THE AUTHOR'S THEORIES OUTLINED 61 



Granting my contentions that gravitational self -com- 

 pression perpetually generates heat, and that all sub- 

 stances are susceptible to explosion under adequate 

 pressures, it follows : 



1. That Class B stars (assuming these to be the 

 most massive) are the hottest of all. 



2. This being the case, the central gaseous chamber 

 must be greatly enlarged and the shell correspondingly 

 thinned, (1) by the enhancement of the temperature and 

 consequent, intensified buoyancy of the imprisoned gases, 

 (2) by the distillation of a maximum number of elements 

 and compounds out of the shell, and (3) by the extension 

 of the superficial area over which the magma of the 

 residual shell has to be distributed. 



3. Not only, however, is the shell relatively thinned 

 in the sense of linear measurement, it is also rendered 

 thinner in the matter of consistency, for the vastly 

 augmented temperature fuses all of its component sub- 

 stances until they flow like molten steel from a blast fur- 

 nace. 



4. Now, it is common knowledge that the more re- 

 fractory to volatilization a mineral substance is, the 

 hotter and brighter it is when raised to incandescence; 

 and there are degrees even to this state of incandescence, 

 comparatively small increases of temperature returning 

 truly amazing rewards in the way of enhanced illumina- 

 tion. 



5. As our giant B star grows larger and larger, its 

 shell becomes thinner in consistency, and thinner and 

 thinner dimensionally (at least relatively to its diam- 

 eter), thereby rendering it thermally unstable and its 

 tenure of life insecure. Eventually the equilibrium be- 

 tween the internal buoyancy on the one hand and the 

 weight and cohesion of the shell on the other is overcome 

 by the former, the shell suffers rupture, and its substance 

 is spattered to great distances, giving rise to a nebula 

 of great size. Nebulae thus produced are apt to be 



