Table 32.—Section of Seven Foot bed near Minersville, Pa.

Mining methods.—The map (fig. 29) gives the grades on which the scraper is working. The pitch reverses at the point where the roll is shown. Here it proved advisable to take down roof and construct a bridge across the roll, so that the scraper could be handled more readily.

FlGCSB 29.—rart of workings in Seven Foot bed, where scraper Is used, at Pine Hill colliery of Pine Hill Coal Co.

When the mine was visited rooms A and B were being mined. They had been driven to their full length, and the pillars were being robbed. As Figure 29 shows, the coal pitches more steeply to the right of the rooms, and a new room was being driven to the right up the pitch. When this room reached the gangway above, the pillar on

When the pillar was drawn back as far as the old room, a new room, shown by the dotted lines, was driven up the pitch; the pillar on the left was then drawn back in the same manner. As soon as the first new room was driven up, another room was turned to the right from the next room. When the second room reached room A, its pillar on the left would be drawn back. Scrapers do not have to be used in driving the new room to the right up the pitch, as the pitch is steep enough for the coal to run. After running down the new place to the old rooms, the coal is picked up by the scraper, taken down the room to the main gangway, and loaded into the mine cars.

In this type of mining, one Strange scraper can load as many as 20 cars a day with comparative ease and will average about 18 cars.

J Hoist

Figure 30.—Typical layout for Strange scraper

At this mine there is a miner and a miner's laborer in each place, a loader on the gangway, a hoisting engineer tending the hoist, and a driver who takes the mine cars from the room chute and dumps them into the rock hole. The coal is loaded into other mine cars in the Buck Mountain bed, which lies below. It is customary to have one scraper outfit for every three places, making necessary a total of nine men in all at work and giving an average production of two cars a day for each man. Actually only eight men should be considered as a shift, for one man is used as a driver to haul the coal to a rock hole. In ordinary mining the services of this man would not be required, therefore his pay should be charged against haulage instead of scraper mining and the average number of cars loaded by each man would be 2.25.

Figure 30 shows a typical layout for a Strange scraper outfit. A separate scraper is provided for each room and when not in use scrapers and is pulled out of the room by the hoisting engine after the miner has loosened it at the face. Then the set is taken to the adjoining room and pulled to the face by the men.

Arrangement of pulleys.—Figure 31 shows the arrangement of the pulleys at the face in starting the scraper. When the loading out of a full room is begun, a long pipe prop having a pulley (through which the tail rope is run) attached to its end is thrown on top of the coal in a corner. The other end of the pipe prop is held against the roof by a jack prop. Between the pipe and the jack is a swivel. A second pulley, through which the tail rope leads to the winch, is secured to the roof at the edge of the pile at the opposite rib. This setting requires only a few minutes, and the ropes are free of the coal. The

scraper cleans a path along the rib to the face, then the pole is taken down and set up in the next room.

When the scraper has cleaned a path to the face, a jack prop is set up, one of the two chains fastened to a snatch block is attached to this prop, and operation of the scraper is started. The jack should be set so that the block pulls to the edge of the coal and the scraper can slice off the edge of the pile. Meanwhile the second chain of the snatch block is attached to a second prop, which is set up at the desired distance along the face. When the block is to be shifted, the first prop is relieved, and the block moves over to pull on the second prop. The first prop is then set again, and the entire face is thus cleared step by step. The last pull can be across the face, if complete cleaning of the face is desired. Movement of the scraper is con

SHAKING CHUTES
SHAKING-CHUTE MINING IN A THIRTY-INCH BED

Haulage from the working face to the gangways is probably the most important problem in mining thin beds of coal. It is seldom difficult to get men to mine 2-foot and even thinner beds of coal if a suitable method of moving the coal from the face of the working place can be provided; in fact, a certain class of miners prefer working in low coal to working in thick coal.

Thus the problem becomes one of cost to the company. Coal can be removed, but can it be moved economically? Roadways can be driven to the face of each working place and the mine cars taken in, but when a bed of coal is only about 2 feet thick 3 to 4 feet or more of rock has to be brushed from the roof or lifted from the bottom to give clearance, and the cost of such work can soon become prohibitive. Therefore, any system of mining that obviates the removal of rock from the top or the bottom of the room tends to increase economy. If the roadways in the mines had a long useful life, removal of rock probably would be cheapest in the end, but as soon as coal adjacent to them is removed the roadways have no value and the investment they represent becomes worthless.

Numerous devices for removing the coal from the working face, such as portable conveyors, scrapers, and shaking chutes, have been tried. The East Boston Coal Co., in Pringle Township, Luzerne County, Pa., has developed a system of shaking-chute mining in thin beds of coal that probably differs a little from any other used in the anthracite region.

Bed mined.—The East Boston Coal Co. is mining the Top Ross bed, the Ross split, or the Monkey bed, as it is variously called. At the highest point visited by the writer this bed has the section shown in Table 34.

Table 34.—Section of Top Ross bed

Immediately under the Top Ross and separated from it by rock 6 to 12 feet thick is the Ross bed. The Ross bed itself is about 14 feet thick, and first mining has been completed. All of the workings in the Ross have been silted and have squeezed. Where squeezes have torn of the Top Ross and left that bed hanging, so that it can be shot down easily. In places where it has not squeezed the Top Ross bed is, of course, intact. Second mining is now in progress in the Ross bed in those sections that underlie the areas first and second mined in the Top Ross.

Mining methods.—In order to mine the Top Ross, rock holes or rock chutes on 100-foot centers are made from the gangways in the Ross bed. As soon as the holes reach the coal the miner in each drives a doghole to connect with the adjoining rock hole and thus establishes ventilation. As soon as ventilation is established a room 24 feet wide, whose outside rib is alongside the outside rib of the rock hole, is driven up the pitch of the coal, approximately 8°. When this room is about 20 feet in, a shaking chute is placed in it and is kept near the outside rib. As the room is advanced the shaking chute is extended, and the gob is placed along the side.

The room continues until it reaches the gangway or the rock hole above, then a slice is taken off the outside pillar, as indicated by 1, Figure 32. The pillar remaining is about 38 feet wide, for half of it was removed when the rock hole outside of the one under discussion was worked. The shaking chute is turned into the working place, and all the coal in this diagonal section is removed, then slice 2 is drawn back to the cross heading, followed by slices 3 and ^ (bringing the pillar back to the first cross heading); then slice 5 is taken, leaving a stump of coal. Slice 6 is then completed. The shaking chute is always turned so that it is handy for the men to load into. When slice 6 is completed, slice 7 is taken on the inside of the gob in chamber A, then slice 8 is brought back to the cross