18 



BULLETIN 700, U. S. DEPARTMENT OF AGRICULTURE. 



mercury thermometers and exposed in shelters of the Weather 

 Bureau pattern 4J feet from the ground. 



PRECIPITATION. 



The precipitation record was obtained by means of automatic 

 tipping bucket rain gauges, the data from which were harmonized 



/ 23^,56 769 



27 28 29 3O 3/ 



AUGUST 1916 



White sphere 



Free wafer surface 



> Daily m ean temperature 



FIG. 6. Evaporation from white sphere and from free water surface compared with daily 



mean temperature. 



with standard rain gauges. In this way reliable data were obtained 

 as to the amount and rapidity of the rainfall. 



EVAPORATION. 



The evaporation was recorded in two ways: (1) By means of the 

 standardized porous cylindrical and spherical atmometers, and (2) 

 by means of a free water surface. 



In the case of the porous spheres, both the black or radio cup and 

 the white cup were used at each station. The spherical, as well as the 

 white cylinder cups, were fitted with rain-correcting apparatus and 



