Water-power; an outline of the development and application of the energy of flowing water . weight i. Similarly, gear 2 carries-a pulley with a band attached to a float in a chamber connectedwith the lower level. If now the water of the upper level rises,the bevel-gear i will rotate in the clockwise direction, and, throughthe intermediate gear 3 a rotation will be imparted to 4, viz., halfthe angular movement of i. The teeth of 3 simply walk overthe teeth of 2 without imparting any movement to 2. If thewater in the wheel-pit or lower level should at the same time riseto an equal extent, the ef
Water-power; an outline of the development and application of the energy of flowing water . weight i. Similarly, gear 2 carries-a pulley with a band attached to a float in a chamber connectedwith the lower level. If now the water of the upper level rises,the bevel-gear i will rotate in the clockwise direction, and, throughthe intermediate gear 3 a rotation will be imparted to 4, viz., halfthe angular movement of i. The teeth of 3 simply walk overthe teeth of 2 without imparting any movement to 2. If thewater in the wheel-pit or lower level should at the same time riseto an equal extent, the effect will be to rotate 4 back to its formerposition; but if the water in the lower level falls, the effect willbe to advance 4 still further in the clockwise direction. The-aggregate movement of 4 therefore is proportional to the changeof fall, and by suitable graduation the latter may be read from,the disk. THE WEIR. 553-^ The Weir.—Although the word weir or wear hasthe general signification of a dam, its meaning has latterly-been restricted to a dam specially designed to measure the. quantity of water passing over it. Equations (26) and (28)relate to the flow of water ov^er dams of ordinary form; but forexact measurements a form of weir is presupposed conformingto that from which the formula was deduced. Pacilities formaking such experiments have multiplied enormously of late,especially in scientific schools, and there is hardly any form ofweir or dam that has not been made the subject of exactdetermination of discharge. We will adhere, however, to thestandard form of measuring-weir. Fig. 245, presenting a sharpedge on the up-stream side, both on horizontal crest andvertical sides, after passing which the water leaps freely intothe air. The surface of the water approaching the weir takesa curved form, and the depth must be measured at a sufficientdistance up-stream to avoid the effect of this curve. It is foundthat a perforated pipe resting on the bottom of the channel,clos
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthydraulicengineering
