98 



THE OCEAN. 



in consequence it would raise the tides into real mountains as high 

 as the Cevennes,* if the true cause of the tides was not to he found 

 in the difference of attraction exercised on the waters of the dif- 

 ferent parts of the earth. The distance from the moon being equal 

 to 60 terrestrial radii only, the action of the satellite is much 

 stronger over the nearer oceanic regions than over the waters situated 

 thousands of miles further off. The sun, on the contrary, acts nearly 

 in the same manner on the watery particles of the whole surface of 

 all the seas. According to the results obtained by the calculations of 

 mathematicians, the attractive force exercised by the sun in elevating 

 the waves is, as compared to that of the moon, in the proportion of 

 about a third. 



Two tidal waves, the lunar wave and the solar wave, are thus 

 raised on the surface of the sea. They ought to revolve, the one ii 



Fig. 29.— Tide during Quadrature. 



the space of 24 hours 50 minutes, and the other in 24 hours. Bu< 



these two waves so distinct in their origin are not separated in theii 



♦ 5000 to 6000 feet high. 



