So thoroughly provided with all needful commodities is the great house of the world, that, in order to obtain whatever we desiderate, seldom is aught else requisite than a distinct realization of our want and a determined effort to supply it. In working mines, one of the difficulties with which the excavator has to contend is the influx of water. The effort to remedy this evil gave birth to the steam-engine; and, with the relief afforded by the steam-pump, many mines are easily and profitably wrought which otherwise must have long since become mere water-holes. But a worse enemy than water encounters the collier, in the shape of fire-damp, or inflammable gas. Formerly, in quarrying his subterranean gallery, the axe of the unsuspecting pitman would pierce a magazine of this combustible air, and unlike water, there being nothing to bewray its presence, it filled the galleries with its invisible serpent-coils; and it was not till a candle approached that it revealed itself in a shattering explosion, and a wretched multitude lay burning and bleeding along its track—a fearful hecatomb to this fiery dragon. What was to be done? Were the blast furnaces of Wales and Wolverhampton to be extinguished, and were household fires to go out? Or, for the sake of a blazing ingle and good cutlery, were brave men still to be sacrificed to this Moloch of the mine? The question was put to Science, and Science set to work to solve it. Many good expedients were suggested, but the most ingenious was in practice the simplest and safest. It was ascertained that a red heat, if unaccompanied by flame, will not ignite the fire-damp; and it was also known, that the most powerful flame will not pass through wire-gauze, if the openings are sufficiently small. A lamp or a candle might, therefore, be put into a lantern of this gauze, and then plunged into an atmosphere of inflammable air; and whilst the flame inside the lantern gave light enough to guide the laborer, none of that flame could come through to act as a match of mischief. And now, like a diver in his pneumatic helmet, the miner, with his “Davy,” can traverse in security, the depths of an inflammable ocean.