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when the fire-damp is burning in the lamp*choaks the upper apertures of the cylinder,and gradually diminishes the heat, by di-minishing the quantity of gas consumed.

I have seen wire gauze lamps in thehands of workmen, which they had usedfor several months, and which had beenoften red hot in explosive atmospheres, andwhich were still perfect.

Where an explosive mixture is in rapidmotion, it produces, as has been statedpage 97, much more heat: and in this-case the radiating or cooling surfaces of thelamp must be increased, or the circulationof air diminished,, Twilled gauze, or adouble or triple-fold of wire gauze on oneside of the lamp, or a screen of metal op-posite to the direction of the current, or asemi-cylinder of glass or of mica within,answers perfectly the object of preventingthe heat from rising to redness.

Single iron wire gauze of the kind used inthe common miner’s lamp, is impermeable tothe flame of all currents of fire-damp, aslong as it is not heated above redness; butif the iron wire be made to burn, as at astrong welding heat, of course it can be no