320 EXPEEIMENT STATION EECOED. 



Ariz,, during the winters of 1910-11 and 1912-13 " upon two areas, alike in 

 all respects, except that one was forested and the other naturally treeless." 



The results, reported in detail, indicate that there was no apprecaible differ- 

 ence in the total amount or density but great difference in distribution on the 

 ground of snow in the forested and nonforested areas. The rate of melting 

 in winter was greater in the forest than in the open. Melting in spring was 

 most rapid and the run-off greatest in the open. The snow disappeared more 

 gradually and the absorption and retention of water by the soil was greater 

 in the forest than in the open. 



The authors conclude in general " that the value of forest cover in the con- 

 servation of snow waters is great, even when that forest cover is of such 

 an open and broken character as the typical western yellow-pine forest on 

 which observations were made in this study." Commenting upon this study 

 and the deductions drawn from it, officials of the Weather Bureau question 

 whether certain of the conclusions drawn, especially those relating to the causes 

 of difference in conservation of snow in the forested and open areas, are suf- 

 ficiently supported by the data presented. 



Atmospheric influence on evaporation and its direct measurement, B. E. 

 Livingston (Mo. Weather Rev., 7/3 {1915). No. 3, pp. 126-131, figs. 2).— This 

 article deals briefly with some general principles of atmometry and discusses 

 the relative merits of different types of atmometers, especially the porous clay- 

 cup atmometer. It is stated that the latter " possesses all the advantages over 

 the free water surface that are possessed by the Piche, Piche-Cantoni, and 

 Bellani instruments. Its main advantage over these instruments lies in this, 

 that its surface projects up into the air and is exposed equally to wind action 

 in all directions. Its surface is somewhat similar to that of plants, which is 

 also the surface of a water-imbibed solid, and its exposure to the surrounding 

 aerial conditions is similar to the mean exposure of the surfaces of the foliage 

 of an entire plant. For this reason it has proved especially valuable in studies 

 bearing upon water loss from i>lants. The rigidity of the cups also makes them 

 more satisfactory than the somewhat flexible paper disks." 



A bibliography of literature relating to the subject is appended. 



Monthly weather periodicity, Y. Koppen (Mo. Weather Rev., JfS (1915), No.Ji, 

 pp. 179-lSl). — ^^This article adduces evidence to show that there is no weather 

 periodicity due to the influence of the moon. 



Influence of the moon on weather (Mo. Weather Rev., J/S (1915), No. If, 

 p. 182). — ^A brief reference is here made to a memoir by G. Wagner which con- 

 tains a critical summary of modern scientific investigations on the possible lunar 

 influences on terrestrial weather. This refutes the popular belief that this influ- 

 ence is sufficiently sti'ong to permit of its direct unaided observation, and that 

 one can even deduce weather forecasts from it. 



Monthly Weather Heview (Mo. Weather Rev., 43 (1915), Nos. 3, pp. 99-157, 

 pis. 11, figs. 6; 4, pp. 159-209, pis. 8, figs. 27).— In addition to weather fore- 

 casts, river and flood observations, and seismological reports for March and 

 April, 1915; lists of additions to the Weather Bureau Library and of recent 

 papers on meteorology and seismology; notes on the weather of the months; a 

 condensed climatological summary ; and the usual climatological tables and 

 charts, these numbers contain the following articles : 



No. 3. — The Total Iladiation Pteceived on a Horizontal Surface from the Sun 

 and Sky at Washington, D. C. (illus.), by PL IL Kimball; Solar Radiation In- 

 tensities during January, February, and March, 1915, and the Total Solar and 

 Sky Iladiation during March at Washington, D. C, by PI. PI. Kimball; Thermo- 

 isopleths for Washington, D. C. (illus.), by 0. Abbe, Jr.; The Influence of a 

 Western Yellow Pine Forest on the Accumulation and Melting of Snow (illus.), 



