PLANETARY RINGS AND NEW STARS. 467 



tronoraers to absurd and discordant conclusions in regard to the gen- 

 eral movements and the stability of the rings. 



With the resources which spectrum analysis has conferred on sci- 

 ence, more advantages are to be expected from inquiries in regard to 

 the exact nature of the matter of distant space; and the basis for opin- 

 ions or conclusions in regard to the composition of celestial objects 

 is more then usually favorable in the case of Saturn's bright rings. 

 That they are not entirely liquid or gaseous is evident from their ser- 

 rated edges shown in the observations of Trouvelot, and from the pecu- 

 liar character of the inequalities observed during their disappearance 

 by Lassell and other astronomers. And yet there are few solid sub- 

 stances which could endure the long course of turmoil and ruin without 

 being reduced to powder, and thus rendered incapable of raising moun- 

 tainous structures high enough to be visible from our earth. But if 

 the great annular appendage were largely or wholly composed of water 

 with a temperature near 32° Fahr., the readiness of the fluid to assume 

 a frozen condition would be a remedy to the ceaseless work of destruc- 

 tion, and would give solidity enough to enable incipient satellites to 

 rise to the height of more than one hundred miles before tumbling to 

 pieces. 



The range of temperature necessary for the continuance of such 

 operations must be maintained chiefly by the thermal effects with 

 which they are attended. Any large stock of primitive heat which 

 (according to the more generally received opinions) the rings might 

 have possessed at their origin, must have been long since wasted by 

 radiation from their extensive surfaces. In that remote and frio-id zone 

 of our planetary domain, the rays of our sun are too feeble to mitigate 

 the rigors of extreme cold ; and the outer ring at least can obtain but 

 little calorific relief from the great planet which it environs. But, from 

 the incessant changes and convulsions in the restless fields of matter, 

 heat is abundantly produced by the violent mechanical action which, in 

 a ring of aqueous composition, would proceed in a manner calculated to 

 give a uniformity of temperature. If such a half-frozen ocean were 

 abnormally heated throughout much of its vast expanse, so that a large 

 portion of its ice were liquefied, the water, on obtaining a preponderance, 

 would perform its movements and fluctuations with less violence and 

 loss of living force. The heat produced mechanically would be then 

 less than the amount lost by radiation, and a return of cold would again 

 give ice the ascendancy. Yet, as the temperature declined and the 

 freezing extended, mechanical violence would again become more ener- 

 getic ; and heat would be more copiously developed by the collisions of 

 icy blocks, and by the rise and fall of gigantic mountains. 



Reasoning from the most reliable principles of physics, and guided 

 by the light of recent discoveries, many eminent scientists have come to 

 the very just conclusion that the movement in Saturn's rings must be 

 attended with a loss of energy and a reduction in the size of the orbits 



