I 9 2 °] 



FREEMAN— EVAPORATION AND TRANSPIRATION 



197 



r 



Tempera 



ture 



outside 



27.0 

 26.O 

 26.O 



25-9 



27.0 

 26.O 

 26.I 

 26.I 



TABLE I 



Evaporation experiment with atmometer 



Dewpoint Dewpoint 

 outside of escaping 



air 



O 

 O 

 O 

 O 



13.8 

 13.2 



12.8 

 12.8 



Average 







l6. 2 







l6. 2 







15.8 







16.O 



Average 



Evaporating surface 



45 . 8 sq. cm 

 45 . 8 sq. cm 

 45 . 8 sq. cm 

 45.8 sq. cm 



1 

 1 

 1 



1 



75-47 sq 

 75 -.47 s q 

 75-47 sq 

 75-47 sq 



cm. 

 cm. 

 cm. 

 cm. 



1.645 



1645 



1645 

 1645 



Found 



y 



13.8 

 13.2 



12.8 

 12.8 



13.2 



16.2 

 16.2 



15.8 



16.0 



16. 1 



Calculated 



y 



13-5 

 13.0 



13.0 

 I3-0 



I3-I 



16.8 



l6. 2 

 l6. 2 

 l6. 2 



l6.4 



Difference 



-0-3 

 — o. 2 



+0.2 

 +0.2 



O.I 



+0.6 



o 



+0.4 



+0. 2 



+O.3 



is here used as unity. The other constants were as follows: 

 c = 1.257, = 42.04 sq. cm., here taken as unity, and a 1 = ys-47 

 sq. cm. = i .7954. 



There remains to show the details of an experiment in which 

 both the area and wind movement were varied. Here a = 52. 98 



Tempera- 

 ture 



outside 



21.7 



2I -5 



21. 2 



2I.O 



20.9 



20.8 



20.8 



20.7 



20.7 



20.7 



21.7 



21.6 



21.4 



2I.O 



2I.O 



TABLE II 



Evaporation experiment with atmometer 



Dewpoint 

 outside 



Dewpoint 



of escaping 



air 



I 

 I 



I 

 I 

 I 



I 

 I 



2 

 2 



2 



O 

 O 

 O 

 O 

 I 

 I 

 2 

 2 



3 

 2 



IO.6 

 I0.2 

 IO. O 

 IO.4 

 IO. O 

 IO. I 

 IO. 2 

 II. 2 



I0.5 

 9.8 



Average 





Average 



Evaporating surface 



I 

 I 

 I 

 I 

 I 



7954 

 7954 

 7954 

 7954 

 7954 



Found 



y 



9.6 

 9.2 

 9.0 



9-4 

 8.9 



9.0 



9.0 



9.0 



8.2 



7.6 



Calculated 



y 



9.2 

 9.1 



8.9 

 8.9 



8.8 



8.7 



8-7 

 8.2 



8.1 

 7.6 



8.9 



8.6 



" 



11. 4 



ix. S 



11. 2 



11. 4 



ii-3 



11. 2 



10.5 



11. 



10.6 



11. 1 



11. 



11. 2 



Difference 



0.3 



+0.2 



