366 COSMIC PHILOSOPHY. [pt. ii. 



the angular velocities of the inner and outer surfaces re- 

 spectively will he nearly equal, and the planetary mass into 

 which such a hoop concentrates will have its greatest diameter 

 at right angles (or nearly so) to the plane of its orbit ; so 

 that its tendency to rotate in the line of its revolution will 

 be so slight as to be easily overcome by any one of a hundred 

 possible disturbing circumstances. Without feeling required 

 to point out the precise nature of such circumstances, we 

 may readily see that, in the case of the outermost planets, 

 the causes which ordinarily make the rotation coincide with 

 the line of revolution were at their minimum of efficiency. 

 So that the retrograde rotation of Uranus, though not perhaps 

 actually implied by the hooped shape of its ancestral ring, 

 is at any rate quite in accordance with it. 



I cite this example, not merely on its own account, but 

 also by reason of the further disclosures to which it leads us. 

 Whatever may be thought of the special interpretation just 

 cited, there is no doubt that Mr. Spencer's conception of 

 hoop-shaped and quoit-shaped rings points to a notable series 

 of harmonies among the phenomena of the solar system. 

 Observe, first, that according to the theory, the outer planets 

 ought in general to be much larger than the inner planets ; 

 and for a very simple reason. The ancestral rings which 

 coincided with the immense orbits of Uranus and Neptune 

 must of course have been larger than the ancestral rings 

 which coincided with the smaller orbits of Mars and the 

 earth. A ring, for example, which is seventeen thousand 

 millions of miles in circumference may be expected to con- 

 tain more matter than a ring which is less than six hundred 

 millions of miles in circumference; and hence we may 

 understand why Neptune contains at least sixteen times as 

 much matter as the earth. 



But this, though significant, is not a complete explanation ; 

 for as the case now stands, it would seem as if there ought 

 to be a regular gradation in the sizes of the planets. Hot 



