158 



HOWARD E. PULLING 



about 1.8 to about 2.0 have been recorded almost every year. 

 "No regular periodicity seems to appear, but the values often 

 range from low to high and return within seven to ten days. 

 The range frequently reaches 5%." n Although the averages 

 for the summers during which measurements were made agree 

 very closely with each other, as table 1 indicates, the total 

 range of fluctuation (from about 1.81 to about 2.04) is approxi- 

 mately 12% of the "mean solar constant" given above. 



Solar constant values. 



TABLE 1 



Summary: 1902-1912. Ann. Astrophys. Obs. Smithsonian 

 Inst., table U, V- 1U, vol. 8, 1913 



* This value becomes 1.923 if the results are changed in a manner that the au- 

 thors believe advisable. 



Regarding the changes in the form of the solar energy curve 

 little can be said at present. The evidence seems to point 

 to a variability in the shorter waves that is proportionally 

 greater than for longer waves. 12 This may be seen by comparing 

 the ordinates of figure 2 with those of figure 4, the maximum 

 in the former case falling at wave length 0.47m and in the latter 

 case at about 0.4()ti. 



11 Ann. Astrophys. Obs. Smithsonian Inst. 3: 119. 1913. 



12 Ann Astrophys. Obs. Smithsonian. Inst. 3: 131-133. 1913. 



