SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 87, NUMBER 9 



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PERIODICITY IN SOLAR VARIATION 



(With Two Plates) 



BY 

 C. G. ABBOT 



Secretary, Smithsonian Institution 



AND 



GLADYS T. BOND 



Statistical Assistant, Smithsonian Astrophysical Observatory 



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(Publication 3172) 



CITY OF WASHINGTON 



PUBLISHED BY THE SMITHSONIAN INSTITUTION 



MAY 24, 1932 



