SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 87, NUMBER 9 



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IRoeblino 3Funb( may 24 1932 



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PERIODICITY IN SOLAR VARIATION 



(With Two Plates) 



BY 

 G. G. ABBOT 



Secretary, Smitlisonian Institution 



AND 



GLADYS T. BOND 



Statistical Assistant, Smithsonian Astrophysical Observatory 



(Publication 3172) 



CITY OF WASHINGTON 



PUBLISHED BY THE SMITHSONIAN INSTITUTION 



MAY 24, 1932 



