586 
Journal of Agricultural Research 
Vol. V, No. 14 
the transpiration graphs for a number of clear days sufficient to eliminate 
or minimize the accidental features. In the same manner a composite 
graph for the corresponding days can be prepared for each of the cyclic 
environmental factors—radiation, temperature, and wet-bulb depression. 
The evaporation data have also been combined in the same way. This 
procedure is not adapted to factors which are essentially noncyclic in 
character. Wind velocity, for example, is essentially cyclic in some 
regions and noncyclic in others. While the wind at Akron gives evidence 
of a daily periodicity, the cyclic character is not sufficiently developed to 
give the composite graph much weight. The discussion is not, however, 
limited to the composite values, the hourly values of the transpiration 
and of each environmental factor being given in the tables for each day 
considered. 
WHEAT 
The data obtained for the transpiration of wheat (Triticum spp.) on 
clear days in 1912 are given in Table I, and the environmental data for 
the corresponding period, including solar radiation, air temperature, 
and wind velocity in Tables II, III, and IV, respectively. 
