26 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8 1 



]Mean intensity 



m 



Before sumniariziniL;' the re.sult.s of this paper, the writer wishes 

 to express his appreciation of the criticisms of Dr. Abbot, and the 

 aid furnished by Miss Margaret Marsden and Mr. Hugh Freeman 

 in the many coiuputations, as well as his indebtedness to the workers 

 in the field whose observations made possible this discussion. 



SUMMARY 



The amoinit of energy absorbed from the incoming solar radiation 

 by the yellow ozone band has been used to measure the variations in 

 the amount of atmospheric ozone during the years from 1921 to 

 1928. These observations have been made in both the northern and 

 the southern hemispheres. 



The resulting values show a distinct yearly march in both hemi- 

 spheres. In the northern hemisphere the maxima of this march occur 

 between April and May, the minima between August and November ; 

 in the southern hemisphere the maxima occur between August and 

 September, the minima between April and May. In other words in 

 both hemispheres the maxima occur in the spring, the minima in the 

 autumn. 



In the northern hemisphere a marked relationship exists between 

 the ozone and the Wolfer sun-spot numbers. The range in the monthly 

 mean values for the ozone numbers is great and between 20Xio~* 

 and 100 X lO"^ calories absorbed per cm.- per minute from the incom- 

 ing solar energy. 



