DUTY AND DIVISION OF WATER 355 



Naturally, a different plate must be made for each length 

 of weir. Once such plates are installed, however, the 

 labor of reading weirs is reduced to a minimum. The whole 

 question of weir measurements is now being critically 

 examined at the Colorado Experiment Station, in cooper- 

 ation with the United States Department of Agriculture. 

 The weir in some form will undoubtedly be the standard 

 measuring device of the irrigation world. 



214. Divisors. With the Cippoletti weir, the division 

 of water may be performed easily and accurately. Since 

 the slanting sides of the Cippoletti weir allow for the 

 contraction of the water, the quantity of water flowing 

 over any portion of the crest is approximately equal to 

 that flowing over any other similar portion. Therefore, 

 by placing a partition below the weir to divide the crest 

 into certain proportional parts, the stream itself is divided 

 into similar proportional parts. A beveled board or a 

 sharp-edged partition of some kind is placed at right angles 

 to the crest and so low as not to interfere with the free 

 circulation of air around the jet of water. If the weir 

 crest is 3 feet long and a partition is placed 1 foot from 

 one end of the crest, the water is divided into two parts, 



n " ***f"* 



cirrouc-r 



FIG. 100. Scale to be screwed on side of Cippoletti weir. This shows at a glance 

 the quantity of water passing over the weir. 



