Water-power; an outline of the development and application of the energy of flowing water . h helical blades, givingmotion to a horizontal shaft. The blades join a hub on theshaft, and are limited by an exterior rim. In some cases thisrim is made double and encloses a vacant space givingbuoyancy to the wheel and relieving the bearings of pressureexcept the thrust. The wheel is encircled by a stout frame toprotect it from injury. A small bevel-gear on the shaft givesmotion to a train of wheehvork enclosed in a box A with aglass cover. The ratchet-wheel shown is moved, one toothat a time, by a s
Water-power; an outline of the development and application of the energy of flowing water . h helical blades, givingmotion to a horizontal shaft. The blades join a hub on theshaft, and are limited by an exterior rim. In some cases thisrim is made double and encloses a vacant space givingbuoyancy to the wheel and relieving the bearings of pressureexcept the thrust. The wheel is encircled by a stout frame toprotect it from injury. A small bevel-gear on the shaft givesmotion to a train of wheehvork enclosed in a box A with aglass cover. The ratchet-wheel shown is moved, one toothat a time, by a spring-catch to which is attached a cord reach-ing to the surface of the water. A pull on the cord throws theclockwork out of gear, and the next pull throws it in. Themeter is shown as attached to a rod. The observer stands on THE CURREXT-METER. 539 a bridge or temporary platform over the watercourse. Afternoting the reading of the dial he places the meter in the waterat the required depth, guided by a graduation on the rod, A\iththe clockwork out of gear. An assistant holds the meter in. Fig. 234. Fig. 234(z. place. A stop-watch is commonly used for noting the time,but an ordinary watch docs very well. At the commencementof an even minute the observer pulls the string to throw thevvhcelwork in gear. After the lapse of a suitable number ofseconds he throws it out, raises the meter, and notes the dial. 540 MEASUREMENT OE WATER. As indicated by dotted lines the instrument admits the attach-ment of electric wires when required. An Acoustic Meter.—The writer, while in the service ofthe U. S. Engineer Department, had occasion to observethe working of current-meters. He became convinced thattheir chief source of difficulty and error lay in the means usedfor conveying their indications to the observer. Especially isthis the fact when the revolving shaft operates a train of wheel-work from which sediment cannot be excluded. The attemptto exclude it involves the use of a stuffing-box,
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthydraulicengineering
