286 LEAVES FROM THE BOOK OF NATURE. 



the terrified husbandman. Still, man can conquer even 

 the great magician in the heavens. He knows the hour 

 when the wild army is approaching, he flees from the 

 rage of the threatening tide waves, or he builds gigantic 

 walls, against which they dash hissing and roaring; they 

 tremble for an instant, as if drawing a last, full breath, 

 and then break their iron front into harmless clouds of 

 spray and foam. 



As all attraction is mutual, the earth also causes an 

 enormous tide on the moon ; its power is eighty-one 

 times stronger than that which produces our tides. The 

 moon, we have seen, turns constantly only one side to- 

 wards us ; it is, therefore, but natural to conclude that 

 so immense a power must have produced vast changes 

 in her surface. Some believe, on this account, that, to 

 restore the balance, the sea and the atmosphere of the 

 moon have fled to the opposite side. So much is cer- 

 tain, that, thanks to the loving attraction of our mother 

 earth, the side turned towards us rises at least a thousand 

 feet above the regular form of a globe. 



But the great ocean does not alone show the attrac- 

 tion of the moon in its tides; the huge mass of air, the 

 atmosphere, that surrounds the earth, is likewise exposed 

 to these forces. Ebb and tide on this vast, unmeasured 

 ocean, are, of course, not perceptible far down in its 

 depth, where we poor men breathe painfully ; but only 

 on the surface, to which even the boldest balloon sailor 

 has never yet risen, and perhaps in the very delicate 

 changes of susceptible barometers. The latter are, how- 

 ever, extremely minute; only from time to time some 



