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 SIR HUMPHRY DAVY 279 fire-damp occurred within a coal-mine in the north of England, so dreadful that it destroyed more than a hundred miners. A committee of the proprietors besought our chemist to provide a method of preparing for such tremendous visitations ; and he did it. He tells us that he first turned his attention particularly to the subject in 1815 ; but he must have been prepared for it by the researches of his early years. Still, there appeared little hope of finding an efficacious remedy. The resources of modern mechanical science had been fully applied in ventilation. The comparative lightness of fire-damp was well understood ; every precaution was taken to preserve the communications open ; and the currents of air were promoted or occasioned, not only by furnaces, but likewise by air-pumps and steam apparatus. We may here mention that, for giving light to the coal-miner or pitman, where the fire-damp was apprehended, the primitive contrivance was a steel-mill, the light of which was produced by contact of a flint with the edge of a wheel kept in rapid motion. A "safety-lamp" had already, in 18 13, been constructed by Dr. Clanny, the principle of which was forcing in air through water by bellows ; but the machine was ponderous and complicated, and required a boy to work it. M. Humboldt had previously, in 1796, constructed a lamp for mines upon the same principle as that of Dr. Clanny. Davy, having conceived that flame and explosion may be regulated and ar- rested, began a minute chemical examination of fire-damp. He found that car- buretted-hydrogen gas, even when mixed with fourteen times its bulk of atmos- pheric air, was still explosive. He ascertained that explosions of inflammable gases were incapable of being passed through long, narrow metallic tubes ; and that this principle of security was still obtained by diminishing their length and diameter at the same time, and likewise diminishing their length and increas- ing their number, so that a great number of small apertures would not pass explosion when their depth was equal to their diameter. This fact led to trials upon sieves of wire-gauze ; he found that if a piece of wire-gauze was held over the flame of a lamp, or coal-gas, it prevented the flame from passing ; and he ascertained that a flame confined in a cylinder of very fine wire-gauze did not ex- plode even in a mixture of oxygen and hydrogen, but that the gases burned in it with great vivacity. These experiments served as the basis of the safety-lamp. Sir Humphry Davy presented his first communication respecting his discov- ery of the safety-lamp to the Royal Society in 181 5. This was followed by a series of papers, crowned by that read on January 11, 1816, when the principle of the safety -lamp was announced, and Sir Humphry presented to the society a model made by his own hands, which is to this day preserved in the collection of the Royal Society at Burlington House. There have been several modifications of the safety-lamp, and the merit of the discovery has been claimed by others, among whom was Mr. George Ste- phenson ; but the question was set at rest in 181 7 by an examination, attested by Sir Joseph Banks, P.R.S., Mr. Brande, Mr. Hatchett, and Dr. Wollaston, and awarding the independent merit to Davy. It should be explained that Stephenson's lamp was formed on the principle of