SOIL MOISTURE AND TO EVAPORATION. 



29 



fourth, the same in inches. The last three columns give the rainfall, in 

 centimeters and inches, and the average temperature (given in degrees 

 Fahrenheit). The latter was obtained by averaging the readings for 

 the day and night separately and taking the mean of these. 



TABLE V. Evaporation, Precipitation, and Temperatures, Summer o 



It is interesting to note that from July 25 to August 22 the total 

 evaporation was about 2. 33 times the rainfall, notwithstanding the fact 

 that this represents the period of summer rains, and the total rainfall 

 noted is considerably over one-fourth of the average annual precipi- 

 tation here. The latter is 30.10 cm. (11.74 in.), according to Coville 

 and MacDougal (1903, p. 27). 



Observations on the evaporating power of the air can not be made 

 in terms of relative humidity as determined with the psychrometer, 

 for this method, of course, leaves entirely out of account the factor of 

 air currents already mentioned. Perhaps, aside from the evaporimeter 



