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.