Coal and the coal mines

by Homer Greene

The method of cutting coal here is also peculiar to the soft coal mines. The miner has a pick with sharp, pointed ends, and with this he cuts a horizontal groove or channel, from two and a half to three and a half feet deep across the entire width of the entry or room. This groove is cut in that horizontal section of the face known as the bearing-in section. It may be in the bottom layer of coal, or it may be one or two feet above the bottom. The process itself is known as “bearing in,” “under cutting,” “holing,” or “undermining.” While he is at this work the miner must lie on the floor of the room, partly on his side, but with hands and arms free. When the horizontal groove has been completed a vertical groove similar to it in size and shape is made at one side of the face. These channels are sometimes cut with mining machines having compressed air for a motive power. This machine is small but powerful. It is placed on a low inclined platform at the face of coal, and is operated by a man called a “runner.” The inclination of the platform causes the machine, which is on wheels, to gravitate constantly toward, and to press against, the face of coal. The compressed air cylinder drives a piston-rod to which is attached a steel bit two inches in diameter projecting from the front of the machine. This bit strikes the coal with sharp, swift blows, chipping it out in small fragments, and eats its way rapidly into the seam. The compressed air is carried to the machine in an iron pipe from the compressing engine, which is located at the mouth of the mine. When a machine is used, seven men usually work three rooms. Three of these men are contractors or partners, three of them are laborers employed by the contractors, and one of them, called the “scraper,” is a laborer employed by the coal company. When the channel has been cut a sufficient depth and distance the coal above it is brought down either by wedging or blasting. If blasting is to be resorted to it will be unnecessary to cut the vertical groove. If the bearing-in channel was cut above the floor, the bottom coal is then lifted by wedging, and broken up. The miners do the cutting and blasting, the laborers break up the coal and load it into the mine wagons, and the scraper is kept busy cleaning the cuttings away from the channels and attending to the lamps.

The mine car track that is extended up into the room is of wooden rails, and the empty wagon is pushed in to the face by the laborers, and loaded and run out by them to the entry. Each wagon will hold a little more than a ton, and a mule will draw four wagons to the mouth of the drift. The wheels of the mine car are set close to each other, near the middle of the car, to facilitate its movement around sharp curves; the doors at the ends of the car are swung from a bar hinge at the top, and the cars are dumped in the same manner as those in the anthracite region. In some of the bituminous mines a small locomotive is used to draw the trains of mine wagons from the working parts of the mine to the opening. It will draw from twelve to sixteen wagons at a time, and will do the work of twenty mules. There is usually a separate split of the air current to supply the locomotive road in order to keep the smoke out of the working rooms.

When a set of rooms has been driven to its limit the miners then “draw back the rib;” that is, take out the pillars between the rooms, beginning at the face and working back. Posts must be used freely to support the roof while this work is in progress, about sixty or seventy being necessary in drawing a rib.

Ventilation here is obtained by both the fan and the furnace systems. In mines that are worked below water level fire damp often accumulates, but where the coal does not descend at any point below the water-level line, there is no probability that mine gases will be found.

As has already been said, the usual method of entry into the bituminous mines has been, and still is, by drift. But as the working faces of the mines recede farther and farther from the general lines of outcrop, it often becomes necessary to resort to the method of entry by shaft, and this latter method will doubtless in time supersede the former almost entirely. The main shaft, as it is now constructed, is usually about twenty feet long by nine feet wide, and has three compartments, two for hoisting and one for ventilation and pumping. It rarely exceeds two hundred feet in depth. The hoisting apparatus is much like that in use in the anthracite districts. Air shafts from fifty to one hundred feet deep, sunk for purposes of ventilation and drainage, are frequent, and stair shafts in which are fixed ladders for the purpose of ascent and descent, and which may be used as air shafts also, are not uncommon. Slopes, like those in the anthracite regions, are not usual here; the coal seams do not dip sufficiently to make them practicable. Narrow rock slopes are sometimes driven diagonally through the strata, at an inclination of twenty degrees or less, to strike the coal bed, but they are used only as air ways, as traveling ways for men and mules, and to serve as the “second opening” required by the mine law.

