19161 METEOROLOGY. 115 



critical 10-day period for corn is from August 1 to 10 and for potatoes from 

 July 1 to 10. The dominant weather factor for winter wheat was found to 

 be more difficult to determine than for the other crops. Contrary to the popular 

 belief, it was found that there was no benefit to winter wheat from a snow 

 covering or damage from lack of it. A snowfall in January appeared to be 

 favorable, but, contrary to the usual opinion, snowfall in March was decidedly 

 detrimental to winter wheat. 



In the author's opinion " one of the first developments of agricultural meteor- 

 ology should be to find the critical period in the growth of the various staple 

 crops in different sections of the country." 



Stories of the atmosphere, R. Nunn (U. S. Dept. Agr. Yearbook 1915, pp. 

 811-321, pi. 1, figs. Jf). — It is stated that the object of this article is to suggest 

 " titles and give glimpses into a few of the many stories that are available to 

 those who desire to read them, either in books or in the air itself." It gives a 

 very brief general account of the atmosphere and its circulation ; points out 

 some of the difficulties of studying the subject ; calls attention to some interest- 

 ing facts regarding atmospheric dust and moisture; sets forth the general plan 

 and purpose of weather maps and what they show; and urges the importance 

 of a more general study of the weather by reading and observation. 



Dry fogs and their classification, G. G. Shenbeeg (Trudy. SeWc. Khoz. Met., 

 No. 15 {1915), pp. 162, figs. 5). — Fog is defined as a haziness of the lower atmos- 

 phere decreasing its transparency. Fogs are divided into two classes, (1) damp 

 fogs in which the decreased transparency of the atmosphere is due to minute 

 drops of water or ice crystals and (2) dry fogs caused by scarcely perceptible 

 particles of earth, dust, smoke, ashes, etc. Smoke fogs, ash fogs, dust fogs, 

 optical fogs, and cosmic fogs are described in detail and a classification is pro- 

 posed. 



Monthly Weather Review (V. 8. Mo. Weather Rev., 4i {1916), Nos. 1, pp. 

 1-60+ XVII, pis. 11, figs. 6; 2, pp. 61-110, pis. 11,, figs. 11).— In addition to 

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

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

 and of recent papers on meteorology and seismology ; notes on the weather of 

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

 January and February, 1916; condensed climatological summaries; the usual 

 climatological tables and charts ; and a subject and author index for 1915, these 

 numbers contain the following articles : 



No. 1. — Solar Radiation Measurements at Lincoln, Nebr., 1911-1915, by H. H, 

 Kimball ; Solar Radiation Measurements at Madison, Wis., 1913-1915, by H. H. 

 Kimball and E. R. Miller; Duration of Twilight (reprinted), by H. H. Kim- 

 ball; Lunar Halo of July 24, 1861 (illus.), by W. B. Frew; Wind Velocity and 

 Elevation (illus.), by W. J. Humphreys; Some Researches in the Far Eastern 

 Seasonal Correlations (illus.), by T. Okada ; Annual Hours of Fog, 1885-1915; 

 an abstract of The Physician and the Weather Bureau ( illus. ) , by F. A. Carpen- 

 ter (E. S. R., 34, p. 509) ; and Alto-cumulus with Virgulus, by C. F. Talman, 



No. 2. — Meteor Observations ; Arequipa Pyrheliometry ; Horizontal Rain- 

 bows on Lake Mendota (illus.), by C. Juday ; Halos at Fort Worth, Tex., and 

 Their Relation to the Subsequent Occurrence of Precipitation, by H. H. Mar- 

 tin ; Origin and Maintenance of the Earth's Electric Charge, by W. F. G. 

 Swann; Meteorology of the Moon (illus.), by W. H. Pickering; Agricultural 

 Meteorology, by J. W. Smith (see p. 114) ; Breathing Wells and Pressure 

 Changes ; Alto-cumulus with Virgulus ; Severe Ice Storm in Michigan ; Rela- 

 tion Between Rainfall and Synoptic Winds, by H. H. Clayton; Long-range 

 Forecast of the Winter Minimum Temperature for Hamada, Japan, by M, 



