The invention of the safety lamp, in 1815, is probably the most important event of the early part of the century. Previous to this the miners fired the gas in the “rooms” with their candles, which were raised toward the roof with the aid of a long pole, the miners lying flat on the floor of the level to escape the blaze, and sometimes putting on wet jackets to avoid being scorched. As first invented by Davy, the safety lamp consisted merely of a cylinder of wire gauze surrounding the flame, much as the flame is surrounded by a glass globe in the modern lantern, except that the diameter of the cylinder did not exceed two inches. This was based upon the theory that the gas set on fire by the light would burn inside the gauze without heating it hot enough to ignite the gas outside. The principle was correct, and the lamp worked satisfactorily when carefully used under proper conditions. It was soon found, however, that in a strong air current, or if swung at a more rapid speed than six feet per second in an explosive mixture, the surrounding gas would be ignited. As a man walking naturally on the surface moves at a rate of between five and six feet per second, it will be easily seen that even were the speed considerably diminished underground,—and any one who has tried to follow a mine foreman through mine workings knows the speed slackening is slight,—a very slight swing of the arm would bring the rate of movement of the lantern up to the danger point. Another and a very unexpected factor in causing explosions with the new lamp also developed; and that was the great carelessness of the men who used it. Armed with this device, and deluded by the quietly burning flame, the miner would seat himself upon a pile of coal, draw forth his pipe and fill it, and deliberately open the gauze to light it. As a consequence, for a time after the introduction of the safety-lamp, the number of accidents from explosions increased. This latter difficulty, the recklessness of the miners, was presently overcome by having the lamps locked, and by depriving the men of all matches before admitting them to the mine. An improved lamp, introduced by Clanny, wherein the lower part of the cylinder was replaced by glass, partially protected the flame from strong air currents, and also gave a better light. Later, Müseler added an interior sheet iron chimney, which divides the air current so that the hot air does not strike directly against the gauze, and the lamp as thus improved is very largely used, especially in Europe.
SINKING, DRIFTING, AND STOPING WITH THE INGERSOLL-SERGEANT DRILLS.
In 1831 the safety fuse was invented, a train of powder having been used before this for firing the charges. The same year a patent was granted to Moses Shaw of New York for an electrical device to fire several charges at once. It was at about this time, too, that the man-engine was invented in Germany. Some miner, noticing the slow and steady up and down motion of the long rods which operated the pumps in the Cornish system, had conceived the idea of nailing steps on to them at intervals, and riding up and down. As mines grew deeper and the time and labor required for the men to get down to their work increased, a special engine, utilizing an improvement of this device, was employed for raising and lowering men. This “man-engine” consisted of two parallel beams, moving slowly up and down the shaft with a reciprocating motion, the length of the stroke being about twelve feet. Upon these beams small platforms were nailed at distances equal to the length of the stroke. The miner wishing to descend stepped upon the top platform of one beam as it started on its down stroke. At the end of this stroke he found himself twelve feet down the shaft, on a level with the second platform of the other beam, which had in the mean time been coming up, and he stepped across on to this, which now began its down stroke. Thus by constantly stepping from one rod to the other at the completion of each down stroke, he was conveyed to the bottom. By reversing the process he was raised to the surface.
INGERSOLL-SERGEANT DUPLEX STEAM-ACTUATED AIR COMPRESSOR.
In general, mining progress was slow up to the middle of the century. The production of the baser metals, here and abroad, increased gradually with the demands of the mechanic arts, but it was not until the middle of the century that this factor, joined with the improved methods of transportation, and of metallurgy, gave to mining that impetus which, though through alternate recurring waves of prosperity and stagnation, carried it forward until the annual expenditure for technical skill, machinery, and supplies used in the industry is estimated to-day at one thousand million dollars.
The first mining excitement in the United States occurred in 1829, following the discovery of gold in the South; but these fields soon declined in importance without resulting in any improvements to mining methods and machinery.
The next mining fever resulted from the inauguration of work upon the copper properties at Keweenaw Point, Mich., in 1845. This caused the first mining-stock speculation in this country, and it is interesting to note that the century closes with a repetition of this same fever, founded upon almost the same ground. Yet the conditions have changed wonderfully. Upon the then barren peninsula, whitened with the tents of speculators and geologists, has grown up a multitude of towns, filled with thousands of people whose labors are performed at a depth of nearly a mile under ground. Thousands more transport the ore to the mills, separate the copper from the rock, and cut timber for the mines; while yet other thousands prepare food and clothing and shelter for all these. During 1898, the copper mines about Lake Superior produced nearly 160,000,000 pounds of copper, and paid in dividends $6,490,000.
