120 



IRRIGATION FARMING. 



Weir Table. The following table may be of st-rv- 

 ice where the delivery is such that it can be measured 

 over a rectangular weir, as described under the foregoing 

 caption. 



THE CALIFORNIA WEIR TABLE. 



To use the table measure the depth of water in 

 inches over the weir. From the depth so measured find 

 in the table the miner's inches flowing for each inch of 

 width in the weir opening. The width of the weir open- 

 ing in inches multiplied by miner's inches in the table 

 gives the miner's inches flowing over the weir. Multiply 

 the miner's inches by .02 to obtain the cubic feet a sec- 

 ond or .04 for the acre feet a day, or by 0.5 for the acre 

 inches a day, or by 4 for the acre feet in 100 days, or by 

 9 for the gallons a minute. 



Gauging Large Streams. Frequently it is im- 

 possible to construct even a temporary weir on account 

 of the large quantity of water the stream carries. Meas- 



