QUANTITY OF WATER USED FOR IRRIGATION. 177 



the water is raised to a sufficient height; or a submerged 

 rotary or "propeller" pump raises the water; or a windmill 

 may be used. In short, where water can be procured, and 

 it can be used with profit upon the land, there is no reason 

 why it cannot be made available through the skill of the 

 engineer or the enterprise of the farmer; either by the force 

 of its own gravity, or by some mechanical application. 



The quantity of water used in irrigating farm crops, va- 

 ries from one cubic foot per second for 200 acres, to double 

 that quantity. That is, a stream of water flowing through 

 a gate having one square foot of area, or 144 square inches,, 

 at the rate of 60 feet per minute, is sufficient to water 200 acres 

 o*f land. But meadows consume a much larger quantity of 

 water than this. In some of the irrigated meadows in the; 

 South of France, where the climate is hot and dry, the ex- 

 traordinary quantity of water is poured over the grass, as 

 to be sufficient to cover the surface 1300 feet in depth in the 

 whole year. In other cases, water to the equivalent of a 

 total of 27 feet in depth has been used in 6 months of the 

 growing season. In general it has been found that the 

 more water that can be made to flow over the grass, the 

 greater will be the product. 



From what has been said in a previous chapter, on the 

 relation of water to the growth of plants, it is easily realized 

 how important it is to the farmer to make use of this prac- 

 tice of irrigation wherever and whenever he can; how it 

 may be made to secure and increase crops under the ordi- 

 nary circumstances of the farm culture, and as an aid to the 

 natural rainfall, and how, by the use of it, the desert may 

 be made productive of every crop of the farm, and to sup. 

 port an industrious and enterprising population, where for- 

 merly no useful plant could grow, and where the wild beasts 

 roamed and howled in search of their prey. Thus it is that 

 man has dominion over the earth and all that it contains > 

 and turns it to his uses, and for the good of his race, by all 

 the natural forces which his knowledge, experience, and 

 skill, enable him to make available for his purposes. 



