i68 



Nature-Study Agriculture 



Hillside 

 flooding 



Measuring 

 water for 

 irrigation ; 



many gophers, which make themselves a pest by bur- 

 rowing in cultivated fields. 



FIG. 132. A box used for measuring irrigation water. Each inch in width 

 of opening allows the escape of one miner's inch. 



Sloping land is often flooded without either furrows 

 or checks. The water is carried along the upper part 

 of the field in a trench, which may be winding in order 

 to have a gradual fall. The sides of the trench are 

 broken at places with a shovel, so that the water may 

 flow out and spread over the whole surface of the field. 

 This method of flooding is suitable for such crops as 

 grain, where furrows would be troublesome. 



There are several methods of measuring irrigation 

 water in order to know how much to pay for it, but in 



the miner's most irrigation districts water is paid for by the " miner's 

 inch," a unit of measurement that was used by the 

 Western miners in pioneer days (Figs. 131 and 132). It 

 is the amount of water which, flowing continuously, can 

 pass through a hole an inch square if the middle of the 

 hole is four inches below the surface of the water in the 

 measuring box. In some states the depth of water 

 used is four and a half or five inches. Of course, the 

 deeper the water stands above the outlet, the more the 

 pressure and the faster the flow. 



