718 EXPERIMENT STATION RECORD. [Vol.36 



plains region where the rainfall is limited it is of great importance that the 

 rains occur largely during the night, when they will do the maximum amount of 

 good with the least interference with farm worli, especially the harvesting 

 and thrashing of wheat, which is the principal crop of the region. 



Slope and valley air temperatures, W. R. Blaib (Reclnm. Rec. [U. S.], 8 

 (1917), No. 1, pp. JtO, 41; U. S. Mo. Weather Rev., U {1916), No. 12, pp. 677- 

 679). — From a study of the results of three or four years' observations of 

 mountain and valley temperatures in the vicinity of Mount Weather, Va., 

 and by means of captive balloons at Lone Pine and Mount Whitney, Cal., the 

 author concludes that " a little observation on the slopes of a given valley at the 

 time of injurious frosts in the late and in the early autumn should serve 

 to determine with sufficient exactness the height on the slopes above which, 

 for some distance at least, the greatest freedom from such frosts will be ex- 

 perienced. The easiest and most direct way of making these observations is to 

 expose thermographs at different altitudes on the slopes. The balloon is not 

 needed because the upper surface of the cold-air mass in the valley Is nearly 

 level, possibly a few meters lower over the middle than at the sides of the 

 valley. This upper surface has been found at 100 to 300 meters above the valley 

 floor at different times of the night and in different localities." 



Types of anticyclones of the United States and their average movements, 

 E. H. Bowie and R. H. Weightman {U. S. Mo. Weather Rev., Sup. 4 (1911), pp. 

 25, pis. 73, figs. 7). — This paper is largely statistical, including, however, brief 

 descriptions of the types of anticyclones which prevail in the United States, 

 their courses, and the resulting weather and temperature conditions. No at- 

 tempt is made to deal at length with theories concerning their origin, etc., 

 further than to give " a statement of published views concerning the forces 

 that originate, maintain, and propel anticyclones across the United States at a 

 rate of speed that is little less than that of cyclones." 



Graphic method of representing and comparing drought intensities, T. T. 

 MuNGEK (U. S. Mo. Weather Rev., 44 (1916), No. 11, pp. 642, 643, fig. i).— The 

 construction and use of diagrams consisting of a series of right-angle triangles 

 whose height and base are both proportional to the duration of the drought is 

 described. 



Frequency curves of climatic phenomena, H. R. Tolley (V. S. Mo. Weather 

 Rev., 44 (1916), No. 11, pp. 634-642, figs. 4).— The construction and use of such 

 curves are discussed. 



Monthly Weather Review (U. S. Mo. Weather Rev., 44 (1916), Nos. 11, pp. 

 611-669, pis. 9, figs. 17; 12, pp. 671-712, pis. IS, figs. ^).— In addition to weather 

 forecasts, river and flood observations, and seismological reports for November 

 and December, 1916; lists of additions to the Weather Bureau Library and of 

 recent papers on meteorology and seismologj- ; notes on the weather of the 

 months ; solar and sky radiation measurements at Washington, D. C, during 

 November and December, 1916; condensed climatological summaries; and the 

 usual climatological tables and charts, these numbers contain the following 

 articles : 



No. 11.— The Duration and Intensity of Twilight (illus.), by H. H. Kimball; 

 Von Bezold's Description of Twilight ; Mairan's Description of Anti-twilight ; 

 Explanations of the Western Purple Light and the Eastern Afterglow (Nach- 

 gliihen), by A. Heim; Twilight Phenomena in Arizona, September to December, 

 1916, by A. E. Douglass ; Twilight Colors at Mount Wilson, Cal., August-Septem- 

 ber, 1916, by W. P. Hoge; Solar Halo of September 28, 1916, at Miami, Fla. 

 (illus.), by R. W. Gray; Metric System for Aeronautics; Measurement of Hori- 

 zontal and Vertical Movement in the Atmosphere, by M. Tenani ; Daytime and 

 Nighttime Precipitation and Their Economic Significance (illus.), by J. B. 



