52 THE POPULAR SCIENCE MONTHLY. 



dence we have as to the brightness of Saturn and Jupiter. If these 

 planets were perfectly cloud-encompassed, we should expect them to 

 shine much more brightly than earthy or rocky globes of equal size, 

 similarly placed, and surrounded only with a tenuous atmosphere. In 

 fact, we should expect the planets, if cloud-encompassed, to shine about 

 four times as brightly as though they were constituted like our moon. 

 They would in that case, however, be white planets, not only as seen 

 by the naked eye, but when examined with the telescope. In point 

 of fact, they shine, according to the very careful measurements of 

 Zollner, about as brightly as though they were perfectly cloud-envel- 

 oped ; but they are neither of them found to be white under telescopic 

 scrutiny. Bond, of America, says, indeed, that Jupiter shines four- 

 teen times as brightly as he would if constituted like the moon ; and 

 though this is a surprising result, and would imply that some portion 

 of Jupiter's light is certainly inherent, it is well to notice that it is 

 confirmed by De La Rue's photographic researches ; for he found that 

 a photographic image of the moon can be taken in about two-thirds of 

 the time required in Jupiter's case, whereas the moon should require 

 but a twenty-fifth of the time required by Jupiter, if her reflecting 

 power were equal to his, since Jupiter is five times as far away from 

 the sun. It would follow from this that Jupiter shines nearly seven- 

 teen times as brightly as he would if he were constituted like the 

 moon. Taking the lowest estimate, however, we find that both Saturn 

 and Jupiter shine much more brightly than planets of equal size and 

 similarly placed, but having a surface formed of any kind of earth or 

 rock known to us. And, taking into account the well-marked colors 

 of these planets, it follows as an almost demonstrated fact that each 

 shines with no inconsiderable portion of inherent light. 1 



So soon as we view Saturn as a globe intensely heated, and the 

 scene of forces of enormous energy, we are compelled to dismiss the 

 idea that he is the abode of life. But, singularly enough, this conclu- 

 sion, which was rejected by Brewster as rendering apparently unin- 

 telligible the existence of so large and massive an orb, girt about by a 

 system so complex and beautiful, does in reality at once present, in an 

 explicable aspect, not merely the vast bulk of Saturn himself, but the 

 scheme over which he bears sway ; for, as it seems to us, not the least 

 of the objections against the theory that Saturn is an inhabited 

 world, is found in the useless wealth of material exhibited, on that 



1 I might take, as equally convincing proof of the intensely heated condition of these 

 giant planets, the fact that the shadows of the nearer satellites, which theoretically should 

 be black, have sometimes been seen to be gray, and never appear to be much darker than 

 the fourth satellite in transit. And, as sufficient proof of the great depth of Jupiter's at- 

 mosphere, I could take the fact that sometimes two shadows have been seen, both belong- 

 ing to the same satellite. However, it would require more space than can here be spared 

 to show the force of these facts. I remind the reader that whatever is proved respecting 

 the condition of Jupiter, may be regarded as rendered probable of his brother giant, 

 Saturn. 



