Utilizing Storm Waters 311 



which permits a, considerable difference between the long and 

 short legs of the siphon. 



To start the action of the siphon, the long arm must be filled 

 with water ; then, as this descends again, more water rises 

 through the suction arm passing into the receiver (a) and through 

 the check-valve (c) into the regulator (b). In passing the check- 

 valve, the drag of the water closes it, and thus stops the current ; 

 but no sooner has this occurred than the momentum of the water 

 opens the puppet valve (d), and a portion escapes into the 

 storage tank or reservoir. While the water has been discharging 

 through the puppet valve and coming to rest, the fall of water 

 in the discharge arm has created a vacuum in the regulator, 

 which permits the atmospheric pressure on the corrugated heads 

 to force them inward and open the check-valve, thus starting the 

 flow again. These pulsations are very rapid, ranging from 150 

 to 400 per minute, so that a nearly continuous flow is maintained. 

 Wilson states that these water elevators have been built with 

 sufficient capacity to deliver 8 acre -feet in 24 hours, an apparatus 

 of this capacity costing $1,200. 



UTILIZING STORM WATERS FOR IRRIGATION 



There are many sections of country where the topography is 

 such as to permit storm waters to be caught by individual farmers 

 in reservoirs formed by cheap earth dams thrown across the 

 axis of a run, draw or ravine, and the floods produced by rains 

 held back and used in irrigating lands below in times of drought. 

 This is a veiy common practice in many parts of Europe, where 

 the collected waters are oftenest used on meadows. Suitable 

 arrangements are made for taking out the water, and a waste 

 weir is provided by which the water may escape before the height 

 of the dam has been reached. 



Where water is supplied to large districts, the use of dams 

 with reservoirs is very common, especially on. streams which are 

 subject to large fluctuations in volume during the irrigation 

 season. 



