320 Irrigation and Drainage 



THE USE OF RESERVOIRS 



To employ wind power for irrigation to the best advantage, 

 a reservoir is required in most cases. There are localities on 

 the seashore where nearly every day a sufficient breeze springs 

 up to drive the windmill, and in such cases, if the supply of 

 water is large, the lift small, and the demand for water moder- 

 erate, the ground for many crops may be, laid out in such a 

 manner that a system of rotation may be followed, and the 

 reservoir dispensed with ; but in such cases the time -and 

 attention required for the distribution of the water will usually 

 be greater than where a reservoir is used. 



The reservoir should be placed where it is high enough to 

 serve all the ground to which it is desired to supply water, but 

 it is very important to keep it just as. low as possible, because 

 since the economic lift of the mill is only 10 to 25 feet, every 

 foot saved on the height of the lift into the reservoir is a large 

 percentage gained in efficiency. The elevated wooden tanks, 

 placed on towers far above the ground to be irrigated, are very 

 expensive in themselves, and greatly reduce the area which a 

 windmill can irrigate. 



In constructing a reservoir where soil and subsoil are 

 reasonably fine and close, the first step is to remove from the 

 area all rubbish and coarse litter that may interfere with the 

 close packing of the soil. The land upon which the walls of the 

 reservoir are to be built is then plowed, leaving a dead furrow 

 in the center, which may be filled with water until the whole 

 area is thoroughly saturated. When the water has drained 

 away sufficiently to permit of teams driving over the ground, 

 the soil should be thoroughly trampled and puddled, after which 

 dirt from the bottom of the reservoir may be scraped on and 

 trampled with the teams continuously and thoroughly. It is 

 recommended as an excellent plan to maintain the sides of the 

 walls higher than the center, but all portions nearly enough 

 horizontal, so that water may be pumped into the furrow at 

 night, to help in settling the materials more closely and render 

 the puddling more complete. 



