272 THE NI-IBULAli HYPOTHESIS. 



eight secondary planets revolving round liiin, the like- 

 ness is still more close in arrangement as in number : 

 the three outer satellites are large, the inner ones small ; 

 and the contrasts of si/.e are here much greater between 

 the largest, which is nearly as big as Mars, and the 

 smallest, which is with difficulty discovered even by the 

 best telescopes. 



Moreover, the analogy docs not end here. Just as with 

 the planets, there is at first a general increase of size on 

 travelling inwards from Neptune and Uranus, which do 

 not ditler very widely, to Saturn, which is much larger, 

 and to Jupiter, which is the largest ; so of the eight satel 

 lites of .Saturn, the largest is not the outermost, but the 

 outermost save two; so of Jupiter s four secondaries, the 

 largest is the most remote but one. Now these analogies 

 are inexplicable by the theory of final causes. For pur 

 poses of lighting, if this be the presumed object of these 

 attendant bodies, it would have been far better had the 

 larger been the nearer: at present, their remoteness ren 

 ders them of less service than the smallest. To the Nebu 

 lar Hypothesis, however, these analogies give further sup 

 port. They show the action of a common physical cause. 

 They imply a line of genesis, holding in the secondary sys 

 tems as in the primary system. 



Still more instructive t-hall we find the distribution of 

 the satellite s their absence; in some instances, and their 

 presence in other instances, in smaller or greater numbers. 

 The argument from design fails to account for this distri 

 bution. Supposing it be granted that planets nearer the 

 Sun than ourselves, have no need of moons (though, con 

 sidering that their nights are as dark, and, relatively to 

 their brilliant days, even darker than ours, the need seems 

 quite as great) supposing this to be granted ; what is to 

 be said of Mars, which, placed half as far again from the 

 Sun as we are, has yet no moon ? Or again, how are we 



