THE THREE DEADLY MINE GASES The three principal gases encountered in mines are choke-damp, or carbonic acid gas; fire damp, or marsh gas; and after-damp, or carbonic oxide gas. Choke-damp is heavier than air and settles in the lower parts of a mine, just as water seeks the lowest level. It kills by suffocation. It may be dipped up with a bucket like water, and its presence may be detected by lowering a light into the cavity where it exists, as it will put out the flame immediately. Individual miners are killed by it, but it never explodes. Fire-damp is a most peculiar gas. If you mix less than 85 per cent of air with it or more than 95 per cent of air, it will burn but will not explode; but if it be mixed in the proportion of 88 or 89 parts air to II or 12 of fire-damp, the combination becomes one of the most terrible of explosives. Eternal watch fulness is the price of Photograph from U. S. Bureau of Mines HOW NOT TO PREPARE A BLAST This miner, pouring powder out of a jagged, pick-cut hole in his can, while his cap lamp burns brightly, is not only taking a chance with his own life, but with that of every other miner in the workings. This is a picture of what the miner should not do. But thousands of lives have been sacrificed by just such methods. safety. When the coal is blasted down, fire-damp pockets are often opened up, and the thin, trickling, hissing sound tells the miner what has occurred. Miners test the chambers, headings, and entries for fire-damp with a lamp. If the blaze becomes elongated and blue at the base, that gas is present. An explosion of fire-damp is one of the most terrible disasters that can occur in a mine. In an instant the dark, manmade caverns are lighted up from end to end by a lightning that beggars descrip tion. "The expanded gas drives before it a roaring whirlwind of blazing air," as one who has survived the catastrophe tells us, "which tears up everything in its progress, burning many a miner's body to cinders, entombing others, and, rushing to the shaft, it wastes its fury in the shower of dust and stones and timbers it blows high into the air." A tragic story might be written of mine disasters which fire-damp has caused and of the tens of thousands of miners who have given up their lives in such holo Many a mine mule has hee-hawed with delight as his life sentence to hard labor in an underground prison has been commuted by the arrival of electric transportation. The sharp-nosed sticks in the foreground are "sprags" to be stuck between the spokes of the car wheels to brake or "scotch" them. They have left their imprint upon the vernacular of the coal region, since to "sprag" a scheme is effectually to block it. causts; but as the years go by greater care is used, better ventilation is maintained, and the disasters, happily, are growing fewer. After-damp is one of the deadliest of all gases encountered in mines, but fortunately it does not occur except following fires. It is so subtle that the miner is powerless to escape its attack when he realizes its presence. Odorless, or possessed of a mere hint of violet, its victims experience an exhilaration at its onset that seems to them only a sensation of feeling unusually well; but so quick and deadly are its effects that before this feeling passes, the victim is wholly within its grasp. HAND METHODS PRODUCE ANTHRACITE In the anthracite region mining is still done principally by hand. Some jackhammer drills have been introduced and some electric coal-cutting machines; but hand methods still produce most of the anthracite. The jack-hammer drill is an instrument which bores the blast-holes by power. With one of these drills a miner is enabled to bore as many holes in one hour as he can bore in eighteen with a hand-drill. Among the illustrations of this article (see pages 414 and 416) will be found pictures of cutting machines, jack-hammer drills, mechanical shovelers, etc.-labor-saving machinery that is now working wonders in the productive powers of the miners. If space permitted we would follow our fine old Welsh guide up into the "kidney" of the mine and see a second layout of entries, headings, and chambers in a halfway station seam; we would contrast the new steel timbering of the mines with the old wood timbers coming from the South; we would stop to look at the mule stables, as clean and as sanitary as any stables you ever saw, with a sand-floored yard, where the sick ones may roll and rest to their hearts' content. But let us follow the coal up the shaft, and through the breaker in the case of anthracite, and through the tipple or dumping house in the case of bituminous. When we reach the top again, we note the layout