United States Congressional Serial Set Volume 2866 (Paperback)

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. 1891 edition. Excerpt: ...experience seemed to show the inadequacy of such means, and the original plan is modified so that instead of the last. 6 feet of masonry there is to be a wooden shutter hinged, which will be raised in low water, but lowered in floods, and thus cause the scouring out of a 6-foot channel above the dam. STORAGE ON THE NORTH FORK OF AMERICAN. Three sites offer good facilities for the erection of storage dams j the first or uppermost in a trap rock gorge below Rice's Bridge; the second at a similar gorge a mile and a half above tbe North Fork Bridge; and the lowest at a granite gorge 3 miles below Gwynn's or Rattlesnake Bridge. SITE OPPOSITE CAPE HORN. This upper site is at the lower end of the 8-mile grade, extending from the Gold Run dumps to opposite Colfax. The whole distance is tilled with coarse gravel, ranging in size from bowlders and cobbles to medium sized gravel, the heaviest material predominating at the dumps, and heavy to medium gravel at the lower end, the depth from 5 to 40 feet. The grade varies from 36 to 46 feet per mile, and the width in general from 150 to 200 feet. The sidehills rise 1,200 to 2,000 feet for considerable heights at angles from 30 to 35 degrees. The country rock is clay shale or slate in the upper and a trap below Rice's Bridge. The notes of the line of levels run over this stretch in 1881 by the county surveyor are appended. Tbe dam site is a narrow trap gorge a half mile below Rice's Bridge, the crossing of the road from Colfax to Iowa Hill. The bottom width is 'JO feet and side slopes 37 and 35 degrees, the faces straight, smooth, hard trap for several hundred feet in length and 50 feet in height. As the grades above are rather steep, only the coarser part, about 30 to 40 per cent, of the debris can be...