NEWS FROM THE MOON. 22$ 



in the habitability of our satellite). The theory was 

 originally suggested by a mathematical inquiry of 

 singular profundity. The skilful German mathe- 

 matician, Hansen, found reason to believe that if 

 the moon's centre of gravity is not exactly at the 

 middle point of that diameter of hers which is directed 

 earthwards, her movements must give evidence of the 

 fact. If the centre of gravity were farther away 

 than the middle point she would show a slight pecu- 

 liarity of motion in one direction, while if the centre 

 of gravity were nearer than the middle point she 

 would show a peculiarity of the opposite kind. On 

 examining the moon's actually recorded motions, Han- 

 Ben considered that he had evidence sufficing to prove 

 that the centre of gravity is more than thirty 

 miles farther away than the middle point just men- 

 tioned. Now clearly, if the moon's shape is very nearly 

 globular, but she is like a loaded die, heavier on one side 

 than the other, her oceans and atmosphere must pass 

 over to the loaded side. To use the emphatic mode of 

 describing matters employed by Sir John Herschel in 

 a letter to the present writer, the farther side of the 

 moon, according to Hansen's view, is 'like a great lake 

 basin, nearly forty miles deep.' Of course, Herschel did 

 not mean that there is a great concavity on that side, 

 any more than a geographer would mean that the ocean 

 bottom is concave, if he spoke of the ocean basin. But 

 the state of the farther side of the moon, according to the 

 theory we are considering, is precisely as though matter 

 were excavated away to a depth of nearly forty miles, 



