PRACTICAL IRRIGATION. 



Although the general subject of irrigation and the reclaimation of 

 arid lands is discussed widely, and has come to be one of the great 

 questions before the people of this country, yet there is probably a 

 considerable number of persons who have a very vague idea as to the 

 methods by which the water is brought to the land. A few element- 

 ary statements may, therefore, not be out of place. 



As a fundamental proposition, it may be said that irrigation on 

 any considerable scale is possible only by means of gravity systems 

 and open ditches. In other words, the amount of water required is so 

 great that it will not pay to bring it to the agricultural lands unless it 

 can flow through ditches or channels dug into the surface of the 

 ground. In exceptional instances pumping has been employed, and 

 the water conveyed through pipes, as is customary in municipal 

 supplies. 



In order to irrigate land, it is necessary to dig a ditch leading 

 from a stream whose slope is so great that the ditch, following its 

 bank on a lesser grade, can gradually be diverted from the river. If, 

 for example, the stream falls at the rate of 10 feet per mile and the 

 ditch only one foot, it is evident that the water in the ditch only one 

 foot, it is evident that the water in the ditch will be 9 feet above that 

 in the river at the end of the first mile, and in 10 miles will be 90 feet 

 above the river, and usually, looking down over a large extent of bot- 

 tom land. If now allowed to escape from the ditch, it will find its way 

 back to the river across the intervening low lands. Successful irriga- 

 tion consists in guiding this water in Its journey back to the river in 

 such a way that it will cover the largest area of land, saturating it to 

 the proper degree. 



The methods by which the water is thus conducted are numerous, 

 the water in the supply ditch, following the contour of the land, is 

 allowed to escape in temporary ditches, and from these it is turned 

 out and guided by a shovel, so that it flows outwardly along the slope 

 of the land and finds its way by innumerable tiny rivulets down the 

 slope. Considerable skill is required to distribute the water uniformly 

 in this so-called "wild flooding," and as a rule the lower parts of the 

 field receive an excess of water while the higher portions are left dry. 



The supply ditch follows the general contour, dropping slightly; 

 below this the land is divided into rectangular fields, each of a size 

 such that by means of a low ridge say 2 feet in height the water 

 can be held back and flooded over the entire surface. If the slopes 

 are steep these checks or little leeves must be near together, while if 



