PORTION OF THE COSMOS. THE SATELLITES. 339 



outermost of all the large planets, Neptune, announced by 

 Le Verrier at Paris, and seen by Galle at Berlin, followed ten 

 months after that of Astrsea. Discoveries now succeed each 

 other with such rapidity, that, after the lapse of a few years, 

 a topography of the solar system appears as antiquated as 

 do statistical descriptions of countries after a similar in- 

 terval. 



Of the 21 satellites at present known, 1 belongs to the 

 Earth, 4 to Jupiter, 8 to Saturn (the last discovered of these, 

 Hyperion, the 7th according to distance, was discovered 

 nearly simultaneously on the two sides of the Atlantic by 

 Bond and Lassell), 6 to Uranus (of which the 2d and the 

 4th are the most securely ascertained), and 2 to Neptune. 



The satellites which revolve round the primary planets 

 constitute subordinate systems, in which the planets appear 

 as the central bodies of domains of various and very diffe- 

 rent dimensions, in which the great solar domain is, as it 

 were, repeated on a smaller scale. According to our pre- 

 sent knowledge, the domain of Jupiter has a diameter of 

 520000 (2080000 Eng.), and that of Saturn 1050000 

 (4200000 Eng.) geographical miles. In the time of Ga- 

 lileo, when the expression of " Mundus Jovialis" was often 

 used to describe the planet Jupiter and its attendant satellites, 

 these analogies between the solar system and the subordi- 

 nate systems included within its limits, contributed much to 

 the more rapid and more general reception of the Copernican 

 views. Such analogies also remind us of the repetition of 

 form and position which are often presented to us in 

 organic life. 



The distribution of the satellites comprised within the 



