The Mining Industry in the Territory of Alaska During the Calendar Year 1916 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...CREEK DREDGING CO. The dredge erected on Cache Creek during the past spring represents the first serious attempt at gold dredging in this part of the Territory. The bedrock includes slates, graywackes, sandstones, and shales, with occasional beds of lignite. The creek is comparatively shallow, its average depth being approximately 6 feet, so the dredge has a large hull, 87 feet long, 54 feet beam, and 7 feet deep, for shallow draft. The planks of the bottom are 4 by 12 inches, those on the sides 6 by 12 inches, and the deck 3 by 12 inches. The winch deck is 30 feet above the main deck and the pilot deck is 12 feet above this. The spuds, made of wood reinforced with steel, are 44 feet long and weigh 11 tons each. The 65 close-connected 7-foot buckets have manganese-steel lips; and although the dredge has a capacity of 3,000 cubic yards in 24 hours, the management has based its plans on an output of 2,000 cubic yards, on account of the shallow ground and the number of bowlders. The latter have retarded the speed of the dredge, but have not proved a serious hindrance, as they are not large enough to require special devices for handling. With the present number of buckets, the dredge can dig 30 feet below water line, though it probably will not be called upon to work at anywhere near this distance on this part of the creek. The gravel from the buckets falls over an 11-inch grizzly into a 48-inch flume, 108 feet long. The grade of the flume is adjustable, though the best results are obtained by keeping it at a fall of approximately 1 inches to the foot. The riffles are 2 by 4's capped with f-inch manganese-steel plates and are set If inches apart. A 6-inch centrifugal pump supplies wash water at the grizzly and an 18-inch centrifugal pumps directly to the flume....