of the breaker plant, where the coal is cleaned and sorted into the several commercial sizes. The first thing that impresses us is that the mine-owners. are almost as careful in saving coal as a miser is in hoarding his gold. The loaded mine cars are rolled off the cage by hand, and the breaker building is so situated that the cars run down to it by gravity. As the cars roll down to the breaker hoist, which may be either a vertical lift or an inclined plane, boys "sprag" or "scotch" them and let them down to the hoist one by one. Going up to the top of the breaker, we see the coal as it comes from the mine, with all its slate and culm, mechanically dumped, a carload at a time, upon the oscillating bars, which begin the process. of separating the coal from the worthless material and the assorting of the former into groups according to size. There are eight different sizes of coal now in general use-broken, egg, stove, and chestnut, which are the domestic sizes, and pea, buckwheat, rice, and barley, which are steaming coals. They range from four inches in diameter for broken to one-sixteenth of an inch for barley. Of course, there are as many pockets at the railroad tracks as there are grades of coal produced in a breaker, and as many chutes into the cars as are necessary to load every grade simultaneously. After the "bony" coal passes through the crushers and is broken up, it joins the procession of unseparated slate and coal down the several chutes. At one place it runs through a centrifugal slate picker, which is a striking contrivance that does the work of a jig in another type of breaker. There are dry breakers and wet ones, but this has no reference to the presence or absence of prohibition. Dry breakers are those where the coal comes from the mine fairly clean and goes through the breaker without being watered, either for the suppression of dust or for the washing of the coal. Also, there are breakers which separate the slate and culm from the coal by jigs rather than by centrifugal pickers. In these the coal as it comes from the mine is "jigged" up and down in water. The coal settles more slowly than the slate and culm and can therefore be skimmed off like cream from milk. In order that the miners may not be THE INCLINED-PLANE ELEVATOR OF AN ANTHRACITE BREAKER Photograph by J. Horgan, Jr. When the loaded cars are brought out of the mine they drift by gravity to an inclined plane. There a "barney," attached to a cable, pushes them to the top of the breaker where the coal is dumped. Then the cable is reversed and the barney acts as a brake in returning the cars to the bottom of the incline. ONE OF THE LARGEST COAL BREAKERS IN THE WORLD: KINGSTON, PA. The coal comes in at the rear of the breaker, on the top-story level. It wanders this way and that, first down this story and then the next, finally reaching the bottom minus its slate and dirt and separated into every size, from "broken" to "buckwheat." tempted to load too great a proportion of slate, there is a "court-house" at every breaker. The men are normally allowed 7 per cent for slate, but sometimes, when in a hurry to get a car loaded, they throw in a larger proportion of refuse. But they never know when one of their cars is going into the "court-house." This is a side track where an inspector examines the coal to see whether it is running to the proper percentages or not. If he finds that the miner has loaded too much slate, the latter is asked to take a day off. Two or three offenses result in a discharge. HANDLING BITUMINOUS COAL Handling bituminous coal after it coal after it leaves the mine is a much simpler process. Often it is sold as run-of-the-mine, in which case the mine cars are simply run up to the top of a building called the tipple, tipped over, and their contents dumped into a chute that leads to the railroad cars on the track below. If it is not shipped as run-of-the-mine, it is graded over a series of bar screens into lump, nut, and slack, each grade going into its own pocket ready to fall by gravity into the railroad car. Some of the bituminous tipples are large and elaborate affairs, capable of separating many thousands of tons of coal a day and loading it ready for shipment. Were space at hand, one might tell of the great culm banks that are being made to give up their coal; of the coal being dredged out of the rivers of the anthracite region, which was deposited there through decades of freshets and floods; of the superstitions of the miners, as, for instance, the dread of the white mule, which is harmless if the miner detects its ghostly approach, but certain to inflict a mortal bite if it is able to steal up unobserved. |