Stoddart's Encyclopaedia Americana: A Dictionary of Arts, Sciences, and ...

near Pottsville, Pa., are nearly 1700 feet in depth-about 300 feet deep, which should be so arranged as much the deepest coal-shafts in America-and were put to dispense with further drilling for blasting until that down very quickly by means of the diamond drill. These depth had been reached. In the East shaft twentyshafts, two in number, as required by the Pennsylvania five holes were bored, and in the West shaft thirtymining law, are situated 700 feet apart. They are five. The bit adopted for the drill, which has since known as the East and the West shafts. The former come into general use, differed from the ordinary diais intended solely for raising coal: it is 16 feet long and mond bit in use up to that time in being concave 13 feet 10 inches wide outside of the timbers, and is instead of convex. It has circular grooves and small divided into two compartments. The West shaft is 25 cylindrical holes for the outlet and circulation of water, feet 8 inches long outside of the timbers, and is divided which is forced down through the centre of the boringinto three compartments, two of which are used for rods. The rods are made of gas-pipe 11⁄2 inches in diamhoisting coal, men, timber, rock, etc., and the other for eter. The water takes up the fine sand or pulverized an upcast for ventilation of the collieries. In sinking rock, carries it away from under the bit, and then rises these shafts it was determined to dispense with the use on the outside of the rods or pipes to the surface. of hand-labor in drilling the holes for blasting, and the When all the holes were bored to a depth of from diamond drill (see fig. 37) was chosen as the best instru- 250 to 300 feet, the machines, pumps, etc., were taken ment for the purpose, adopting a new plan; which was to the other shaft to bore the holes in it. During the to sink the shaft down to the solid rock in the usual way, boring in one shaft the rock was blasted and removed in and then by a number of diamond drills, each driven the other. The diameter of the holes was in all cases by its own steam-engine, to bore a series of holes 13 inches. On the completion of the boring they were

filled to the top with sand, and the work of blasting and removing the rock was begun.

The operation of blasting was conducted as follows: The miner, by means of a small pump, such as is used with ordinary boring-rods, removed the sand from nine holes to a depth of from 3 to 4 feet. Clay was then forced into each hole, so as to make a plug from 6 inches to 1 foot long, and on the top of this a cartridge of dualin was placed, and the holes were then tamped with clay. The cartridges were connected together by wires leading to a galvanic battery, and were all fired at once. The explosion was produced by a cap filled with fulminate of mercury. The result of the simultaneous discharge of these nine holes was the formation of a large cavity in the centre of the shaft to the depth of the bottom of the cartridges. The loosened rock was removed, and the remaining holes were charged and fired in the same way. The sides of the shaft preserved their proper form, and no hand-blasting was necessary for trimming them up. When all the holes around the shaft had been fired the miner began again with the nine central holes; and the work went on in this manner until the depth to which the holes had been bored was reached; the ma

chines were then set to work again and the holes bored from 250 to 300 feet deeper. The shaft was timbered as the work proceeded-yellow-pine timber 12 inches by 12 inches, placed at first skin to skin, and afterwards 2 feet apart, being used below the iron girders. The guides were of Carolina yellow pine, and were put in as required.

The drills were run day and night continuously, and the boring progressed at an average rate of 34 feet per day of twenty-four hours, including all delays, except those caused by stopping to blast away the rock. The East shaft was begun May 5, 1871, and finished Aug. 14, 1875; the West shaft was begun Sept. 1, 1871, and finished Feb. 14, 1876. (See Plates XII., XIII., XIV.)

The Wadesville shaft (Plate XV.) is located about onehalf a mile north of the Pottsville shafts, and cuts 661 feet of the same strata cut by them. The Mammoth coalbed has been worked by this shaft for some fifteen years, producing a large amount of coal. This shaft was located in 1864 by the Messrs. Sheafer, mining engineers, cutting the Mammoth bed at 619 feet from the surface. The report of the mine inspectors of Great Britain for 1882 says:

"The leading shaft at the Ashton Moss colliery, Ash

At 1

ton-under-Lyne, attained on the 5th of March, 1881, a depth of 897 yards, to the floor of the Great Mine bed. This is now apparently the deepest vertical mine in the kingdom, and it is still being sunk deeper, with the view of working a lower seam in conjunction with the Great Mine. The temperature of the strata, so far as yet proved, appears to be lower than the average. 871 yards it is stated as being, in rock, 78° Fahr., and at 897 yards, in coal, 86°. From information supplied by mining engineers and the sinkers, it appears that when about 54 yards in depth, the shaft being 18 feet in diameter gross for 16 feet when walled, a system of 2 circle-firing was tried. A circle of eight converging shots, 6 to 6 feet deep, 2 inches in diameter, equally distributed round a circle 12 to 14 feet in diameter, charged with about 23 pounds of dynamite, or 20 pounds between them, was first fired, and after firing, the stuff, about 40 tons, was filled out. A circle of twelve straightdown shots, also 6 to 6 feet deep, and equidistantly distributed round the circumference of the shaft, and charged with 2 pounds each, or 24 pounds between them, was then fired, which generally gave about 40 to 50 tons of stuff. The bottom and sides were squared off with small holes, in which powder was used. The 3 dynamite was put into the holes in 2-ounce cartridges, and the stemming was either water or sand. The firing was by electricity, the batteries being placed in a mouthing about 450 yards from the surface. Partly owing to the steepness of the dip of the strata, and partly to the vibration caused in the neighborhood, this system was given up. During fifteen days over which it extended 11 yards were sunk and 7 yards walled, as compared with 15 yards sunk and walled by the ordinary way with powder and tonite. To be successful it appears there should be two shafts sinking, and the work so arranged that the men could go from one pit to the other, one set of men being set to drilling and preparing shot-holes, whilst the other set are filling out the stuff from the firing." These are representative shafts in their respective countries.

The first shaft in the Southern coal-field of Pennsylvania was commenced by Alfred Lawton in 1845, on the west side of Mill Creek, not far south of Mine Hill, in the town of St. Clair. This shaft was sunk 72 feet; then a boring penetrated to a depth of 122 feet to the Primrose bed, when it was abandoned. In 1851, E. W. McGinnis continued the shaft down to the Primrose, and then bored to the Mammoth. He met with decided success, and immediately determined to sink the shaft (10'x18') to the Mammoth bed. The following table shows the strata cut and the distances of some of the layers from the surface: