SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 56, NUMBER 19 



THE SILVER DISK PYRHELIOMETER 



(With One Plate) 



BY 



C. G. ABBOT 



Director, Astrophysical Observatory of the Smithsonian Institution 



(Publication 2008) 



CITY OF WASHINGTON 



PUBLISHED BY THE SMITHSONIAN INSTITUTION 



March 31, 1911 



