628 
Journal of Agricultural Research 
Vol. V f No. 14 
also been expressed in terms of percentage of the maximum. In the case 
of temperature and wet-bulb depression, the calculation has been based on 
the maximum range—i. e., the mean minimum is taken as zero on the 
scale. The data for the various crops reduced to this uniform basis are 
presented in figures 9 to 15, inclusive, the axis of abscissas representing 
time and the axis of ordinates the percentage of the mean daily maximum 
(or mean daily range). 
Fig. 9.—Graphs showing transpiration of wheat and the hourly values of cyclic environmental factors, all 
plotted in percentage of the maximum or maximum range. 
Fig. 10.—Graphs showing the hourly transpiration of oats and the hourly values of the cyclic environmental 
factors, all plotted in percentage of the maximum or maximum range. 
Fig. x 1 .—Graphs showing the hourly transpiration of sorghum and the hourly values of cyclic environmental 
factors, all plotted in percentage of the maximum or maximum range. 
An inspection of the charts will show that the radiation graph rises in 
advance of the other cyclic environmental factors. This is to be expected, 
since the change in radiation is the primary cause of the cyclic change 
of the other components. For the same reason the radiation also rises 
in advance of the transpiration and falls either in advance of it, as in 
