THE SAFETY-LAMP.
Many regard the invention of the miner's safety-lamp by Sir Humphry Davy, George Stephenson, and Dr. Clanny—for they are all the productions of about the same period—as improvements in the art and science of mining, and regard those inventors as benefactors in saving life. But however valuable the safety-lamp has been, and still is, under certain circumstances, and however worthy of honor the distinguished inventors may be, we do not consider that the Davy lamp has conduced to the safety of human life, or the advancement of the science of mining in the proper direction, if we admit the results to be good evidence.
Had this invention been followed by others of a kindred nature, directed against the great prime evil, instead of providing antidotes, it is probable that safety-lamps would long ago have taken the place they were intended to occupy,—to show where the danger existed, and to enable the miner to provide against it. But, instead of this, the "Davy" has made our miners indifferent to the danger ; it has given them the means of living and working in the midst of the fiery atmosphere, and they seem to ask no more. They are able by means of the lamp to face the danger and brave it for a time with impunity, but in reality it decreases their security. Had this means not been pro vided, efforts would have been directed against the evil itself, and the prime cause of the danger would have been removed, instead of being entailed as a constant menace. The consequence has been that the number of deaths by gaseous explosions in mines has been increased by its use.
The safety-lamp is, nevertheless, a valuable invention or addition to mining science, and, if properly used, might be considered a benefit to the miner. But the practice of working deep and fiery mines entirely with the safety lamp, of sending hundreds of men to their daily work in an element more explosive than powder, and which the slightest accident or carelessness might ignite, cannot be too strongly condemned. Mines that cannot be worked otherwise ought to remain idle until means be devised to render them safe. This can be effected; and it should be considered a crime to send men to imminent death where it is neglected.
We know it is impossible to keep any deep and extensive mine entirely clear of ex plosive gas; but there is a vast difference between the jets of gas which are constantly escaping, and which may occasionally lie in the "headings," where currents cannot be carried, and the accumulations of the whole mine.
The danger and the difficulty can be overcome only by removing the prime cause; and the safety-lamp cannot be considered of any real benefit to the miner so long as it diverts attention from the main object. It may be of temporary service to both miner and operator; but, if used as a permanent preventive, it ultimately proves false to both, and brings ruin and death, instead of profit and safety.
The Davy lamp was introduced in 1815, and the "Geordie" of Stephenson and the Clanny lamp of Dr. Clanny were invented and made use of about the same time. The first safety-lamp, however, was made by Dr. Clanny, in 1814; but it was too large and cumbrous for general use, being insulated by water, and fed by complicated contrivances.
The conclusions arrived at by both Davy and Stephenson were the results of practical experiments and scientific deductions. They both discovered that carbonic acid or azote (nitrogen) extinguished flame,—Stephenson by the fact that the burned air from a candle extinguished a jet of burning gas, and Davy by determining that one part of carbonic acid with seven parts of carburetted hydrogen, or one part of azote with six parts of fire-damp, rendered them non-explosive. They also found by experiment that flame would not pass through small tubes or holes. Davy made use of iron-wire gauze of one-fortieth or one-sixtieth of an inch diameter, with 28 wires or 784 apertures to the square inch; while Stephenson at first used punctured tin plates, but afterwards improved his lamp by using glass and wire gauze. The difference in the Davy lamp and the Stephenson lamp is this:— In the Davy the air has access through the meshes of the wire gauze on all sides, and when immersed in an inflammable mixture the cylinder is filled with flame, and soon becomes red-hot: the oil ceases to burn, for want of oxygen, but the gas remains ignited while the lamp continues in this condition, and the passage of the flame is prevented only by the radiation of heat from the wires. In this condition it is dan gerous.