CONDITION OF THE LARGER PLANETS. l8l 



planes in which they travel. It would be absurd to 

 suppose that globes so magnificent were made for no 

 special purpose, but we can conceive no special purpose 

 they can subserve except to be the abodes of life ; 

 therefore they are worlds like our earth (though the 

 sun, constructed on a still more magnificent scale, is 

 certainly not such a world, or the abode of life). Their 

 moons are manifestly intended to make up to them 

 for their remoteness from the sun (only, when we 

 -calculate how much light these moons reflect to their 

 primaries we find that they supply but a small fraction 

 of the amount we receive from our moon). The rings 

 of Saturn were manifestly intended for the benefit of 

 Saturn's inhabitants (though they only reflect light to 

 the summer hemisphere of the planet, and besides 

 turning their darkened side to the other hemisphere, 

 cut off the whole of the sun's light for many months, 

 in some cases for several of our years, in succession). 

 The belts on Jupiter and Saturn may be likened again 

 to our trade wind zones, to which, however, they bear 

 not the remotest resemblance, whether we consider 

 their condition at any given time, or the rapid changes 

 they undergo from time to time. In fine, the argu- 

 ments used by the few writers who have condescended 

 to present even a show of reasoning in favour of the 

 theory that Jupiter and Saturn resemble our earth in 

 condition, amount practically to this that, assuming 

 all planets to be generally similar, Jupiter and Saturn 

 are like our earth in general respects, in which case 

 they also resemble her in several details. 



