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the atmosphere cannot produce inflam-mation ; for minute particles of ignited solidmatter have no power of inflaming thefire-damp; and I have repeatedly blownfine coal dust mixed with minute quantitiesof the finest dust of gunpowder through thelamp burning in explosive mixtures with-out any communication of explosion.

A few complaints have been made of thefeebleness of the light of lamps alter theyhave been some time used, in consequenceof the tissue being choaked up by coaldust. But by means of a brush this evilmay be removed. And in some experi-ments, that I made with Mr. Buddie, inthe Wall’s-end Colliery, the light of a singlegauze lamp furnished with a tin-plate re-flector, was found to be superior to thatof a common miner’s candle, and the lightof a lamp without the reflector, nearly equalto it; and almost double to that of the steel-mill at its greatest intensity of light. Thetrials were conducted by determining thedistance at which an object was visiblewith the different species of light, and con-sidering the intensity of the light directlyas the square of the distance.