MINING FOB COAL 



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are generally let into each other about an inch, instead of being half-checked. Fiq, 

 14-92 is a double shaft: A, the pump pit ; B, the pit for raising coal. Fig. 1493 ig a 

 triple shaft ; in which A is the pump compartment ; B and c are coal pits. Fig, 1494 

 is a quadrant shaft : A, the pump pit ; B, pit for ventilation or upcast for the smoke 

 c and D, pits for raising coals. 



Whenever the shaft is sunk so low that the engine is needed to remove the water, 

 the first set of pumps may be let down, by the method represented 'mfig. 1496 ; where 

 A is the pump ; a a, strong ears through which pass the iron rods con- , , 0ft 

 nected with the spears bb; c c, are the lashings ; d, the hoggar pump ; 

 e, the hoggar ; //> the tackles ; g g, the single pulleys ; and , the pump- 

 spears. By this mechanical arrangement the pumps are sunk in the most 

 gradual manner, and of their own accord, so to speak, as the pit descends. 

 To the arms of the capstans, sledges are fastened with ropes or chains ; 

 the sledges are loaded with weights, as counterpoises to the weight of the 

 column of pumps, and when additional pumps are joined in, more weight 

 is laid on the sledges. As the sinking set of pumps is constantly descend- 

 ing, and the point for the delivery of the water above always varying, a 

 pipe, of equal diameter with the pumps, and about 1 1 feet long, but 

 much lighter in metal, is attached to e, and is terminated by a hoso of 

 leather, of sufficient length to reach the cistern where the water is de- 

 livered. This is called the hoggar-pipe. In sinking, a vast quantity of 

 air enters with the water, at every stroke of the engine ; and therefore j jjt\\i 

 the lifting stroke should be very slow, and a momentary stop should 

 take place before the returning stroke, to suffer all the air to escape. 

 As the working barrels are generally 9 or 10 feet long, and the lull 

 stroke of the engine from 7 to 8 feet, when at regular work, it is custom- 

 ary to diminish the length of stroke, in sinking, to about 6 feet ; because, 

 while the pumps are constantly getting lower, the bucket in the working 

 barrel has its working range progressively higher. 



Another method of suspending the p\:mps in the sinking shaft, in tho 

 place of the ropes and blocks, is by two powerful iron screws about 

 15 feet in length, which are supported at the top of the shaft by strong 

 beams of timber. As the shaft is sunk, the pumps are lowered by the 

 screws ; when lowered sufficient for a pump 9 feet in length,, the pumps are securely 

 fastened, while the screws are detached and screwed up ready for again lowering the 

 pumps as the shaft is sunk. 



The water obtained in sinking through the successive strata is, in ordinary cases, 

 conducted down the walls of the shaft ; and if the strata are compact, a spiral groove 

 is cut down the sides of the shaft, and when it can hold no more, the water is drawn 

 off in a spout to the nearest pump-cistern ; or a perpendicular groove is cut in the 

 side of the shaft, and a square box-pipe either sunk in it, flush with the sides of the 

 pit, or it is covered with deal boards well fitted over the cavity. Similar spiral rings 

 are formed in succession downwards, which collect the trickling streams, and conduct 

 them into the nearest cistern ; or rings made of wood or cast iron, are inserted flush 

 with the sides of the pipe ; and the water is led from one ring to another, through 

 perpendicular pipes, itntil the undermost ring is full, when it delivers its waters into 

 the nearest pump-cistern. Keeping the shaft dry is very important to the comfort of 

 the miners, and the durability of the work. 



When an engine shaft happens to pass through a great many beds of coal, a gallery 

 a few yards long is sometimes driven into each coal-seam, and a bore then put down 

 from one coal-seam to another, so that the water of each may pass down through these 

 bores to the pump-cisterns. The water is more frequently taken down the shaft in 

 pipes to the nearest cistern. 



While a deep pit is sinking, a register is kept of every part of the excavations, and 

 each feeder of water is measured daily, to ascertain its rate of discharge, and whether 

 it increases or abates. The mode of measurement is by noting the time, with a 

 seconds watch, in which a cistern of 40 or 50 gallons gets filled. There are modes 

 of keeping back or stopping up these feeders, by plank tubbing, iron tubbing, and 

 by oak cribs. Let Jig. 1497 represent the sinking of a shaft through a variety of 

 strata, having a top cover of sand, with much water resting on the rock summit. Each 

 plane of the coal-measure rises in a certain direction till it meets the alluvial cover. 

 Hence the pressure of the water at the bottom of the tubbing that rests on the summit 

 of the rock is as the depth of water in the superficial alluvium ; and if a stratum a 

 affords a. great body of water, while the superjacent stratum b, and the subjacent c, are 

 impervious to*Tater ; if the porous bed a be 12 feet thick, while no water occurs in 

 the strata passed through from the rock-head, until the depth (supposed to be 50 

 fathoms from-tho surface of the water in the cover); in this case, the tubbing or 



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