94 



ILLINOIS ACADEMY OF SCIENCE 



Fig. 1. Graphs showing the evaporation on the prairie, 

 summer 1911. a:. Mean at stations 1 and 2. b: at station 3, 

 cup aljove vegetation, ^^'eekly rain-fall in cm. shovk^n at base 

 of fipfure. 



may be seen that station 3, the one having the cup above the 

 vegetation, gave the same fluctations as did the other sta- 

 tions and dififered only in that the rate for each period was 

 always 25 to 30 per cent greater. 



It may be instructive to compare the results here with 



