METEOEOLOGY WATER. 417 



range for July 18.5°. Temperatni*es of 100° or over have been recorded at most 

 stations in all the summer months. 



" On the other hand, most of the stations have a record of freezing tem- 

 perature during this season. The highest summer temperature on record is 

 116° at St. George in June, while the lowest is 20° at Richfield, in the same 

 month. The average date of first killing frost in autumn varies from Sep- 

 tember 2 at Heber to October 28 at Hite, while the earliest date on which 

 frost ever occurred in autumn is August 11 at Heber. The average date of 

 last killing frost in spring varies from April 11 at Hite to June 14 at Heber, 

 while the latest date on which killing frost ever occurred in spring was July 

 30 at Heber." 



The precipitation for the State averages about 11 in., being about IS in. in 

 the northern and 6 in. in the southern portion. Locally the precipitation 

 varies from 5.4.3 in. at Green River, to 24.36 in. at Ranch, Kane County. As 

 a rule, the heaviest precipitation occurs in the central portion of the State. 

 The largest amounts fall in winter and spring, and the least in June and 

 October. There are about 50 rainy days in the year. Locally the rainy days 

 vary from 22 at Green River to 89 at Salt Lake City." 



Notes on evaporation in 1911, L. Dumas (Ann. GemMoux, 22 (1912), No. 1, 

 pp. 12-32). — Observations during August and October, 1911, on evaporation 

 from ordinary cylindrical drinking glasses placed 0.15 meter and 2 meters 

 above the ground are reported. 



Discussing the results, it is shown that the amount of evaixtration is the 

 resultant of numerous accelerating and retarding factors. Among the first 

 are wind, heat, solar attraction, extension of the superficial area, and low 

 barometric pressure. Among the factors which retard evaporation are oily 

 substances, the mass of the liquid, salt content, cloudiness, lowering of the 

 level of the water, and aeration or the solution of gases. The combination of 

 such diverse causes renders superficial observations on evaporation very con- 

 tradictory. During the summer of 1911, which was unusually hot and dry, 

 there was appreciable evaporation during the night. With the lowering of 

 temperature, however, evaporation ceased and there was even a slight gain 

 in some cases due to condensation of moisture from the air on the sides of 

 the glasses. 



The effect of subsoil water on the cotton crop, W. L. Balls (Yearbook 

 Khedrv. Agr. Soc. Cairo, 1909, 8up., pp. 24). — This is a brief summary o:^ 

 present information concerning the rise of the water level and its effect on the 

 cotton crop in Egypt. 



It is believed that the water table is the main factor in the decrease of the 

 cotton crop and that the rise in water level probably causes boll shedding, a 

 phenomenon which is presumed to be " of great economic importance in its 

 effect on the yield of the crop." The author makes suggestions to growers 

 for conducting and reporting observations on water level, soil texture, and 

 boll shedding, and emphasizes the need of systematic studies of the problem. 



An appendix contains a note on a method of taking water levels by F. Hughes 

 in which brief directions are given for determining the nature of the subsoil 

 and water conditions. 



Mississippi River levees and their effect on river stag'es during flood 

 periods, S. C. Emeby (U. 8. Dept. Agr., Weather Bur. Bui. 38, pp. 21). — This 

 paper describes the levee and jetty systems of the Mississippi River, and dis- 

 cusses their effect in raising the flood levels of the river and increasing the 

 depth and extending the area but shortening the period of flooding of the 

 adjacent lands. 



