THE WATER OF SOILS. 



255 



SUMMARY OF AVERAGE WEEKLY LOSSES BY EVAPORATION, WITH VARYING TEM- 

 PERATURES OF WATER, AT BERKELEY, CAL., IN JULY AND AUGUST, 1904. 



Temperature of water. 



Degrees Fahrenheit : 



55-5 



62.0 , 



69.2 



80. i 



89-2 



Weekly 

 evapora- 

 tion. 



Inches. 

 0.42 

 0.77 



i-54 



3.08 



3-92 



A farther illustration is given in the subjoined table, show- 

 ing maxima and mimima of monthly evaporation, as well the 

 totals of one (seasonal) year, in three California localities 

 where the air-saturation is considerably below that at Berkeley, 

 ranging in summer from 50% to 20% and even less (at 

 Calexico in the Colorado desert) : 



SUMMARY OF EVAPORATION-LOSSES FROM WATER-SURFACES, AT POMONA, TULARE, 

 AND CALEXICO, CAL., FROM JULY I, 1903, TO JULY 31, 1904. 



Of these three stations, Pomona is located within reach of 

 the ocean winds, but distant 25 to 30 miles from the shore. 

 Tulare is situated in the upper San Joaquin valley, far in the 

 interior; Calexico is in the southern part of the Colorado 

 desert, with extremes of temperature ranging from 13 Fahr. 

 in winter to 120 in summer. 



Evaporation in Different Climates. The following table 

 conveys some general data regarding average evaporation from 

 water-surfaces in different climates. Evaporation from the 

 soil-surface depends largely, of course, upon the mechanical 

 condition of the surface, the extent to which it is wetted, and 



