214 



CHARLES A. SHULL 



evaporation stations have not undertaken hygrometric measure- 

 ments, so that this third important factor in evaporation rates, 

 relative humidity, cannot be treated statistically. 



The mean daily atmospheric movement for the 524 days of 

 observation is 98.57 ± 1.99 miles, the mean daily temperature 

 65.06° ± 0.45°, and the mean daily evaporation 0.2376 ± 0.004. 

 The correlation table for air flow and evaporation is shown in 

 table 2. 



TABLE 3 



Correlation between temperature and evaporation 

 Average daily temperature — > 



The standard deviation, <r, of wind flow is 67.7 ± 1.42 miles, 

 and of evaporation, 0.1368 ± 0.0029 inch. By the usual meth- 

 ods of determining degree of correlation, it is found that the 

 correlation coefficient for air movement and evaporation is 

 0.29 ± 0.027. 



The distribution of evaporation with respect to temperature is 

 shown in table 3. 



