STUDIES IN STELLAR STATISTICS. II. 25 
The considerable decrease of R with increasing M, which was 
found when all stars of type B were taken together is, with one ex- 
ception, no longer exhibited. On the other hand the different subclas- 
ses possess a pronounced variation of luminosity. Using the results 
obtained from all stars brighter than the 6" magnitude, we have 
Subclass Bo: R=2.67, M=— 2™13 , 
> Bi: R=T.36 , M = — 4.33 
» Bas met. Mets 
» Bs: R=3.42, M= — 2.67 
» DR das, M= 2. 
The mean errors in R as well as in M may be estimated at 
some tenths of the units used. 
The subclasses B: and Be possess the greatest luminosity, the 
stars of this classes having an absolute magnitude equal to — 4".3s 
and ZA — 7.36. The other subclasses Bo, Bs and Bs have, approxi- 
mately, the same absolute magnitude = — 2".6 and the same R = 34. 
The variation of R with m, when all classes were taken toge- 
ther, thus finds a natural explanation. We find indeed from Table 2 
that of the brighter stars there are 27?/o belonging to the subclasses 
b: and Be, whereas there are only 11°/o such stars among the stars 
fainter than the 5, but brighter than the 6", magnitude. 
The order of evolution 
Joa I. Ja, ABH Joe 
indicated by the Harvard classification is not confirmed by this in- 
vestigation. The order ought rather to be: 
Bite 159 5 IBS oo, Tor 
From the description given in the Harvard Annals there seems 
also to be a support for this, or a similar, order of the subclasses, as 
the subclass B2 is described as that one where the lines due to he- 
lium reach their maximum intensity. 
In the subclass Bo there seems to be a great difference be- 
tween the luminosities of the stars of different apparent magnitudes, 
the bright stars giving R = 12.51, the fainter ones R= 1.7. I have 
Nova Acta Reg. Soc. Sc. Ups. Ser. 4, Vol. 4, N. 7. Impr. 1%/e 1916. 4 
