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ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 



the unaffected spectrum regions in the violet and the red. These 

 facts are illustrated in Figure 2. 



The deviation from the straight-line plots of these energy spectrum 

 ratios becomes, then, a measure of the ozone contents of the higher 



36 32 30 28 26 24 22 20 19 16 



FiGUUjj 2. — Graph for measuring absorption by atmospheric ozone 



atmosphere. The results have been so reduced by us as to give the 

 percentage corrections for ozone absorption to be applied to our 

 solar-constant values on all days of observation at Table Mountain. 

 These corrections apply only to the so-called " short method " of 

 observation. The long method takes cognizance of the ozone absorp- 

 tion in another way. 



By the generosity of a friend of the Institution we are preparing 

 to send an expedition to Table Mountain in September, 1930, to 



Figure 3. — Variations of solar radiation since 1924 



make solar observations there through definite known amounts of 

 ozone, so as independently to standardize this new ozone method. 

 The method is applicable on all days when solar radiation work has 

 ever been done. 



