by driving a manway up between each two breasts to take the place of the juggler manways, and the amount of coal so saved does not warrant the expense of this additional narrow work.

When the bed is thin, the roof poor, and the dip less than forty degrees, breasts are sometimes opened by a single shute eight or ten yards long, above which the working is opened out to the full width. The coal-way is made up the center of the breast and is kept open by two rows of props on each side, the rows being two or three feet apart and the props from four to eight feet apart. A brattice placed on one of these rows converts one side of the breast into an airway and the space between the other row is used as a travelling-way. The props are of six or eight inch round timber. When this plan is used the roof is so thoroughly propped that accidents from roof-falls are rare. The coal is run as mined, and the gob is piled against the rib on each side of the breast.

When the amount of refuse (gob) is large, or when the bed is gaseous, the breasts are opened by two shutes,see Fig. 2, Atlas Sheet No. XXII,-which are extended up along the rib to within a few feet of the working face, either by building a juggler manway or by planking carried on upright props. The illustration shows a breast opened by this plan on a dip too steep to enable the miners to keep up to the face; and the platform built on props, on which they stand to mine the coal. On dips of less than thirtyfive or forty degrees these platforms are not necessary, and in beds exceeding ten or twelve feet in thickness they cannot be built; hence this method of working is applicable-1. To beds dipping less than thirty-five or forty degrees; and 2. To thin beds on steep dips.

The coal is separated from the refuse on the platformthe coal sent down the manway shutes, and the gob thrown in the center of the breast behind the platform. Breasts worked by this method are spoken of as being worked "on batteries." A considerable amount of gob is purposely thrown on top of the jugglers and manway planking, and a certain quantity of coal is kept on the platform to deaden

the blow from falling coal, or roof-falls of slate, that might otherwise crush in the jugglers or props and close the airway, or by breaking the platform would set free a large quantity of coal that would fall and become mixed with the gob below.

The coal is run down the shutes and is loaded into the car over an apron projecting into the gangway.

In the illustration the shutes are timbered, but it will of course be understood that timbering is not erected unless the character of the coal or roof demands it.

When the dip is steep, forty-five or fifty degrees or more, the coal falls down these shutes with great violence, tumbling around from side to side and in collision with the roof and floor alternately, and a very large percentage of fine coal (coal-dirt, dirt) is thus made. In the softer, and also in some of the more brittle coals, this is an objection almost fatal to this method of working.

When the amount of refuse is sufficient to fill the center of the breast, the miners can work without the platforms as they can then stand on the gob,-under such circumstances this method can be used in thick beds on steep angles of dip.

In addition to these methods of opening breasts on moderate dips, there are several other plans differing from them in minor details, and which will not be separately described here. In some localities the methods especially applicable to thick beds and steep dips have been modified and adapted to thin bed mining and to more gentle pitches, but these adaptations do not require any special discussion.

In thick bed workings on steep pitches, it is impossible for the miner to keep up to the working face,-in other words, he has nothing to stand on,—and it is therefore necessary either to leave the loose coal in the breast or to erect some artificial support. When the bed is comparatively thin the method of working "on batteries" can be adopted, but if the pitch is very steep such a large amount of dirt (fine coal) is made by the coal falling down the manway shutes, that the adoption of this method is not advisable.

As already indicated, the amount of gob may in some

cases be sufficient to fill the breast and keep the miner up to the face, but the beds now worked seldom contain enough refuse to fill the breasts on steep dips.

When the coal is to be left in the breast to support the miner an entirely different system of opening and working is adopted. It then becomes necessary to provide means for the withdrawal of the coal left in the breast, for the removal of the surplus coal, (the loose coal occupying fifty to ninety per cent. more space than coal in the solid), for ventilation, for the conveyance of supplies and for ingress and egress of the miner.

The surplus coal may be drawn out at the bottom through the opening in the battery, but it is frequently sent down the manways, which are also used for ventilation and as traveling-ways. These manways are often called manwayshutes or juggler manways, this latter name being given to them because they are built of "jugglers" or inclined props, faced by two inch plank. They are made as nearly air-tight as possible, especially the one conveying air to the face.

A section at the top of Page plate No. 18 shows how these manways are carried up along each side of the breast.

The jugglers are notched into the pillar coal and also into the floor to hold them securely in place, and are set at intervals of from four to six feet.

The surplus coal may, as already indicated, be drawn out through the battery hole; but, if the roof of the bed is poor, the movement of coal through the breast may cause it to fall and mix with the coal; if the floor is soft, the jugglers (being stepped down into the floor) may be unseated and the manways closed or the ventilation impaired. For these reasons the surplus coal is best sent down the manways and the loose coal in the breast allowed to lie entirely undisturbed until the breast is driven to the limit.

When the surplus coal is to be drawn out through the battery, the plan of opening by one (central) shute is preferred, because the movement then takes place principally in the coal lying near the center of the breast, and the risk