SATUEN'S DARK EING. . 105 



SATURN'S DARK RING. 



Mr. Trouvelot, of Cambridge, Mass., has noticed that the inner half of 

 the dark ring is so transparent that the outline can hardly be recognized 

 where it crosses the planet, whereas the outer half is so much more opaque 

 that the outline of the planet can hardly be seen through it. This fact is 

 not only remarkable in itself, but still more remarkable when we remember 

 that until quite recently the character of the dark ring was quite different. 

 The whole width of the ring was formerly uniformly transparent, or at 

 least so nearly so that no difference could be recognized between the outer 

 and inner parts of this ring. This thinning of the inner edge is probably 

 accompanied by a gradual extension of the ring-system toward the planet. 



Clerk Maxwell long since pointed out that a change of this sort was to be 

 expected as a natural consequence of collisions taking place among the tiny 

 moons forming this ring system. And other observations by Mr. Trouvelot 

 shows clearly that multiplied collisions of this sort must continually occur; 

 for he finds that from'^.time to time the dark ring assumes an aspect showing 

 that its substance is agglomerated in clustering masses, through which the 

 light of the planet does not penetrate. How strange are the thoughts sug- 

 gested by such changes! "Within the ring itself what energy of life (so to 

 speak) is indicated by the conflict of satellites! And as regards Saturn 

 himself, does it not appear clear that, while such changes as these are taking 

 place in the nearer portions of his system, he cannot yet be regarded as a 

 completed world? We see nature's hand still at work out yonder, fashion- 

 ing under the very eyes of astronomers the system of a planet once thought 

 to have been formed even earlier than our earth. 



The processes of cosmical development which were formerly so ener- 

 getically disbelieved, but have now taken their place among astronomical 

 probabilities (and almost as certainties), seem here to be. actually in pro- 

 gress. Nature has been detected in the act, and there is good reason for 

 believing now, what was suggested by the present writer eleven years since, 

 that 'in the variations perceptibly proceeding in the Saturnian ring-system 

 a key may one day be found to the law of development under which the so- 

 lar system reached its present condition. — London Spectator. 



From an examination of the observations of the minute star around 

 which Sirius is revolving, Mr. Wilson, of Eugby, concludes that its period 

 of revolution is two hundred years, in an orbit fifty times that of the earth. 

 He also shows that while the sum of the masses of Sirius and its companion 

 is about three times that of the sun, its light, according to the old method 

 of calculation, is more than two hundred times that of the sun. 



