CnAP. II.] INERTION. 27 



earth, they must divide in opposite directions. The 

 one division in each hemisphere will obviously form 

 the streams which in the lower strata run towards 

 the equator at all points from the north-east and 

 south-east ; and the other division in each hemi- 

 sphere, turned towards the poles, being under that 

 influence of change of latitude which tends to carry 

 it eastwards, forms streams in the lower strata flow- 

 ing through the temperate zones, and curving east- 

 wards in their course towards the poles — that is, 

 forming currents running from south-west towards 

 north-east in the northern hemisphere, and from 

 north-west to south-east in the southern hemisphere. 

 Now it is clear that the decreasing circumference 

 of the earth must sooner or later act upon these 

 streams running from the temperate zones towards 

 the poles in the lower strata, in the same manner 

 as upon the streams running from the equator to- 

 wards the poles in the upper strata, and therefore 

 they must gradually, having no other means of pro 

 gressing, turn upwards into the upper strata, through 

 which they must return southwards, until, meeting 

 with the streams flowing from the equator in that 

 upper strata, they form complete circuits of rotation 

 between the temperate zones and the poles — the 

 streams of the lower strata running eastwards in 

 their course towards the poles, and those in the 

 upper strata running westwards in their course from 

 the poles. 



