The improvement of rivers Volume 2; a treatise on the methods employed for improving streams for open navigation, and for navigation by means of locks and dams - Softcover
Synopsis
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. 1913 Excerpt: ...to be carried ashore, as far as practicable, leaving nothing loose on the crest. The design should also permit of maneuvers in case a sudden rise overflows the crest. Arrangements for temporary cofferdams for repairs to the movable portions should be provided with these structures, the simplest form being flash-boards supported by removable pins. A formula for the width of apron for a dam with a movable crest will be found on p. 375. The cost of the movable crests just described was as follows: Drum crests of the Monongahela River, $24.00 per foot run, or $8.00 per foot of height (total height 3 feet), not including operating machinery. Boule Crest of Dam No. 11, Muskingum River, $13.30 per foot run or $3-33 per foot 01 height (total height 4 feet). Shutters of Dam No. 5, Monongahela River, $8.00 per foot run or $2.66 per foot of height (total height 3 feet). Needle crests of the Kentucky River, $10.00 per foot run or $1.67 per foot of height (total height 6 feet). Up to Jan. 1, 1913, the movable crest of Dam No. II only-had been used, owing to the necessity for keeping the pool above Dam No. 12 at a low stage during the construction of Dams No. 13 and 14. An experience of about six years at Dam No. 11 indicates that this form of crest can be operated safely, but the fluctuations in the pool level, necessitated by the mancuvers for passing small rises and by complications from drift, are a constant source of uncertainty to navigation. Sluiceways and Drift-chutes.--With dams on rivers of small flood range some type of sluice is usually employed in lieu of a movable crest. The simplest form consists of a rectangular opening closed by needles, with intermediate piers if the sluice is long. For convenience in operation it is best to use hook-needles of square c...
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