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BULLETIN 700, U. S. DEPARTMENT OF AGRICULTURE. 



orating instruments which might also furnish data on sunshine 

 intensity, the evaporation data front the white and black spherical 

 atmometers have been used in connection with the plant studies. 



FIG. 9. Summation of evaporation from black and white spheres and the difference 

 between them. Record made during growth studies. Started late. 



BAROMETRIC PRESSURE. 



The barometric pressure was measured by aneroid barometers. The 

 instruments were standardized from time to time at the central sta- 

 tion, where the elevation and pressure were known. 



