 

 thrown into it, which we know does extinguish flame; whereas 

 an explosive ■mixture should have been thrown in. 



We have seen Sir Humphry's lamp. He has succeeded in 

 bringing it to a state of absolute securily. This we saw proved 

 by a variety of experiments, in which the most explosive mix- 

 tures that could be formed were thrown into it, and the effect 

 invariably vva«, the extinction of the flame. It is impossible to 

 conceive any lamp more easy to be kept in order, while at the 

 same time it is as simple as any common portable lamp. 



Thus have the public been put in possession of a contrivance 

 which was long a desideratum, and which, not many months ago, 

 was ranked anaong those objects which, however desirable, could 



hardly 



