46 



THE WONDERS OF GEOLOGY. 



Lect. I. 



ever, could not take place unless the annular band were of 

 uniform composition, which would rarely be the case; 



Ligx. (5. — Telescopic view of saturn. 



hence the ring would most generally divide into several 

 portions, which might sometimes be of nearly equal bulk, 

 as in the Asteroids, while in others they might coalesce into 

 a single mass. The solar nebula?, thus separated at various 

 periods, and constituting planets in a gaseous state, would 

 necessarily have a rotatory motion, and revolve in varying 

 orbits around the central nucleus ; and as refrigeration and 

 consolidation proceeded, each body might project entire 

 annuli or rings, and satellites, in like manner as the sun 

 had thrown off the planets themselves. 



In addition to the appearance of various states of attenu- 

 ation and of solidity presented by the nebulas, the orbs of 

 our own system afford evidence of corresponding gradations 

 of density. The planets near to the sun are denser than 

 those which are more distant : thus Mercury, which is the 

 nearest, is the heaviest, being almost thrice as dense as the 

 earth ; while the density of Jupiter, which is far removed, 



