1865.] Saturn and its System. 725 



a belief from general analogy that the planet is inhabited, and after 

 labouring apparently to prove a similarity between its conditions and 

 those on the Earth, the author concludes that it is probably " not a 

 suitable habitation for beings constituted like the inhabitants of our 

 globe." But if it can be clearly shown that the physical conditions 

 are irreconcilable with the existence of living beings like those which 

 now tenant, or are known to have tenanted, the Earth, all other in- 

 quiries must be beside the question ; and we cannot understand how, 

 on the principles employed, inhabitants can be granted to Saturn, and 

 yet denied to the Moon, or even to the Sun. In his notes on the 

 habitability of the Moon, Mr. Proctor confines himself to the discussion 

 of certain interesting but doubtful questions, and does not offer any 

 opinion as to our Satellite's being the abode of living beings ; yet, 

 from the general tenour of his language, we infer that he considers it 

 uninhabited. But why, if Saturn can be supposed to be the abode of 

 beings different from any on the Earth, may not the Moon be supposed 

 the abode of others different from those on either ? The only life we 

 know anything about is life in its terrestrial manifestations. This 

 life requires certain conditions, and if they are absent it must be 

 absent also. Further than that we are not warranted in going. We 

 cannot say that, although the only kind of life we do know anything 

 about is impossible because of the non-existence of some of its essen- 

 tial conditions, yet some other form of life probably is present. But 

 are the conditions on Saturn such as necessarily to shut out life in this 

 restricted sense ? We cannot agree with the author that the dimness 

 of the planet's light and the length of its year are so, when there is 

 abundant proof of life on the Earth in situations from which light is 

 absent altogether, and where the conditions, instead of only varying in 

 long intervals, never vary at all. Many things have yet to be deter- 

 mined with respect to the light which reaches the outer planets, before 

 it will be prudent to speak positively as to its dimness. The great re- 

 flective capacity of the globe and rings in the case of Saturn, and the 

 photographic intensity of this reflected light, have already been clearly 

 established. The matter is still under inquiry, and in the number of 

 the ' Comptes Kendus' for June 5th is a very interesting communica- 

 tion from Father Secchi, in which the identity in many respects of the 

 atmospheric conditions of Jupiter and Saturn is pointed out. As Mr. 

 Proctor himself states, the light to the Earth was possibly much less 

 in earlier times, when huge creatures of the bat kind were relatively 

 very abundant. All his reasoning from palseontological data, however, 

 is not so reliable even as this. It seems strange, for instance, to hear 

 the cumbrous forms of extinct animals adduced as a reason for sup- 

 posing that the dimensions of our planet were once much larger than 

 at present, and therefore gravity at its surface less, when some of the 

 hugest and most weighty of them lived only so recently as the later 

 Tertiary period, during which there is no reason for thinking the size 

 differed from what it is now. 



The discovery of the disturbance of the periods of Jupiter and 

 Saturn, known as the long inequality, when first made by Halley, was 

 thought to throw doubt on the law of gravitation. The effect of mutual 



