THEORY OE THE TIDES. 95 



the other side of the planet, according to the general theory, the 

 waters ought to swell in a corresponding wave, and that from a pre- 

 cisely contrary cause. The liquid strata on this part of the earth 

 being further from the moon than the solid kernel, are less attracted 

 than it, and in consequence must remain slightly behind, thus form- 

 ing a new intumescence, the summit of which will be found on a pro- 

 longation of the line uniting the planet with its satellite. Considered 



* Fig. 26.— Lunar tide. 



as a whole, the mass of marine waters would thus assume the form of 

 an ellipsoid, having its greater axis directed towards the moon, which 

 is the centre of attraction. It results from this, that the tide ought 

 to be nothing at all, or very slight, at the poles ; since in its revolu- 

 tion, the moon while moving to the north and south of the equator 

 maintains itself at the zenith of tropical or sub-tropical regions. 



If the earth remained immovable these two waves would advance 

 slowly, following the course of the moon ; but in consequence of the 

 rotation of the earth, they ought to move rapidly in pursuit of one 

 another over its circumference: the wave of the greatest attraction 

 moving incessantly over the part lighted by the rays of the moon, 

 while the wave of the weakest attraction is propagated from the 

 other side of the earth on the part furthest from the satellite. In 



* This illustration, as well as figs. 27 and 29, have been borrowed from the fine work by 

 M. Amedee Guillemin, entitled Le del. 



