ASTRONOMY AND METEOROLOGY. 377 



continually changing, and that their maximum number, in the normal 

 condition of the mass, does not exceed twenty. According to Mr. Bond, the 

 power which sustains the centre of gravity of the ring is not in the planet 

 itself, but in its satellites ; and the satellites, though constantly disturbing 

 the ring, actually sustain it in the very act of perturbation. Mr. Otto 

 Struve and Mr. Bond have lately studied, with the great Munich telescope, 

 at the observatory of Pulkowa, the third ring of Saturn, which Mr. Lassels 

 and Mr. Bond discovered to be fluid. They saw distinctly the dark interval 

 between this fluid ring and the two old ones, and even measured its dimen- 

 sions ; and they perceived at its inner margin an edge feebly illuminated, 

 which they thought might be the commencement of a fourth ring. These 

 astronomers are of opinion that the fluid ring is not of very recent forma- 

 tion, and that it is not subject to rapid change ; and they have come to the 

 extraordinary conclusion, that the inner border of the ring has, since the 

 time of Huygens, been gradually approaching to the body of Saturn, and 

 that we may expect sooner or later, perhaps in some dozen of years, to see 

 the rings united icitli the body of the planet" 



With this deluge impending, Saturn would scarcely be a very eligible 

 residence for men, whatever it might be for dolphins. But Sir David 

 saves himself by the clause of his proposition, in which he maintains that, 

 if the planets and stars are not already habitable worlds, they are in a state 

 of preparation for the residence of intelligent beings. 



ON THE EXISTENCE OF A LTJNATl ATMOSPHERE. 



The universally accredited theory, that the moon is uninhabited be- 

 cause she has no atmosphere, has received, from a recent discovery, a blow 

 that will unsettle it at least. That the moon, as far as we have yet been 

 able to examine her, has no atmosphere, or at least none of sufficient 

 density to conform to our optical laws and the demands of any animal 

 life known to us, is unquestionable. But this can be positively affirmed 

 of only one side of our satellite ; for, as will be remembered, although 

 she revolves upon her axis, she constantly presents but one side to the 

 earth. Now, it has been discovered by calculation, and demonstrated as 

 geometrical fact, that the moon's centre of form is eight miles nearer to us 

 than her centre of gravity, through which, of course, her axis of revolu- 

 tion must pass ; or, in other words, this side of the moon is sixteen miles 

 higher than the other. If, therefore, we suppose that the moon has an 

 atmosphere such as ours, it would be of such extreme rarity on the only 

 side exposed to our observation, that, for optical effect and animal life, it 

 might as well not exist ; for mountains upon the earth, none of which 

 are over five miles above the level of the sea, have been ascended to a 

 height at which life could not be supported for any length of time, and 

 still mountains have stretched above the panting traveller. What, th n , 

 must be the atmosphere at four limes such an elevation ? The conclusion 

 seems inevitable, that, although the hither side of the moon is uninhabita- 



