304 DISCUSSIONS IN COSMOLOGY. 



It would be the suddenness and almost instantaneity 

 with which the mass would receive the entire store of 

 energy, before it had time even to assume the molten, 

 far less the gaseous condition, which would lead to 

 such fearful explosions and dispersion of the materials. 

 If the heat had been gradually applied, no explosions, 

 and consequently no dispersion, of the materials would 

 have taken place. There would first have been a 

 gradual melting ; and then the mass would pass by 

 slow degrees into vapour, after which the vapour 

 would rise in temperature as the heat continued, until 

 it became possessed of the entire amount. But the 

 space thus occupied by the gaseous mass would neces- 

 sarily be very much smaller than in the case we have 

 been considering, where the shattered materials were 

 first dispersed into space before the gaseous condition 

 was assumed. 



Reason why Nebulce are of such various Shapes. — 

 The latter theory accounts also for the various and 

 irregular shapes assumed by the nebulae ; for although 

 the dispersion of the materials would be in all direc- 

 tions, it would, according to the law of chances, very 

 rarely take place uniformly in all directions. There 

 would generally be a greater amount of dispersion in 

 certain directions, and the materials would thus be 

 carried along various lines and to diverse distances ; 

 and although gravity would tend to bring the widely 

 scattered materials ultimately together into one or 

 more spherical masses, yet, owing to the exceedingly 

 rarified condition of the gaseous mass, the nebulae- 

 would change form but slowly. 



Reason why Nebulce emit such feeble Light. — The 

 feeble light emitted by nebulae follows as a necessary 

 result from the theory. The light of nebulae is mainly 

 derived from glowing hydrogen and nitrogen in a 



