Coal and the coal mines

by Homer Greene

Where the dip of the slope is less than thirty degrees the coal is brought to the surface in the car into which it was first loaded in the mine. At a greater angle than this the ordinary mine car is superseded by a car or carriage especially adapted to carrying coal up a steep incline.

Where there is no outcrop in the tract to be mined, and the coal lies below water level, the best mode of making an entrance to it is by shaft. In the Wyoming region, since the upper veins have been so generally mined out, nearly all the openings are by shaft. The location of the shaft at the surface should be such that when it is completed its foot shall be at the bottom, or nearly at the bottom, of the synclinal valley into which it is sunk. As will be more readily seen hereafter, this is necessary in order to carry the water of the mine to the foot of the shaft, to facilitate the transportation of coal under ground, and to get room to open up the greatest possible working area. The depth to which a shaft must be sunk depends on the seam to be reached, and on the district in which it is located. At Carbondale, in the northeasterly extremity of the Wyoming basin, the average depth to the conglomerate or bed of the lowest coal seam is 250 feet. From Scranton to Pittston it is from 500 to 600 feet. At Wilkes Barre it is 1,200 feet. It reaches its greatest average depth a mile northeast of Nanticoke, where it is from 1,500 to 1,600 feet.

This will be the limit of depth for shafts in the Wyoming region. At present the average depth is from 300 to 400 feet, and there are few that are more than 800 feet deep. The red-ash vein to which most of the shafts are now being sunk is, at Pittston in the middle of the general basin, from 450 to 650 feet below the surface. In the southern anthracite region the average depth of shafts is somewhat greater, the maximum depth being reached in the vicinity of Pottsville, where the Pottsville deep shafts are about 1,600 feet in depth.

In beginning to open a shaft a rectangular space is staked out on the ground from four to eight feet wider and longer than the proposed dimensions of the shaft; and the soil and loose stones are thrown out from this larger area until bed rock is reached, which is usually done, except in the river bottom lands, within a depth of twenty feet.

From this rock as a foundation a cribbing of solid timber, twelve inches square, is built up to the surface on the four sides of the opening to prevent the earth from caving in. Sometimes heavy walls of masonry are built up instead of the timber cribbing, and though the original cost is greater, the purpose is far better answered by the stone curbing. When this has been completed, sinking through the rock goes on by the ordinary process of blasting, plumb lines being hung at the corners of the shaft to keep the opening vertical.

An act of the Pennsylvania legislature, approved June 30, 1885, regulates the conduct of coal mining in the State so far as the safety of persons employed in and about the mines is concerned. Former acts are consolidated and revised in this, and new provisions are added. By virtue of this act both the anthracite and bituminous coal fields are divided into districts, each of which is placed in charge of an inspector, whose duty it is to see that the provisions of the law are carried out, and to make annual report to the Secretary of Internal Affairs of such facts and statistics as the law requires to be made. As there will be frequent occasion hereafter to refer to various provisions of this act of assembly, it will be mentioned simply as the act of 1885. The matter is brought up here in order that the rules relating to the sinking of shafts, as laid down in the act, may be referred to. These rules provide the manner in which the necessary structures at the mouth of the opening shall be erected, what precautions shall be taken to prevent material from falling into the pit, how the ascent and descent shall be made, that all blasts during the process of sinking shall be exploded by an electric battery, etc. All these rules have but one object, the safety of the workmen.

The horizontal dimensions of the modern shaft average about twelve feet in width by thirty feet in length. This space is divided crosswise, down the entire depth of the shaft, into compartments of which there are usually four. The first of these compartments is the pump way, a space devoted to the pipes, pump-rod, and other appliances connected with the pumping system. To this six feet in breadth is allowed. Then come, in succession, the two carriage ways, each of which may be seven feet wide, and, finally, the air passage through which the foul air is exhausted from the mine, and to which ten feet is appropriated. The partitions between these compartments are made of oak sticks six inches square, called buntons. The ends of the buntons are let into the rock sides of the shaft, and they are placed horizontally at a vertical distance from each other of about four feet. These bunton partitions are then closely boarded down the entire distance. The partition between the hoisting compartment and the airway is not only boarded up, but the boards are matched and are rabbeted together. It is necessary to make as nearly air-tight as possible this way for the passage of air, and where the edges of the boarding meet the rock sides of the shaft the irregularities are carefully filled in with brick and mortar.

Fastened to the buntons at each side of each hoisting compartment are continuous strips of hard wood, from four to six inches square, reaching from the top of the shaft to its bottom. These are the “guides.” To each side of the carriage, which raises and lowers men and materials, is fastened an iron shoe, shaped like a small rectangular box without top or ends. This shoe fits loosely on to the guide, slides up and down it, and serves to keep the carriage steady while it is ascending or descending. This invention is due to John Curr of Sheffield, England, who introduced it as early as 1798. The ordinary carriage consists of a wooden platform with vertical posts at the middle of the sides united by a cross-beam at the top, and all solidly built and thoroughly braced. The posts are just inside of the guides when the carriage is in place, and are kept parallel to them by the shoes already mentioned. To the middle of the cross-beam is attached the end of a wire cable, from which the carriage is suspended, and by which it is raised and lowered. On the floor of the platform, which is planked over, a track is built uniform with the track at the foot and head of the shaft, and continuous with it when the carriage is at rest at either place. The mine car is pushed on to the platform of the carriage and fastened there by a device which clings to the axle or blocks the wheels.