118 EXPERIMENT STATION RECORD. [Vol.40 



the diurnal rainfall distribution at Columbus, Ohio, which is assumed to he 

 typical of central Ohio, and a comparison is made with the rainfall distribution 

 at Lincoln, Nebr., as reported by Kincer (E. S. It., 36, p. 717). 



It is shown in general that the precipitation as measured at Columbus occurs 

 for the most part in the form of light beneficial showers, and that the greatest 

 amount falls between about noon and 7 p. m., with the actual maximum between 

 4 and 6 p. m. It is thought that this fact lessens evaporation and tends to 

 increase the efficiency of the rainfall. 



Frequency of subnormal rainfall in August {U. S. Drpt. Agr., Xat. Weather 

 and Crop Bui., No. 21 (1918), pp. 2, 3, 7. fig. 1). — A chart is given and briefly 

 discussed which indicates for different sections of the United States the per- 

 centage of times in the 20-year period from 1895 to 1014 that the total rainfall 

 in August was less than half the normal. The chart shows that " from the 

 Rocky Mountains westward and in southwestern Texas deficiencies of this 

 amount in the August rainfall are of frequent oc cu rrence, except In most of 

 Arizona and portions of the adjoining States, where the rainy season continues 

 during this month. The large percentages of subnormal rainfall shown on the 

 chart for this area are due to the fact that the amounts in tins month are 

 usually very small, bul occasionally comparatively heavy falls occur which un- 

 duly magnify the monthly averages COD DUted for a period of years. In portions 

 of Arizona, the central Rocky Mountain area, the central Mississippi Valley, 

 eastern Kansas, and from eastern Nebraska northeastward to central Wiscon- 

 sin, and also along the central and east (iulf coast, as well as in parts of 

 Georgia, the Carolines, Virginia and Kentucky, Ohio, Pennsylvania, and Massa- 

 chusetts, the August rainfall was less than half the normal only twice during 

 the 20-year period under consideration; while locally in some of these areas 

 deficiencies of this amount were not recorded during the entire period. EJast 

 of the Rockies rather Large percentages are found from Oklahoma southward, 

 in northeastern Mississippi, southern Iowa, the western portions of the DakotaS, 

 and in Montana: while in California, Oregon, and much of Nevada and eastern 

 Washington the rainfall in August was less than half the normal from 50 to 

 SO per cent of the years comprising this period." 



Problems of denudation, H. JEFFREYS (I'hil. Mag. ami Jour. Bci., '.'. ter., -W, 

 [1918), No. 212, pp. 179-190; aba. in 8oi. Ab$., Beet. A-Phy$., 21 {1918), No. 259, 

 pp. \10, Ifll). — "The problem of denudation by rain freely running off a surface 

 is treated dynamically. The movement of surface water is controlled by gravity 

 and friction; hydrostatic pressure and inertia are negligible. Water, therefore, 

 always moves along the lines of greatest slope. In mountainous regions the 

 friction may be due to turbulence, but usually to viscosity. The motion is 

 completely determinable given the form of the land and the rain distribution, 

 in the case of viscous How the rate of denudation Is proportional to the product 

 of the depth of water and the tangent Of the Slope. If this is constant the sur- 

 face will sink at a uniform rate." 



Hail protection. !■'. CouBTX {Prog. Agr. et Vit. {B4. VBst-Centn I, 59 {1918), 

 No. 15, pp. ///-}}' s '^. — This is a summary of results of experiments from 1912 

 to 1017. The general conclusion from this review is that the evidence is not 

 conclusive as to the effectiveness of cannonading as a protection against hail. 



SOILS— FERTILIZERS. 



Reconnoissance soil survey of the Lower San Joaquin Valley. Cnl.. .1 W. 



Nelson, J. E. Guernsey, L. C. Hoi itn, and ES. C. K< km \nn if . 8. /»<•/>/. t<o-., 



Idv. sin, is n< hi Oper. Bur. Soils, 1915, pp. 151, pU. .1 fig. l. hi-//, f). This 



survey, made in cooperation with the California Experiment station, deals 



