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The system of ventilation adopted, and the amount of gas given off by the coal, govern the size of the cross-headings. They are often driven as small as possible, but when the gas is troublesome, and the air current is coursed through a group of several breasts, they are made very large. About four feet by five or six is as small as they are commonly driven, and a size of six by eight feet, is about the maximum, except in very gaseous workings.

When the bed is less than ten (or twelve) feet thick, it is supported by propping (when necessary), in thicker seams the cost of long heavy props and the time and labor spent in setting them are so great an expense that no attempt is made to support the roof.

Two methods of working flat breasts in thick seams are in use. In the first method the breast is opened out and driven to the limit in the lower bench of coal, say to a height of from five to eight or ten feet, the top, if necessary, being supported by props, and the top benches are blown down afterwards, beginning at the face and working back; or when the roof is good and there is no danger of a roof fall closing the working, the upper benches may be worked in the opposite direction, beginning at the wagon-way and driving out towards the limit.

In the second method the working is opened at once to the full height of the seam, and so driven to the limit of working.

When the roof is very poor and the coal itself is hard enough to make a fair roof, or contains a parting of slate that will make a good roof to the lower opening, the first method is by far the better plan of working, and if the upper benches are worked back towards the outlet the danger of closure from roof-falls is avoided.

It frequently happens that the coal is of such a character that, after being undermined by the removal of its lower bench, the upper benches need only a few shots to start them and then fall in large masses that must be broken up with powder.

When the full height of the bed is worked at one operation, the miner usually first underholes the top by mining

the lower bench to a depth of a few yards, varying with the thickness of the bed, and then blows down the upper benches by a few shots located near the top. In very soft coal the top benches often begin to fall as soon as they are undermined a distance of two or three yards.

The miner reaches the top benches either by standing on the fallen coal, by a rude timber staging or by ladders.

2. Buggy breasts.

When the dip of the coal exceeds six or seven degrees, the grade is too great to take the mine cars into the working places*, and when the dip is less than twelve or fifteen degrees, as the coal will not slide down to the outlet, it is transported from the face to the gangway in small mine cars or wagons known as "buggies," and the coal is said to be "buggied," the breasts being known as "buggy breasts."

Buggies vary in capacity from half a ton to a ton, and as they must be pushed up to the face on a track that has quite a considerable grade, they are made as light as is consistent with proper strength. They are provided with a door at the rear end, through which the coal is dumped on the platform or into the loading shute, and run on a track laid through the center of the breast.

On steep pitches wooden rails are preferred to iron, because the friction between the wheels and a wooden tramroad is greater than when iron rails are used, and the buggy is more thoroughly under the control of the miner, but on more gentle pitches iron rails are used. The guage is commonly from two feet and six inches to three feet.

A buggy breast as opened in a bed nine or ten feet thick is shown by Fig. 4, Atlas Sheet No. XXII, in which the buggy is run out on a staging at the lower end of the breast, so that the loading platform and shute may be made to hold a considerable quantity of coal.

*Wagon breasts are occasionally opened in coal steeper than this, but the work of pulling the mine car up to the face is very laborious, especially when a large heavy car is used, and this practice is adopted by very few mining engineers. Wagon breasts have been opened on dips so great that a block and tackle were necessary to draw the car up to the face, but this practice seems to me to partake of the nature of a "lazy man's load."

When the bed is very thick the breast or shute may be opened near the top of the gangway and driven in horizontally until the floor is reached; by opening out in the top benches, sufficient room may be obtained to load the coal directly into the mine car over an apron projecting into the gangway. The expense of shoveling the coal from the platform into the mine car is saved by this plan; but it can seldom be adopted, and is objectionable from the fact that a large amount of bottom coal is left at the lower end of the breast that must be mined after the breast is exhausted, and if the bed contains much refuse this coal will be covered by a large amount of gob that must be removed before the coal can be taken up.

Buggy breasts are opened with a single shute, and in other respects are worked in the same way as wagon breasts, the coal being cleaned in the breast and the gob thrown on one side of the road bed.

For mining coal from buggy and wagon breasts the miner is paid a certain sum for each mine car of properly cleaned coal sent from the mine; the price varies at different collieries according to the size of the car, the thickness and character of the coal, and the amount of refuse contained in the bed.

