l62 IRRIGATION FARMING. 



flow one-tenth of twenty feet, or two feet. Therefore, 

 the velocity of the stream is two feet a second. This, 

 multiplied by the cross-se<5lion, will give the approxi- 

 mate discharge, or the amount of water, flowing in the 

 stream. Suppose in the case given that the cross-sec- 

 tion was eight square feet, then the discharge would 

 be two, the velocity, multiplied by eight, the cross- 

 se(5lion, which equals sixteen cubic feet a second. This 

 is not the exa(5l amount flowing in the stream because 

 the water flows fastest near the surface and in the cen- 

 ter. The float naturally takes the velocity of the 

 swiftest portion of the current. The velocity is 

 retarded at the sides and bottom by fri<5lion. If a more 

 exadl measurement is required the result if multiplied 

 by between .80 and .90, according to the roughness of 

 the bank and amount of obstrucftion in the channel, 

 will give the amount of water flowing in the stream 

 near enough for ordinary purposes. For example : 

 using .80 as a fadlor in the previous case, we have 

 .80 multiplied by 16 or 12.80 cubic feet as the acflual 

 discharge. The judgment of the operator must be 

 exercised in the use of this fadlor. Ordinarily with 

 common dirt banks a fadlor of .85 will be nearly cor- 

 redl. By the use of this simple but efficient method 

 any water consumer may ascertain for himself whether 

 or not he is receiving the quantity of water to which he 

 is entitled. 



A California Weir System. — It often happens 

 that there is great trouble in the canal system in divid- 

 ing the water equitably among a number of irrigators, 

 patrons of the ditch. Consumers are expe<5led to bear 

 their proportion of loss by seepage and evaporation 



