Chap. II.] INERTION. 21 



Plate IV. figure 1, and then, with the point A as a 

 pivot, bringing it into an upright position as in figure 

 2, In this case the central line of motion, b c, over- 

 whelms the lines of lesser force, r G and ii i in 

 figure 3, on each side ; and sets the fluid in motion 

 in the directions b c G f b and b c i h b. And also, 

 the surface line of motion, b c, overwhelms the line 

 of lesser force, d e, in figure 2, at the bottom of the 

 fluid ; causing a motion in the direction b c e d b. It 

 is then evident that where unequal forces are brought 

 into conflict the lesser force must yield. And we 

 have seen that the force of westward pressure is 

 greater in equatorial than in polar regions ; and also 

 greater at the surface than at the bottom of the 

 ocean. These inequalities in the force of westward 

 pressure result from the inequalities in the velocity 

 of rotation in those parts of the ocean. And we will 

 now consider how these unequal forces are brought 

 into conflict, and what movements result fi:'om their 

 conflicting action. 



This westward pressure would obviously give the 

 water a tendency to change its meridian westwards 

 by the shortest route ; that is, to make as much 

 westing as possible in any given space traversed. 

 And, as the earth's equatorial diameter is greater 

 than its polar diameter, this shortest route westwards 

 is not in lines running due west, but in lines diverg- 

 ing from the equator somewhat northwards and 



