IQ2o] 



FREEMAN— EVAPORATION AND TRANSPIRATION 



195 





I 



locate the point c with reasonable accuracy. When only two or 

 three points are known, however, the second method should be 



used. 



pe 



ement 



5.706 and 0.5 respectively. With these data the complete theo- 

 retical curve oy may be calculated and plotted, and the provisional 

 curve used in finding the point c corrected and extended. 



.*/ X>10 .0300* &SO .QLQ &70.(fi0 j9 J06 .110 JiO .130 J HC .150 jui ./70 JM .W Co.. It aU ftA. m-*&. 



Fig. 4 



In fig. 3 the complete curve given is the calculated theoretical 

 curve, and the dots show the close adaptation of the experimental 

 data to it. The agreement appears almost strikingly complete. 



experiment 

 figure the 



0.58 



and c = 2 . In this 

 scale than in fig. 3. As will be seen later, the factor c includes 

 both the corrections for the area and the nature of the evaporat- 

 ing surface, and to adjust the temperature and wind movement 

 factors to each other. The correspondence of the experimental 

 results with the theoretical curve is again quite close, as is shown 



by the dots. 



It now remains to determine the influence of changes in the 

 area of the evaporating surface, assuming that its character 

 remains constant. Changes in the evaporating area will affect 

 both c and n. As the area at which c is determined rises, the value 



