172 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



4- -3 -2 



1 1- 



20H 



10 







20 

 



50- 



50 



e 



o 

 E 



50- 



1 



Magnitudes absolues 

 1 3 4 5 6 8 9 



10 11 



* t_ 



SO- 



■H 1 1 1- 



Type B 

 33 ELoilss 



Type A 

 135 Etoiles 



■ -«- -.■* 



Type F 



300 Etoiles 



Type G 

 507 Etoiles 



Type r\ . avarice 



<!<4.K 9 ) 



204 Etoiles 



••*- -3 -2 -1 



12 3 4-56 



Magnitudes absolues 



10 n 



Fia. 1. — Curves showing the distribution of absolute magnitudes among the different 



spectrum classes. 



The abscissae show the absolute magnitudes, reduced to a distance of 10 parsecs (34 

 light years) ; the ordinates give the corresponding number of stars, each point correspond- 

 ing to an interval of half a magnitude. 



