Chap. II.] INERTION. 31 



temperate zones towards the poles. These streams 

 on the eastern side of the ocean, flowing from the 

 temperate zones towards the poles, are under that 

 influence of change of latitude which tends to carry 

 them eastwards, and they must therefore tend to 

 follow the course of the coast, until, after sweeping 

 through the polar regions, they appear on the western 

 side of the ocean as streams flowing from the poles 

 towards the equator. And as on the western coast, 

 flowing towards the equator, they come under that 

 influence of change of latitude which tends to carry 

 them westwards, they must therefore tend to follow 

 the course of the western coast, until they meet the 

 streams flowing from the equator on that coast. 

 Thus the streams turned polewards from the tem- 

 perate zones, on the east side of the ocean, rejoin 

 their parent streams on the west side of the ocean, 

 forming continuous streams encircling each of the 

 polar districts of the ocean. And thus, therefore, 

 the ocean is divided, as far as its currents are con- 

 cerned, into four separate districts, each encircled by 

 a revolving current — an equatorial and a polar dis- 

 trict being formed on each side of the equator, as 

 shown in Plate YI. 



Section II. — Equatorial Counter-Currents. 



We have, however, as yet, in this ocean, applied 

 only that action of westward pressure which results 

 from the difference in the relative forces of that 



