

1920] 



FREEMAN— EVAPORATION AM) TRANSPI RATIOS 



193 



be a constant linear proportion of the rise of /. A number of other 

 experiments were made which exhibited a similar agreement 

 between the experimental and calculated results. All of these 



1 



i 3 4 5 t 7 % 1 10 It tl 13 1+ IS 'C. 



Fig. 2 



are summarized in fig. 2, in which the ascending line oy represents 

 the calculated value of y % while the dots show the experimental 

 results obtained. 



Effect of wind movement 



It has been stated that the value of z depends upon the rate of 

 air movement (w) and the extent and nature of the evaporating 

 surface. When the latter remains unchanged and only wind move- 



; , in which c and n 



form 



1 



i+c(w) 



are constants. 



this formula 

 fig. 3; ot is t 



formula 



t-h 



i+c(w) 



In using 



which 



and 



! is its dewpoint; 



1 . 8° respectively. 

 The rate of wind movement may be plotted along o 1 t tJ from which 

 the found values of y may be plotted as orriinates. The curved 

 line ov ioininz these ordinates then gives the value of y, which is 



