SCENES ON THE PLANETS. 345 



dust, through which run immense waves, condensation and rare- 

 faction succeeding one another as in the undulations of sound. 

 Yet, with all their inferential tumult, they may actually be as 

 soundless as the depths of interstellar space, for Struve has shown 

 that those spectacular rings possess no appreciable mass, and, 

 viewed from Saturn itself, their (to us) gorgeous seeming bow may 

 appear only as a wreath of shimmering vapor spanning the sky and 

 paled by the rivalry of the brighter stars. 



In view of the theory of tidal action disrupting a satellite with- 

 in a critical distance from the center of its primary, the thought- 

 ful observer of Saturn will find himself wondering what may have 

 been the origin of the rings. The critical distance referred to, and 

 which is known as Roche's limit, lies, according to the most trust- 

 worthy estimates, just outside the outermost edge of the rings. 

 It follows that if the matter composing the rings were collected 

 into a single body that body would inevitably be torn to pieces and 

 scattered into rings; and so, too, if instead of one there were sev- 

 eral or many bodies of considerable size occupying the place of 

 the rings, all of these bodies would be disrupted and scattered. If 

 one of the present moons of Saturn — for instance, Mimas, the in- 

 nermost hitherto discovered — should wander within the magic cir- 

 cle of Roche's limit it wpuld suffer a similar fate, and its particles 

 would be disseminated among the rings. One can hardly help 

 wondering whether the rings have originated from the demolition 

 of satellites — Saturn devouring his children, as the ancient myths 

 represent, and encircling himself, amid the fury of destruction, 

 with the dust of his disintegrated victims. At any rate, the ama- 

 teur student of Saturn will find in the revelations of his telescope 

 the inspirations of poetry as well as those of science, and the bent 

 of his mind will determine which he shall follow. 



Professor Pickering's discovery of a ninth satellite of Saturn, 

 situated at the great distance of nearly eight million miles from 

 the planet, serves to call attention to the vastness of the " sphere 

 of activity " ov«r which the ringed planet reigns. Surprising as 

 the distance of the new satellite appears when compared with that 

 of our moon, it is yet far from the limit where Saturn's control 

 ceases and that of the sun becomes predominant. That limit, ac- 

 cording to Prof. Asaph Hall's calculation, is nearly 30,000,000 miles 

 from Saturn's center, while if our moon were removed to a dis- 

 tance a little exceeding 500,000 miles the earth would be in dan- 

 ger of losing its satellite through the elopement of Artemis with 

 Apollo. 



Although, as already remarked, the satellites of Saturn are not 

 especially interesting to the amateur telescopist, yet it may be well 



