"RUN," WITH FAN VENTILATION.
In the plan presented on next page, we have given that which is known as the "run," but do not confine our description of the plan to this mode, since it is susceptible of much modification. The "run" can be used to advantage only when the seams are comparatively large, the dip 40° or over, and the top slate or rock firm and solid: when all these favorable conditions exist, it is the cheapest mode known of mining coal.
There are two or three methods in use. The one represented has "travelling-ways" or air-courses up each side of the breast, which is 30 feet wide. These are kept open for the passage of the miners and the passage of the air. They are secured by leaning timbers against the pillars, or by propping up the top coals and making a passage in the bottom portion of the seam.
The coal is blasted with powder from the face of the breast,—often in immense masses when the seam is large, as in the case of the Mammoth,—and falls into the body of the breast below, where it is broken into convenient sizes, and is then ready for the "loaders," who draw it as required into the cars, which stand on the railroad in the main gangway.
The coal when broken occupies double the space it does in the solid: therefore, as the miner progresses with his work, over one-half the coal must be drawn from the breast in order to give him room to work ; the remainder is left in the breast, to fill up the yawning gulf which otherwise would exist below him.
This method, known as the "run," is the cheapest and simplest known; but, a4 before said, it can be used only under certain conditions. If the dip is not steep enough, it will not run; or if the roof—top slate--is rotten and weak, it will fall among the coal and ruin its marketable qualities. Under such circumstances, the mode of mining adopted is similar to that described in plan 5, of which, in fact, this is nearly a copy. The coal is then thrown into the shutes, which, when not used for the purpose of sliding down the coal, are called travelling-ways. The space between the shutes, which is filled with coal when worked as runs, is in this plan open and dangerous, or partially filled with waste coal, falling slates, and bulwarks, or "batteries" of timber.
"in both modes the air-courses or passage-ways are often carried through the middle of the pillars, and headings driven occasionally, as required, from one breast to the other.
In the plan presented, the air circulates up one side of the breast and down the other. It would perhaps be equally available to take it up one breast and down the other, or to carry it along the faces from one to the other. In this last mode, the air ascends the inside breast, passes through "headings" in tit% pillars to the succeeding outside breasts, and descends the last outside one to the return air-course f.
The inlet air-course e, below the gangway d, may be dispensed with, and the air taken through the gangway d to a point near its face, and then passed up the inside shute, as shown in the engraving, to the inside breast i. It may then circulate up and down the breasts alternately, or traverse the face of each breast, and descend the out side one to the return air-course f. This is ventilated by a fan, c, near the top of the upcast slope c, and may be supplied with more air than is required for ventilation: therefore there is a surplus, and the shutes may be ventilated by " escapes" when de sired, provided the mode of "sweeping" the face of the works is adopted. This plan is perhaps the best in use, since the distance to be traversed is less than in other cases; but it is still liable to some of the serious objections advanced against nearly similar modes in considering the plans presented on page 416, while the objections to the waste of coal in pillars remain unchanged.
Having thus briefly described the modes of mining and ventilation generally in use in the anthracite coal-fields, and to a great extent, also, in most of our bituminous fields, we now venture to present a modification of the English systems, as adaptable to the peculiar anthracite formations; and if we succeed in presenting them clearly and com prehensively, we have no doubt of a favorable result, since the improvement must be apparent to the mind of every practical miner.