240 PREFACE TO THE 



direction, and compelled to regurgitate in the opposite 

 one by the obstacles which it meets with, as the great 

 Atlantic. This at least appears to be the import of 

 the expressions of which he makes use. That the 

 period of the revolution of the waters round the earth 

 is greater than twenty-four hours, appeared to Bacon 

 to be in entire accordance with the retardation of the 

 diurnal motion of the planets. All the inferior orbs 

 lag behind the starry heaven, and that of the moon 

 most of all ; wherefore the moon s diurnal period is 

 more nearly the same as that of the waters than any 

 other. 



In these views there is an absolute confusion be 

 tween the bodily motion of water as in a current, 

 and the propagation of an undulation ; a confusion 

 not unnatural, seeing that to conceive the motion of 

 an undulation apart from that of the matter of which 

 it is composed is by no means easy. Scaliger how 

 ever might have learned from Cardan, notwithstand 

 ing the arrogance with which he treats him, to dis 

 tinguish between them. For Cardan, after saying 

 that high water follows the moon, inquires why the 

 motion of the flood current is so much slower than 

 the moon s. He answers : &quot; Causa est, quod non tota 

 aqua, nee una pars lunam sequitur, sed proximae in 

 proximas transfer untur, velut si quis carnem com- 

 primens tumorem elevet, caro quidem parum loco 

 movebitur, celerrime tamen tumor per totum crus 

 transferetur.&quot; l 



It became necessary, when the flood current was 

 confounded with the motion of the tide wave, to as 

 sign a cause for the reciprocating motion of ebb and 



i De Subtilit. ii. p. 408. 



