110 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1923 



curve confirm the similar work of 1920, and lead to a revision of the 

 results of earlier work published in Volumes III and IV of the 

 Observatory Annals. Energy spectra of 10 of the brighter stars 

 were observed at the focus of the 100-inch telescope on Mount Wil- 

 son by means of a special spectrobolometric apparatus. Tempera- 

 ture differences of approximately one one-hundred-millionth of a 

 degree centigrade were measured in this investigation. Solar radia- 

 tion outfits have been prepared for Australia and Argentina, to be 

 installed in the year 1923. 



Respectfully submitted. 



C. G. Abbot, Director. 



Dr. Charles D. Walcott, 



Secretary/, Smithsonian Institution. 



