Minutes of Proceedings of the Institution of Civil Engineers Volume 80, PT. 2
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1885 edition. Excerpt: ...5 feet apart, generally about 30 inches below the required depth, a cast-iron shell weighing about 100 lbs. being used to steady the lower end of the drill when entering the rook. This shell was about a foot in height, 15 inches in diameter at the base, standing on three pivots or legs, about 3 inches long, convex on the top, through the centre of which a hole passed vertically admitting of the free working of the drill; ropes were attached leading to the scow, by which it was lowered and raised. When the drilling of each hole was completed, the sediment was removed by forcing water through a tube reaching from the deck to the bottom of the hole, a "Blake" pump and hose being employed for that purpose. The cartridge, a tin canister inch in diameter, 15 inches long, was filled with explosive to within about an inch of the top, the exploder (fulminate of mercury) enclosed in a copper capsule, into which the insulated copper wires were passed, and to which they were secured by the maker, was inserted in the cartridge. This was sealed and attached to similar wires of sufficient length to reach the bottom of the hole and connect with the electric battery on the scow. The cartridge was next placed in a tin tube inch in diameter about 20 feet long, through one end of which a slit in the side extending the full length of the cartridge admitted the easy passage of the insulated wires; the latter were drawn tightly, passing along outside the tube, which was carefully lowered to the bottom of the hole. A wooden rod was gently pushed by hand through the tube, to keep the cartridge down, and the tube withdrawn. A quantity of explosive, varying from 2 lbs. to 5 lbs., in proportion to the depth of rock, was then poured through a...
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- 13 Sep 2013
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