in chamber B adjoining are probably making the first slice at the top of the chamber. As soon as slice 8 is finished in chamber A, slice 9 is made, completing the work in the chamber, and the shaking chute is removed. Then the stump of the pillar at 10 is recovered; as this stump is adjacent to the rock hole, use of the shaking chute for transporting the coal from it is unnecessary.

This system of mining permits a recovery of nearly 100 per cent. Were the roof not as strong as it is, part of slices 4 and 7 might be lost, but, as a matter of fact, this coal can be recovered without loss.

Construction of chutes.—The shaking chutes are homemade of 11gauge steel plate. They are 20 inches wide, semicircular in section, and made in lengths of 8 feet. A connecting strip of 11-gauge metal about 6 inches wide is riveted to one end of each length; four holes are punched in it, and corresponding holes are punched in the opposite end of each length. All that has to be done in connecting two lengths is to overlap them, so that the holes in the joint of one length will coincide with the holes in the other end of the second length, and then bolt or rivet the lengths together. For the chute to make a turn extra holes at the desired angle are punched in the unriveted end of a length. Of course, if a turn is sharp a number of lengths, properly punched, are required. The shaking chutes are supported by props, that is, two props placed about 3 feet apart. An iron bar or piece of pipe is placed across these props and across the chute as well; it is held in place by very heavy spikes. Steel hooks fit over the iron bar and through holes in the connecting piece of each section of the conveyor. A very necessary detail in setting up a chute is to see that the hangers are vertical and not at an angle when the chute is stationary, for if one hanger runs uphill and the other downhill they form a cross brace that prevents the chute from moving.

On the first or second lengths of the chute next to the rock hole an eye is riveted to the under side and a rope is fastened through it. This rope passes over a sheave and goes to the engine that operates the chute. The engine may be virtually any type using compressed air and is fitted up at the company shops to be gear driven. A steel disk to which is bolted a tee is attached to the main shaft, and the rope is fastened to the ends of this tee. As the disk revolves the rope is pulied backward and forward.

If more than one shaking chute is used, it is very desirable for the other rope to be attached to the opposite end of the tee on the disk, thus equalizing and balancing the strain on the engine. As many as eight shaking chutes, four on each side, have been operated by one engine in this bed. The main rope attached to the engine is endless, and the shaker ropes are fastened to the main rope with

When this report was written, the company was making arrangements to run six shaking chutes from one engine, and Figure 33 shows the proposed method of operating. This sketch also shows the arrangement of the ropes and how they are balanced so that the load on the engine will be equalized. Any shaking chute can be stopped at any time by disconnecting its drive rope from the endless rope.

Operating data.—The miners are paid for handling the shaking chute and are paid by the car for all the coal they load. They receive 70 cents for taking each section from the gangway into the

Shaking chutes

Sheave

Sheave

Drive

US

Endless rope
Connecting ropes

Figcrh 33.—General type of connections and layout used with endless-rope drive systems for shaking chutes

chamber and 50 cents for placing the section on the chute. When the work is finished, they are paid 70 cents for removing each section of the shaking chute and delivering it to the top of the rock hole.

SHAKING-CHUTE MINING IN ELEVEN-FOOT BED

The company is using a similar type of shaking chute with satisfactory results in the Eleven-Foot bed, which has the following cross section:

Table 35.—Section of Eleven-Foot bed, near Pringle Township

In the Top Ross or Monkey bed each miner averages a little more than a car a day, whereas in the Eleven-Foot bed, where the coal is a USE OF INDIVIDUAL-DRIVE SHAKING CHUTE UNDER DIFFERENT

CONDITIONS

Anthracite can not be mined by an exact and uniform procedure; methods must be changed to meet different conditions. In some mines methods may have to be modified from room to room. Therefore, to work successfully in the anthracite region, a mechanical device must be as flexible as possible.

At the time this bulletin was written experiments seemed to indicate that there is only one limit in this country to the application of shaking-chute mining under all the conditions found in the anthracite region; that limit is the pitch. As yet shaking chutes have not been devised that can move coal up a grade successfully or on a level on a large scale. They can move coal on a level, but the capacity becomes so small that there is no advantage in using them. Shaking chutes are obviously unnecessary when the pitch of the bed is so steep that the coal will slide of its own accord, without mechanical aid.

SHAKING-CHUTE MINING AT MINES OF JEDDO-HIGHLAND COAL CO.

Probably the greatest variety of uses of shaking chutes in the anthracite region is to be found in the mines of the Jeddo-Highland Coal Co., Jeddo, Pa., in beds that range in thickness from 5 feet to as low as 20 inches. The pitches vary from flat to an angle at which the coal slides of its own accord. The coal company is using these chutes both in ordinary first mining and in second mining with great success.

To show how conditions change in anthracite mining, attention is called to one of the gangways at the Highland No. 5 mine of the Jeddo-Highland Coal Co. Here the pitch normally is between 3 and 15 per cent, but two rolls cut across this gangway, and unusual conditions must be met.

