F. W. Very — A Cosmic Cycle. 103 



also such close binaries as ft Lyrae, in which the separation of 

 the components by excessively rapid rotation, or possibly by 

 rotation and explosion combined, is barely effected. 



The evolution of negative hydrogen still continues in our 

 sun ; but in the stars of Secchi's third type (McClean's Div. 

 5) — the long-period variables — positively electrified hydrogen 

 is found whenever bright lines occur. The increasing absorp- 

 tion and its banded character (pointing to molecular complex- 

 ity), together with the diminished intensity of the shorter 

 waves, indicate that the third-type stars have begun to wane. 



Some of the characteristics of stellar childhood recur in old 

 age, but others are entirely different, or even opposite. 



Passing from the evidence furnished simply by the light of 

 the stars to that afforded by their consociations, I proceed to 

 apply the theory to the phenomena of binary stars. 



Of eighteen stars having spectra of composite type, given 

 by. Miss Maury," the majority have the brighter star of solar 

 type. Holdenf finds that among undoubted binaries having 

 components of unequal magnitude, the brighter is usually a 

 yellow, and hence presumably a solar star, while the fainter is 

 a blue or purple, and therefore probably a Sirian star ; but 

 some remarkable exceptions exist, and such stars as Siriits and 

 Procyon prove that no simple rule, depending on rates of 

 cooling as affected by mass alone, can cover all of these cases. 

 This diversity of development in the members of a pair 

 appears to show that, in the first place, fission has occurred 

 after heterogeneity had been established ; and, second, that 

 sometimes the larger star retains the greater part of the sub- 

 stances which go to make up a solar star, while in other cases 

 it is the smaller star which has received the denser central 

 parts of the composite mass.;): This difference of composition 

 must dominate all subsequent evolution. 



While heavy materials may be ejected by long-continued 

 explosions of minor intensity from the central into an outer 

 shell, the lighter substances of the outer layers are not carried 

 downward in any corresponding degree. Hence in the sepa- 

 ration into a binary, the body composed mainly of deeper sub 

 stances has been largely freed from explosive material, and is 

 ready to enter upon the more quiescent existence of a solar 

 star ; while the companion, consisting principally of material 



* Miss Antonia C. Maury, Ann. Harvard Coll. Obs., vol. xxviii, pt. 1, p. 92, 1897. 



f E. S. Holden, '-Note on a Belation between the Colors and Magnitudes of the 

 Components of Binary Stars," this Journal (3), vol. xix. p. 467. 1880. Professor 

 Holden finds that when binary stars have both members of the same color, the mean 

 difference of magnitude is: B — A=-0 - 53 mag; when of different colors, B — A= 

 2*4:4 mag. ;- We do not find isolated stars of decided green, blue or purple 

 colors " (p. 468); but contrast tends to an exaggerated estimate of color. 



\ See, however, the suggestion concerning the development of the Algol binaries 

 on p. 105. 



