RURAL ENGINEERING. 885 



It is Stated with reference to tills method of irrigation thiit the manipulation 

 of movable irrigators requires much time, care, and power. This method of 

 so-called " rain pouring " encounters a great obstacle in the wind, it being found 

 that to limit irrigation to nonwindy days gives poor results, while on windy 

 days the loss of water is about 30 per cent. 



Conservation of water by storage, G. F. Swain (New Haven, Conn.: Yale 

 University Press, 1915, pp. XVII+SSJf, pis. 2, figs. 8fl).— This book presents a 

 course of lectures on water conservation by storage. The first chapter Is de- 

 voted to the general subject of conservation. The next four chapters are 

 devoted to the relation of the conservation of water to the conservation of other 

 resources and to a somewhat lengthy discussion of the water-power question, 

 reference being made to questions of federal control of water powers. Suc- 

 ceeding chapters deal with the technical aspects of water power development, 

 the relation of forests to stream flow, and floods and their prevention. 



With reference to the relation between forests and stream flow, the author 

 is of the opinion that forests act as equalizers of the flow of streams by 

 diminishing in general the frequency and violence of the freshets and increasing 

 the low-water flow. " We should exercise discrimination in the utilization of 

 our lands, cultivating for growing crops those which are best suited therefor, 

 and reserving for forests the steep slopes and mountain sides and other areas 

 uusuited for cultivation of crops. . . . There seems no question that foi-ests 

 do regulate flow, and that upon steep mountain sides especially they exercise 

 a restraining efi'ect upon run-off, and that they also in such locations are of 

 Inestimable benefit in preventing erosion of the soil. . . . Forests un- 

 doubtedly do something in this direction, but even if the entire country were 

 covered with forests, it is probable that at times there would be extreme floods 

 which would do great damage." 



Hints on irrigation: Small earthen storage reservoirs, W. M. Watt 

 (Rhodesia Agr. Jour., 12 (1915), No. 2, pp. 172-185, fig. i).— The author de- 

 scribes reservoir and dam construction and the use of weirs under Rhodesia 

 conditions for the benefit of irrigation farmers. 



Multiple-arch diversion dam at Three Miles Falls, Oregon, H. D. Newell 

 {Engin. News, 73 (1915), No. 21, pp. 1009-1012, figs. .}).— This article describes 

 the construction of a long, low multiple-arch reinforced concrete dam on the 

 Umatilla Project of the U. S. Reclamation Service. 



Tour of West discloses best practice in irrigation and power canal design, 

 C. A. Farwell (Engin. Rec, 71 (1915), No. 20, pp. 623, 624).— This article 

 reports an extended study of a number of irrigation and power projects In the 

 West to learn costs and to determine the best practice in the design and con- 

 struction of concrete linings for large canals. 



It is pointed out that slopes and lining thicknesses should depend on the 

 nature of local conditions and material encountered. Small deviations in align- 

 ment and cross section are considered Immaterial. See also a previous note by 

 Fortler (E. S. R., 32, p. 380). 



Transmission losses in unlined irrigation channels, S. Foetieb (Engin. 

 News, 73 (1915), No. 22, pp. 1060-1063, figs. S).— The author discusses the 

 various factors Influencing seepage, referring particularly to capillarity, depth 

 of water in the canal, velocity, sedimentation, and temperature of soil and water. 

 He disagrees with the opinion of Morltz (E. S. R., 30, p. 288) that the rate of 

 percolation of water through canal banks varies directly as the depth of water 

 In the canal, and briefly summarizes the results of a large number of seepage 

 measurements on canals to substantiate his argument. 



Capillarity is considered to be an important factor In connection with seepage, 

 and the gradual deposition of silt is thought to reduce seepage materially. 

 18522°— No. 9—15 7 