As an example, take a room which has been driven to its limit. Near the upper end of the room the pitch is low; farther down it increases until the coal moves of its own accord; still farther down it flattens so much that the coal comes to a standstill; then the bed commences to pitch again, and again flattens out. To bring the coal from the face of the room to the gangway for loading into mine cars, the company installed three sets of shaking chutes. The last chute moved the coal from the face to the steep pitching section. There the coal slid down to the bottom; then it was carried by another shaking chute over the comparatively level space and was discharged onto the second steep pitching place in the chamber, sliding down that to the third and bottom level space, over which it was carried by the third shaking chute which discharged into the mine car. Only two chambers away from this a shaking chute could be used from the gangway to the end of the chamber, showing what abrupt changes in conditions have to be combated.

Experimental work.—This company noted some interesting factors in its experimental work. At the end of a long shaking chute on a medium pitch was another chute discharging into it. The first chute was driven by a direct-connected motor and the second by a rope from the first chute. Some trouble resulted, and it was decided to make the two chutes continuous and use the same drive. When the chutes were connected, the proper shaking motion could not be obtained on the last section at first, but removal of the engine to a point above the elbow connecting the two chutes remedied the trouble and gave a satisfactory motion. In other words, the chutes were actually shortened by placing the drive halfway between the ends, reducing the lost play and imparting a longer stroke.

This experience shows that if there is a sharp bend in a chute and the chute extends for any distance beyond it the best results are obtained by placing the engine above the bend. However, this precaution is not necessary if the chute does not extend far beyond the bend.

The methods of robbing illustrate this point with particular apt-' ness. It has proved advisable to bend the chute to reduce to a minimum the distance the coal has to be handled by shovel. The upper end of the chute is therefore continually kept near the loading point, and in consequence numerous bends are made in the chute. The chute itself does not extend far beyond the bends, and under these circumstances attaching the engine to the chutes below the point of bend seems to be successful. This company has been able to operate successfully chutes making a complete S bend.

Remedying faults.—Some of the worst faults of shaking chutes probably result from the method of connecting the sections. At present most of the companies use a butt joint; one section is riveted to a piece of flat scrap iron to which the other section is bolted. As the bolts usually are not very tight they shear and enlarge the holes in the sheet steel; as these holes become enlarged the sections slip at the points where they are joined and the length of stroke is shortened in consequence. If there are many sections in a chute, this small amount of lost motion at the end of each section is multiplied by the number of sections and it is very possible for all shaking motion to be lost in a long chute.

A - flange joint would be a much better type of construction. The angle irons would then be riveted to each end of the sections and so drilled that when the sections are placed together the holes will coincide and will permit the sections being bolted together tightly, obviating the jar on the plates and reducing lost motion to a

Some of the companies have successfully introduced S hooks and chain for hanging the chutes. Where a hanger of any fixed length is used, a number of different lengths have to be kept on hand or else the chute has undulations which correspond to those of the bed; but if the chutes hang from a chain, which is shortened or lengthened by hanging the different links in the S hook, the chute can be kept at an even grade and a more regular flow of coal obtained.

Another important feature in the introduction of the shaking chutes is the method of loading the mine cars. It is not necessary to have a loader on the gangway to trim the cars, as the men themselves are soon able to determine the amount of coal in the mine cars, although they may be 300 feet away. When a car is nearly full, one of the men at the face can go down to the gangway, trim the car, and shift another one in loading position. Very little time is lost, and a decided saving results.

Disadvantages of shaking chutes.—One objection to the shaking chutes in places where the pitch is fairly steep or the coal is thin is the difficulty of taking supplies from the gangway to the working face. The shaking chute usually occupies the center of the working place, and gob is thrown to either side. The shaking chute is also kept as straight as possible and many working places are crooked; therefore the men traveling from the gangway to the face have to cross over the shaking chute a number of times. The writer has crossed a chute as many as five times going up a room. Much of this inconvenience could be eliminated if each foreman saw to it that his place was driven reasonably straight and that the gob was kept entirely on one side of the chute; but even then it would not be easy to carry props or to take up 8-foot sections of the chute in very low coal. Use of niggerheads on the driving machinery may largely obviate this difficulty. A light %-inch steel rope can be used in each room, a jack screw and snatch block placed at the face of the room, and the rope run up the shaking chute and down on the one side of the timbers to the face; dogs can then be driven into the timber, attached to the rope, the rope passed around the niggerhead, and the engine started. The rope will then pull the timber or supplies to the face. It might be advisable to use a tail rope to drag back the rope to its starting point. In order to take up sections of the chute, the same outfit can be used, but instead of dragging the section of the chute up in the chute, it would have to be dragged along the bottom of the working place, increasing the advisability of keeping the room clean on one side and as straight as possible.

The Jeddo-Highland Coal Co. is using a few compressed-air cylinders to drive shaking chutes, but the best results seem to be obtained