96 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1944 
A major part of Dr. Abbot’s work has consisted in the study of 
solar-constant variation and associated solar changes in connection 
with the weather. A paper entitled “Weather Predetermined by Solar 
Variation” has resulted, and appeared just at the close of the fiscal 
year. In the course of these studies it was found that variations of 
the areas of clouds of calcium vapor (calcium flocculi) as photographed 
at the Spanish Observatory of Ebro since 1910 were associated in the 
same way as solar-constant changes in predetermining the weather. 
This led to an attempt to weaken the light of the sun’s disk by excessive 
spectral dispersion so far as to make visible variations of the bright 
lines of hydrogen or helium in the chromosphere. Doubtful evidences 
of such chromospheric lines were indeed recorded, but though the 
dispersion of the third order of a grating of 15,000 lines to the inch, a 
battery of prisms, and a path of 55 meters of travel of the spectrum 
rays were employed, the photospheric spectrum was still too bright 
to disclose plainly the chromospheric lines or their variation. 
’ 
DIVISION OF RADIATION AND ORGANISMS 
As in the preceding year the work of this Division was mainly 
concerned with secret problems relating to the war. However, a 
paper entitled “The Influence of Light and of Carbon Dioxide on the 
Respiration of Etiolated Barley Seedlings” was prepared and 
published by Drs. Weintraub and Johnston. 
Respectfully submitted. 
C. G. Axzor, 
Director. 
Tue SECRETARY, 
Smithsonian Institution. 
