160 THE OCEAN. [Book YI. 



of low water in the central parts of the ocean. But 

 when it is 3 a.m. in the central parts of the Atlantic 

 it is 6 A.M. on the western shores of Europe, which 

 is, approximately, the actual time of high water on 

 those shores two days after full and new moon. 



We have also shown that when the action of the 

 sun and moon passes west of the position in which it 

 has raised a tide, it ceases to be a disturbing influence ; 

 but the water, being placed in that part of the ocean 

 by those or any other forces, is at once carried along 

 with the course of the oceanic circulation caused by 

 the action of vis-inertiae. And by this action the tide 

 is consequently carried from the central parts of the 

 ocean eastwards in the temperate zones, and west- 

 wards in the equatorial regions, by the axial rotation 

 of the earth ; and by the same action, in consequence 

 of the onward motion of the earth southwards through 

 space, the tide is carried northwards through the 

 deep and central parts of the ocean, with a corre- 

 sponding tendency southwards along the shores. 



That the course of the tides thus indicated by 

 theory is that which they actually follow, appears to 

 be shown by the fact of high water occurring at almost 

 the same time on the western shores of Europe and 

 on those of Africa south of the equator ; and also by 

 their having such a general tendency northwards, as 

 well as to synchronise on opposite sides of the ocean, 

 as to have led to the general acceptance of the theory 

 which supposes a great tide-wave to follow the course 

 of the sun and moon westwards through the Grent 



