Chap. II.] INERTION. 37 



Let z be the point at which the stream h meets 

 the stream s w n e. 



Then from the meeting at z the offset i falls into 

 the course of rotation s w n e ; and the offset R falls 

 into the course of the stream o e, forming an un- 

 broken course of cu'culation, which may be termed 

 the natural course of the surface currents within each 

 district. 



Since the streams a b c and o r both tend east- 

 wards in their course from the equator, and the stream 

 E H tends westwards in its course to the equator, the 

 latter must, sooner or later, after leaving the point x, 

 be thrown against the stream a b c, and then be 

 forced eastwards, running counter to that stream as 

 far as the point at which the stream o R diverges 

 from it. 



Section V. — Vertical Circulation within the Districts. 



Now the axis of this district being inclined as 

 before described, it is clear that about the central 

 parts of the district an under current must be run- 

 ning southwards, whilst the surface above it is flow- 

 ing northwards. Let us consider how this is effected. 

 The point x (Plate IX., figure 2), as already de- 

 scribed, is that at which the opposmg streams abc 

 and o R meet with equal force as surface currents. 



But, since the stream a b c is that which is de- 

 flected by the coast-line, which deflects the whole 

 mass of water from the surface to the bottom of the 