Fig. 4, Atlas Sheet No. XXII, shows a buggy breast with the shute opened directly from the gangway, and a mine car standing in front of the platform in position for loading. A better plan is to widen out the mouth of the shute at the gangway and thus obtain room for a short siding, (just long enough to hold one mine car,) on which the car may stand while being loaded or until the miner is ready to load it. By this plan the gangway is kept open as a haulage road; when the other method is employed it is always obstructed by cars being loaded. In pitching breasts the cars are quickly loaded from a shute and the obstruction is only momentary; but when the coal is shovelled into the car by hand, the loading occupies from fifteen minutes to three quarters of an hour, in addition to any delay occasioned by the miners not being ready to load. On gangways used as haulage roads for a considerable number of breasts, the cost of the

short sidings is small, in comparison with the time lost by frequent blockades on the gangway.

Such an arrangement is also resorted to in fiery mines, when for the purpose of more thorough ventilation, it is necessary to cut off all communication between the breast and the gangway, by laying the siding into the shute a sufficient distance to admit the mine wagon, and closing the shute by a door, which is opened only when a loaded car is taken out or an empty one taken in to be loaded.

3. Pitching or Shute-breasts.

In steep-pitching breasts the coal slides down through the breast to the shute, and through the shute into the wagon, by gravity. When the dip is from twelve or fifteen up to twenty-five or thirty degrees, sheet iron is laid on the floor of the breast and also in the shute to facilitate the movement of the coal, but on a dip of less than eighteen or twenty degrees the coal will not move freely even on sheet iron, and must be pushed down by the miner.

When the inclination is less than twenty-five or thirty degrees the workings may be opened and worked like buggy breasts, with one shute which ends in an apron projecting into the gangway high enough to allow a mine car to pass beneath it; but the coal instead of being buggied to the shute, slides down over sheet iron laid on the floor of the breast. When this method is employed the gob is thrown on either side of the breast out of the way of the sliding coal. If the pillars are to be robbed by skipping one rib only, it is well to keep most of the gob on one side of the breast.

When the roof is good and the breasts are driven ten or twelve yards wide, they are frequently opened with two shutes, but unless this is necessitated by the method of ventilation, no great advantage is to be derived from it and the cost of opening is considerably greater.

When the dip exceeds thirty degrees the coal will slide on the floor of the breast without the assistance of sheetiron, but as the gob will also slide down the pitch and run out with the coal, a different method of working is adopted. (See Fig. 3, Atlas Sheet No. XXII.)

The breast is opened by two shutes driven in from eight to ten yards and the working is then opened out to its full width. Each shute is entirely closed by a plank partition located a few feet from the gangway with an opening in it through which to draw the coal, and which the miners use in passing up into the breast. This partition is called a "battery." When the coal is drawn from the breast through a log battery, the shute battery is known as a “check battery." Check batteries are used both to check the flow of coal and to confine the air current to its proper course through the breasts. As the breast is driven up the pitch, the gob is thrown in the center and the coal is thrown down the shute to be loaded in mine cars standing on the gangway below. A manway used also as a shute for the coal, is carried up on each side of the breast to confine the gob, and prevent it from running out with the coal.

In thin workings these shutes may be built of upright props (at right angles to the dip) or they may be inclined "juggler" fashion, but in thick seams the juggler* manway is nearly always adopted. They are faced inside by twoinch plank and are tight enough to make fairly good airways.

This plan of working is not applicable to seams dipping more than thirty-eight or forty degrees, as the miners then have no means of keeping up to the face, (i. e., the slope is too steep to stand on without some artificial means of support,) unless the bed contains such a large amount of refuse that the top of the gob is always within a few feet of the working face.

In its passage down the manway shutes the coal is subjected to much attrition and the waste from fine coal is largely increased. This waste might be greatly reduced if the manways could be kept full of coal and from time to time drawn out at the bottom, as the whole mass would then settle slowly down with comparatively little breakage; but as these passages are needed not only for use as manways but also as airways, this can only be accomplished

*The mode of building a “juggler" manway will be described further on.

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