272 THE NEBULAU HYPOTHESIS. 



eight secondary planets rev^olving round him, 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 size 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 does not end here. Just as with 

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

 travelling inwards from iSTeptune and Uranus, which do 

 not diifer 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. ]N"ow 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 law of genesis, holding in the secondary sys- 

 tems as in the primary system. 



Still more instructive shall we find the distribution of 

 the satellites — 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 seema 

 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 



