THE PLANET SATURN. 359 



ever, we never yet have caught a glimpse, so far as known, of the 

 real surface, whatever that surface may be. The rolling cloud 

 masses completely envelop the planet and shut it out entirely 

 from the sun's light. 



We can scarcely suppose, then, that these clouds are raised 

 upon this distant world by the solar heat, especially when we see 

 how feeble that heat is compared with what the earth receives. 

 And this is but another argument to prove the theory of Saturn's 

 present condition as already given, for it is most probable that 

 the planet holds in its own vast bulk the immense amount of 

 heat whose presence is so certainly revealed in these phenomena. 



Of course the rings are the unique and most wonderful feature 

 of the whole system. When Galileo first turned his rude tele- 

 scope upon Saturn, in 1010, he announced that the planet was 

 tri-ple, the projection of the ring on either side making it appear 

 to him as if two smaller planets were joined to the larger one. 

 Gradually, however, these smaller companions decreased in size 

 and finally vanished altogether, much to Galileo's amazement. 

 Later on they reappeared and still further increased his per- 

 plexity. 



Saturn thus remained an enigma to astronomers until an in- 

 crease in the power of telescopes brought out the fact that it was 

 surrounded by a thin, flat ring, which, by its varying positions as 

 seen from the earth, caused the peculiar appearances that so puz- 

 zled Galileo. 



This so-called ring, when seen through large telescopes, ap- 

 pears as a very thin, flat disk with a circular opening in the 

 center in which the planet itself is situated. It lies exactly in 

 the plane of Saturn's equator, and extends considerably more 

 than half the planet's diameter on either side of it. The breadth 

 of the ring is just half the planet's diameter, so that there is quite 

 a space left between its inner edge and the surface of the planet. 



We speak of it as a ring, but in reality there are many of 

 them. When favorably situated, a dark division can easily be 

 detected which separates it into an " outer " and an " inner " 

 bright ring ; while within the last fifty years a third one, inside 

 of the others, was discovered at Cambridge. This innermost of 

 all, known as the " dark " or " crei)e " ring, is a most peculiar 

 object. In appearance it is more like a shadow than anything 

 else, for it seems to be semi-transparent, inasmuch as the out- 

 line of the planet can be seen through it where it crosses the 

 planet's disk. It shades away gradually from the inner edge of 

 the inner bright ring, and becomes fainter until it disappears at 

 some nine thousand miles from the planet's surface. 



What the nature of these rings may be is still in some degree 

 a mystery. They are not gaseous, and it has been shown that 



