THE IBBIGATION AGE. 



179 



very cheaply by modern machinery where the water 

 supply is adequate and a proper arrangement of ditches 

 and reservoirs is made to economize it, the universal ten- 

 dency being always toward waste. 



WHERE* OPEN WELLS ABE A SUCCESS. 



.Ordinary open wells are more successful in clay 

 and stone than in sand, there being far less liability of 

 the water running out, the bottom of the well being a 

 retaining reservoir, which may be greatly enlarged by- 

 tunneling out to any safe distance Jnto the water table 

 or water stratum. Where the water stratum is in sand 

 it is better to use screen points, that is, tubing with 

 perforated ends, which admit the water but keep out 

 the sand. Several of these screen points may be run 

 down into the water-bearing sand stratum at a suffi- 

 cient distance to prevent one robbing the other, and 

 all be connected with a suction pipe. Experience tells 

 that these screens should be run down to the bottom 

 of the water-carrying sand if possible, and that in 

 any event they should be sized according to the depth of 

 the strata. 



To accomplish this purpose successfully in wells 

 an open well largo enough for two men to work in 

 should be sunk down to the sand and curbed to pre- 

 vent caving. Then by driving ordinary gas piping as 

 a casing for the screens and boring with a common 

 auger, the screens may be lowered to any depth, or if 

 the water-bearing sand is very deep a succession of 

 screens may be put down on top of each other to en 

 large the water supply. 



Assuming the water supply to be adequate for the 

 purposes of reasonable irrigation from a well, the next 

 question is how to raise the water in the most eco- 

 nomical manner. Economy is wealth in irrigation 

 more than in any other business. Horace .Greeley 

 boasted that he raised the finest potatoes in the country, 

 but they cost him about $2.50 each, and his milk cost 

 him the same price as the finest imported champagne 

 wine. 



WINDMILL IRRIGATION. 



Aside from human muscle and ox or horse-power 

 drawing water in the ancient fashion, and still practiced 

 in Asia, the simplest and least expensive method of 

 raising water is by windmill. A sixteen-foot windmill 

 connected with a storage reservoir will raise water 

 enough to irrigate fully ten acres. But the windmill 

 could not deliver the amount of water demanded if the 

 supply were used at the same time as the pumping, 

 hence the necessity of constructing a reservoir in which 

 to store the water. With this reservoir the windmill may 

 be made to pump constantly and provide a supply of 

 water against the time of need. One with a capacity 

 of several millions of gallons may be constructed with- 

 out great expense, as will be described on another 

 page. 



Instead of a windmill, a centrifugal pump may 

 be used which will raise water to a height of about 

 fifty feet at a cost of less than 30 cents per million 

 gallons. These pumps arc geared to be operated either 

 by steam or gasoline engines. Where there is plenty of 

 fuel or coal is accessible, steam power is advisable, but 

 where fuel is scarce or expensive the use of gasoline is 

 naturally more economical. 



In central Asia, which includes Persia and the 

 surrounding countries, the water of the brooks and 

 mountain streams seeps through the porous conglom- 

 erate formation and disappears deep in the earth. 



forming subterranean streams. Owing to the nature 

 of the soil, canals and ditches would not be of much 

 utility, and hence recourse is had to a system of irri- 

 gation by means of a group of deep wells dug at the 

 base of the mountains. These wells are connected to- 

 gether by underground galleries which terminate in a 

 large well, which answers the purpose of a reservoir. 

 Along down the valley some distance from the large 

 well are established a series of dry cisterns about 150 

 feet apart, the bottoms of which are lower than that 

 of the well reservoir. The depth of these cisterns di- 

 minishes gradually until the last one is reached, the 

 depth of which may not exceed eighteen inches. 



All of these wells and cisterns are connected to- 

 gether by galleries large enough for a man to pass 

 through in a stooping position. This arrangement of 

 wells and cisterns with their connecting galleries is 

 sufficient to supply an open canal which carries water 

 to the valley, the whole length of the irrigating sys- 

 tem ranging from two to thirty miles. Direct conduits 

 and piping have been used, but discarded owing to the 

 tremendous depth of the wells and the fact that the 

 water is seepage water, not collecting fast enough to 

 be piped. Sometimes water is run into these subter- 

 ranean reservoirs and the water supply thereby aug- 

 mented largely. 



This system of connecting a number of wells with 

 tunnels or galleries has been tried in the United States 

 and has proved satisfactory in providing an increased 

 water supply by means of an underground reservoir. 

 Deep cisterns have also been tried for the same pur- 

 pose, but the most common practice is to run a tunnel 

 or gallery out from the "bottom of a single well, in 

 fact several of them, if the formation will permit. If 

 sunk on high ground a flow of water may be secured 

 from below by piping, otherwise pumping must be re- 

 sorted to, which is the case when the wells are very 

 deep. 



All the rising subterranean waters are essentially 

 artesian, whatever the depth of the bore of well which 

 strikes the vein. 



An artesian well is nothing more than one 

 branch, end or leg of a tube or pipe, the other end, or 

 intake, of which is at a greater or less elevation above 

 the outlet. The fact that such wells are so called from 

 the city of Artois, in France, where deen flowing or 

 spouting wells were first sunk or bored, has nothing to 

 do with the characteristics of the water supply, pro- 

 vided it rise in the well, flows over the mouth or spouts 

 up into the air. In such cases it is evident that the 

 water is not what is usually called surface, seepage 

 or drainage water, although there is very little differ- 

 ence. 



The value of the artesian well, which is bored deep 

 into the earth, lies in the fact that its elevated source 

 is constantly being replenished with a supply of water 

 greater than that used for irrigation or other purposes. 

 In the case of water from a saturated soil, or water 

 that has percolated down through porous ground 

 through cracks and crannies to find reservoirs, the sup- 

 ply depends upon the amount of rainfall or seepage. 

 In ordinary wells, to draw water by constant pumping 

 for adequate irrigation is to soon exhaust the stored 

 supply, or ground water, there being no source to re- 

 plenish it. 



But in the case of artesian wells in the arid re- 

 gions the source of the subterranean water which rises, 

 flows over the mouth or spouts up into the air, is in 



