1920) RURAL ENGINEERING. 387 



wells can be obtained, and that the ultimate head or depression necessary to 

 obtain this supply can be calculated with, fair accuracy. It is stated that the 

 present njetJiod of estimating the various unknown quantities connected with 

 tube-well water supplies appears to be based on entirely erroneous assumptions. 



Observations made on the subsoils of the Punjab have shown that the slopes 

 necessjiry to causo water motion have varied from 1 in 2G0 in moderately 

 coarse sand to 1 in 175 in. -fairly tine sand. With Hatter gradients in each tjT)e 

 of Siind there is no apparent motion. Capillary attraction interferes with the 

 true How. " Observations indicate that any lateral or forward moti(»n of 

 water, where the hydraulic gradients are slightly less than tho.se mentioned, 

 is so slow that for practical purposes it may be neglected, the actual velocity 

 probably not exceeding a few inches per day. When water is flowing through 

 sand the hydraulic gradient is a straight line as long as the sand is all of 

 similar grade and density and all cross sections on the line of flow are of 

 equal area." 



Tabular data are given on tlie permanent (U'piession head in tube-well 

 Installations, and the estimation of this factor is considered of the xitmost 

 Importance. 



Methods of irrigation and distribution of crops in irrigated areas, I-II 

 (Mcdios que se UtiUzan para Suministrar el Riego a las Ticrras y Dl-strihucidn 

 de los Ctdtivos en la Zona Regahle. {Madrid^: Mm. Fomento, Dir. Gen. Agr., 

 Minus y Monies, 1918, I, pp. VII I +732; II, pp. [U+SOO, pis. 6, figs. 76).— This 

 work, in two volumes, is a compilation by the Agricultural Consulting Board 

 of Spain of a large amount of information on iri'igation practice reported by 

 the agricultural engineers of 40 Spanish provinces. It includes data on water 

 supplies, conveyance and distribution of water, duty of water, irrigation struc- 

 tures, soil moisture and methods of irrigating different crops, and the results 

 of numerous irrigation experiments with certain crops. 



Public Roads (U. S. Dept. Agr., Public Roads, 2 (1920), Xos. 21-22, pp. 48, 

 figs. 9 ; 2S, pp. 32, figs. 22). — These numbers of this periodical contain the fol- 

 lowing articles : 



Nos. 21-22. — Relations of the States with the Bureau of Public Roads, by 

 O. P. Coleman ; Federal Control and Aid for Highways — Its Results, Merits, 

 and Limitations, by T. H. MacDonald ; Making Highways Ornamental and 

 Useful, by .T. A. Hazelwoo'd ; Design of Highway Drainage Structures, by C. 

 Older; The Marking, Signing, and Making Safe of a State Highway System, 

 by I>. H. Neilsen ; Maps of State Highway Systems for the I^se of the Public, 

 by M. W. Watson ; The Alignment, Grade, Width, and Thickness in Design 

 of Road Surfaces, by C. M. Upham ; Highway Administration, by G. H. Biles ; 

 A National Program for Highway Research, by A. Marston ; Shall Contract 

 Bonds Be Eliminated? by W. G. Thompson; State Testing Engineers and 

 Chemists Meet in Washington ; Interesting Federal-aid Project ; Graphical 

 Progress Report in Federal-aid Road Construction ; and December and January 

 Federal Aid, 



No. 23. — This number of this periodical contains the following articles: 

 Mechanical Concrete Road Finisher, by H. G. McKelvey (see p. 388) ; A Con- 

 venient Method of Computing Cross Sections, by G. T. McNab (see p. 388) ; 

 Sub.stantial and Attractive Guard Rail on Oregon Road ; Machinery Replaces 

 Hand Labor on Minnesota Project, by G. C. Scales; Concrete Pressure against 

 Forms, by E. P. Smith (see p. 388) ; Proper Consistency of Bituminous Ma- 

 terials In Highway Engineering, by P. Hubbard; Federal-aid Allowances — 

 Project Statements Approved in February, 1920; and Tests of Road-building 

 Rock In 1919. 



2482"— 20 7 



