MODES OP APPLYING WATEK. 121 



millions of acres upon the banks of streams that could 

 be made to bear crops of grass permanently, with the 

 greatest profit, at a comparatively small outlay per acre. 

 It is where the surface to be irrigated is large that the 

 process of irrigation is the cheapest. "Where a stream 

 flows naturally above the surface of a portion of the 

 neighboring land, the cost of irrigating the land will be 

 very small, and the cost per acre will be the minimum 

 when the supply of water is abundant and the area to be 

 watered is large. In this case no dam will be needed, or 

 at most such a one as can be made at a small expense and 

 maintained with little trouble. A simple barrier of stones, 

 or a few planks, or a log laid across the stream and held 

 in its place by a few stakes driven in the ground, will suf- 

 fice to divert the flow into a canal, which will lead the 

 water with the least possible loss of level to the ground 

 to be irrigated. A narrow valley having a stream mean- 

 dering through its center, and with sides gently sloping 

 toward the stream, is peculiarly well adapted for irrigation. 

 The whole length of the valley, from its head to its out- 

 let, may be made a succession of meadows. The small 

 tributary streams of the valley will be made to aid in the 

 work and contribute their share to the general supply of 

 water. 



Should the streams be subject to early Spring and late 

 Fall freshets, so much the more valuable they will be. 

 Every flood will bring down a large amount of solid matter 

 to be deposited as a fertilizer upon the soil. The water of 

 floods is also highly charged with soluble matters which 

 are rendered up to the soil through which it is made to 

 percolate. The only disadvantage is, that should a flood 

 occur when the grass is nearly ready for cutting, a con- 

 siderable quantity of sand may be deposited upon it, and 

 much of the crop may be lodged. But this difficulty is 

 unavoidable, and would occur in any case, and must be 

 submitted to as one of the drawbacks incident to the 

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