S8 IIER OES OF JN VENTION AND DISCO VER V. 



drawn to the contriving of a lamp, seeing it required a given 

 time to pass over a given distance. My idea of making a lamp 

 was entirely on mechanical principles ; and I think I shall be 

 found quite correct in my views from mechanical reasoning. 

 I knew well that the heated air from the fire drove round a 

 smoke-jack, and that caused me to know that I could have a 

 power from it. I also knew very well that a steam-engine 

 chimney was built for the purpose of causing a strong current 

 of air through the fire. Having these facts before me, and 

 knowing the properties of heated air, I amused myself with 

 lighting one of the blowers in the neighbourhood of where I 

 had to erect machinery. I had it on fire ; the volume of flame 

 was coming out the size of my two hands, but was not so large 

 but that I could approach close to it. Holding my candle to 

 the windward of the flame, I observed that it changed its 

 colour. I then got two candles, and again placed them to the 

 windward of the flame; it changed colour still more, and 

 became duller. I got a number of candles, and placing them 

 all to the windward, the blower ceased to burn. This then 

 gave me the idea, that if I could construct my lamp so as, with 

 a chimney at the top, to cause a current, it would never fire at 

 the top of the chimney ; and by seeing the velocity with which 

 the ignited fire-damp passed along the roof, I considered that, 

 if I could produce a current through tubes in a lamp equal to 

 the current that I saw passing along the roof, I should make a 

 lamp that could be taken into an explosive mixture without 

 exploding externally." After many experiments his third and 

 most successful safety-lamp was constructed, and tested on the 

 30th November, 18 15, before he had ever heard of Sir Humphry 

 Da\y's experiments. After being exhibited before the Literary 

 and Philosophical Society of Newcastle, it came into use in the 