In the bituminous regions coal breakers are unnecessary and are unknown. As the vertical planes of cleavage of the coal are at right angles to each other, and as the stratification is nearly horizontal, the coal when broken takes a cubical form, large blocks of it being made up of smaller cubes, and these of still smaller, to an almost microscopic limit. All slate is separated from the coal as it is mined, and the refuse is piled up in the room.

The mine wagon is loaded only with good coal, and is taken directly from the mine to a building which, with its appliances, is called a “tipple.” It is here dumped into a screen, it runs from the screen into a car or boat, and is then ready to be hauled or floated to market.

If the opening of the mine is practically on the same level as the tipple the arrangements are very simple, as no extra motive power is required to get the cars to the dumping place. It is usual, however, to find the opening at a higher point than the tipple, since the latter must always be at the railroad track or on the bank of a river. It becomes necessary, therefore, in this case, to raise and lower the cars between the opening of the mine and the tipple. This is usually done by the inclined plane system, in which the loaded cars descending draw the light ones up. The same system is much used in the anthracite mines, and has already been explained.

The railroad tipple consists simply of a frame building from forty to sixty feet long, fifteen feet high, and from eighteen to thirty feet wide. This structure is set upon four or five plain timber bents, and its floor is usually twenty-seven feet higher than the top of the track rails which run beneath the outer end of it. A platform on this floor is so adjusted by a single shaft that, when a loaded car is pushed on it, it tips forward to an angle of about thirty degrees. The end gate of the wagon is then opened and the coal runs out on to the screen. This screen is simply a set of longitudinal iron bars inclined outwardly at distances apart of one and one half inches. All coal that passes over these bars is called “lump coal” and is run into a sheet-iron pan suspended from the scales platform, where it is weighed, and it is then dropped directly into a car standing on the track below it. The coal which passed through the first set of bars has, in the mean time, fallen on to a second screen with bars only three quarters of an inch apart. The coal that passes over these bars is called nut coal, and is also weighed and dropped into the cars, while the coal that passes through the bars is called “slack.” This is dropped into a shute, is carried by it into a car on the slack track, and is run thence to the dumping ground. When all three kinds of coal are loaded together it is called “run of mine,” while lump and nut coal together make “three quarter coal.” These tipples may, of course, be built with two sets of screens and platforms, and thus be made to do double work, and some of them are so built. Under the projecting end of the tipple there are usually four tracks; the first or outside one for box-cars, the next for lump-coal cars, the next for nut-coal cars, and the last for cars for slack. Four men operate a single railroad tipple; two dump and weigh the coal above, while the others trim and move the railroad cars on the track below. To this number a helper is often added, both above and below. Besides these men a boy is usually employed to rake the nut coal from the lower screening bars where it sticks and prevents the slack from passing through. Sometimes it takes two boys to do this work properly. Boys are also employed to push the slack with a scraper down the shutes into the car on the slack track when the elevation of the tipple above the rails is not sufficient to afford the necessary grade. Bars are being largely superseded now by revolving screens for separating slack from nut coal; they do the work far better, and make the employment of a raking boy unnecessary.

The river tipple is operated in much the same way as the railroad tipple, except that its apparatus must be so arranged as to accommodate itself to high or low water. The floor of the river tipple is usually placed from forty to fifty feet above low-water mark, and the weighing pan is held in position by a counter-weight, which may be raised or lowered at pleasure. A small stationary engine, or a hand windlass, draws the empty boat or barge into position under that end of the tipple which projects over the water. About twice as many men are required to operate a river tipple as are necessary to operate a railroad tipple, and while the railroad tipple costs but from two thousand to four thousand dollars the river tipple is built at an expense of from four thousand to ten thousand dollars. But even this latter figure is small when compared with the cost of an anthracite breaker, which may run anywhere from twenty thousand to one hundred thousand dollars.