426 THE SUPPOSED SELF-LUMINOSITY 



of all pre-judgment, and to esteem the treasure-house of physical 

 variety still unexhausted, aud the phases of physical appearance ^t ill 

 not all seen. And should this most unexpected and important 

 fact be hereafter established, we shall then be presented with a start- 

 ling and striking converse to the fact arrived at by the masterly in- 

 duction of the lamented Bessel, with regard to the stars Sirius 

 and Procyon — the first, one of the most majestic orbs which our 

 firmament can claim, — that each is associated in binary combination 

 with masses yet mightier than themselves, like our planets opaque 

 and non-luminous ; suns of darkness, whose light, if ever they shone, 

 has waned and gone out for ever. And, on the suppo the 



planet in question being self-luminous, it becomes an interesting ob- 

 ject of inquiry whether, from any adjacent system, our sun can ap- 

 pear with it to constitute a double star." 



Such is the reviewer's statement. Now, opinions have lately been 

 set forth with great skill and plausibility tending to the belief that 

 this earth is the only planet fit for the habitation of intelligent beii 

 and that the other planets of the Solar System being either too 

 the sun, or too remote from it, receive either too great or too little 

 an amount of light and heat to fit them for the abodes of creatures 

 constituted like ourselves. 



If, however, future observation should confirm this statement that 

 Neptune is itself luminous, it must somewhat modify tlv 

 for it will prove that a planet even at the great distance which Nep- 

 tune is from the sun may after all not be such a dark world, and not 

 quite so miserable as it has been represented. And this selr'-lumin- 

 osity of Neptune m tv also account for its less complicated arrange- 

 ments for compensation by means of moons for the small amount of 

 light it receives from the sun. For it has only one satellite — at least 

 Mr. Lassel, who has lately moved his celebrated Reflecting Telescope 

 to Malta where the atmosphere is peculiarly well adapted for astro- 

 nomical observations, states that he is satisfied there is only one satel- 

 lite belonging to Neptune — or at least if there be others, there is 

 no prospect of discovering them with our present telescopes. The 

 suspicion entertained by Mr. Lassel and Mr. Bond that there is a 

 ring round Neptune has since been abandoned. I may here mention 

 that Mr. Lassel also states as the result of his late observations that 

 he is satisfied there are only four satellites belonging to Uranus. 



, these facts give rise to some reflections — and it may not be 

 out of place here to offer a few observations upon the varieties which 

 exist amongst the planetary bodl l ds their physical conditions, 



and to take a cursory view of the Solar System generally ; from which 



