medy. 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 1813, 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
arrested, began a minute chemical examination of fire-damp. He found
that carburetted-hydrogen gas, even when mixed with fourteen times
its bulk of atmospheric 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
increasing 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 explode 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
discovery of the safety-lamp to the Royal Society in 1815. 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.

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