BURAL ENGINEERING. 181 



" Rotation systems increase the duty and have many other advantages. 

 Most canals divert more water than is actually required, both early and late 

 in the season. 



" The amount of water that will produce the largest yield of a certain crop, 

 on a certain soil, is not always the economic duty. The value of land, the cost 

 of water, the value of the crops produced, and the cost of producing them, as 

 well as the amount of water that will produce the largest yield, must all be 

 taken into consideration when determining the economic duty for any project. 



" The expression of seepage losses as per cent per mile is misleading. Seep- 

 age losses should be expressed as the unit of loss per unit of area of canal 

 bed per imit of time. Losses in medium soil range from 0.5 of a cubic foot to 

 1.5 cu. ft. per square foot of canal bed per 24 hours. Evaporation losses for 

 canals are usually less than 1 per cent of the total loss. Losses are extremely 

 high in farm laterals carrying 1 second-foot and less. Canals should be 

 kept full of water and should be designed with as small a wetted perimeter as 

 possible in comparison to the carrying capacity. Porous irrigated laud above 

 a canal may cause it to gain instead of to lose. Dikes in a canal section, or 

 excessive velocities, increase seepage losses." 



The flow of water in artificial channels: Clean pipes, W. H. Echols {Univ. 

 Va., Bui. Phil. Soc, Set. Set:, 1 (1912), No. 10, pp. 243-265, pi. 1, fig. i).— Inas- 

 much as in actual practice a certain form of construction and material accom- 

 panies certain ranges of diameters in water pipes the author determines an 

 expression for the coefficient* of resistance to flow adapted to the whole group 

 as a function of the velocity and mean radius, using a theoretical assumption 

 as to the form of the function of the velocity and mean radius and the con- 

 stants determined from several hundred experiments on the flow of water in 

 pipes of copper, brass, tin, zinc, lead, glass, wood, tile, cast and wrought iron, 

 riveted iron, and cement. 



For comparative pun^oses the results of 400 other experiments are given in 

 tabular form, arranged according to increasing diameters and velocities, and 

 showing the loss of head per 1,000 ft. and the experimental constants obtained 

 in each case by the above formula and by the formulas designed by various 

 authorities. 



Irrig'ation by pumping' in western Kansas, F. D. Cobuen {Mo. Weather 

 Rev., Jfl {1913), No. 1, p. SI). — This article reviews the development of irriga- 

 tion by pumping from both deep and shallow wells in the valleys and uplands 

 of western Kansas. It states that in the Arkansas River Valley from Garden 

 City to Syracuse many shallow well pumping plants are in operation or being 

 installed. The depth to water in this valley is from 8 to 10 or 15 ft. It also 

 states that the uplands, which comprise by far the greatest acreage, can be 

 profitably irrigated by deep well pumping and that this practice promises by 

 far the greatest possibilities. 



" The developments and experiences of the past IS months seem to demon- 

 strate conclusively not only that water is available in western Kansas in im- 

 mense quantities from a sort of subterranean lake, but that it may be success- 

 fully and economically raised for irrigating quite extensive areas." 



Irrigation practice, with special reference to fruit growing: in the North- 

 west, W. L. Powers {Portland, Oreg., 1912, pp. 68, pis. 4)- — This pamphlet 

 deals with the movement of ground water, losses in soil moisture, measurement, 

 distribution, application, and duty of water, irrigation pumping, irrigation of 

 orchards and special crops, irrigation institutions, and cost and profits of irri- 

 gation. 



Irrigation experiment, Augstin {Mitt. Deut. Landw. Gesell., 2S {1913), No. 

 7, pp. 100-103). — A year's test was conducted on a German farm of a system of 



