316 



L. A. GIDDINGS 



TABLE 4 

 The rates of water loss of Silphium (in grams), and of evaporation from Piche 

 evaporime*ers (in cubic inches) at different wind velocities, together with the tem- 

 perature (Fahr.) and relat ve humid ty. July 8, 1911 



placed in bottles of water which were carefully sealed, and the 

 loss determined by weighirg. 



In the graphs for these experiments the curves for the leaves 

 and evaporimeters are numbered in the order of distance from 

 the fan. The temperatuie and relative humidity were those of 

 the laboiatory and not for any one of the positions occupied by 

 the leaves and evaporimeteis (fg. 3, fg. 4). 



In table 5 are given the totals for three other experiments. 

 From these data it is evident that there is a close relation between 



TABLE 5 



The relation of unnd velocity {in miles per hour) to the transpiration of Silphium 

 {in grams) and to the evaporation {in cubic inches). 1911 



