GOLD DREDGING (CLASSIC REPRINT)

Excerpt from Gold DredgingEnumeration of these latter, howe er, may serve to mark the failures of inventors in the past, and thus warn their successors against similar attempts. Undei the heading of obsolete machines may be classed the pneumatic caisson, the submarine boat, the hydraulic. Elevator, and the vacuum dredge. The pneumatic caisson was on the principle employed in making cylinders for the piers of bridges. In it, the diver was let down so as to work direct on the bed of the river. This might be all right for a rich patch, the situation Of which was exactly known, but, for men-day work, where much barren stuff had to be lifted, it proved a lamentable failure. Submarine boat, on the principle of the diiing bell, is said to ha e been con structed, but never used. Dredging operations using the principle of the hydraulic elevator were attempted on the Chestatee River, Lumpkin co., (ia., but proved unsuccessful, the elevator being out of place in a river bed, many feet below the lewl Of the water, Since most of its work consisted in raising water that did not contain gold. The Bazin dredge was one of the first worked on the vacuum system. The principle upon which the vacuum in this machine was obtained lay in the difference of level between the water outside and the bottom of the bull, in consequence of which the water was forced up the suction-pipe projecting down from the hull to the river bed, and in doing SO carried up the auriferous sands. A centrifugal pump re ceived all the matter forced into the tube, and, adding fresh impulse to its progress, delivered it to the washing appliances. A disad vantage Of this form of dredge was that it required a considerable depth of water in order to produce the requisite amount of vacuum for efficient work. This defect led to the introduction of steam vacuum dredges. The boat was fitted with a boiler and steam pump, 0, each connected with a vacuum chamber, from which projected the.About the Publisher