Chap. XXL] THE HEAVENS. 261 



velocity of rotation, is greater along the equator W.E. 

 than along the parallel o y, the ratio which the 

 earth's force, drawing downwards and eastwards, bears 

 to the astral force drawing upwards and westwards, 

 is greater along the parallel o y than along the 

 equator W.E. ; therefore there is a circulation across 

 the meridian a r eastwards, as well as downwards, 

 along • the parallel o y, and westwards, as well as 

 upwards, along the equator E.W. 



And the eastward motion across the meridian is 

 in latitudes intermediate between the equatorial and 

 the polar regions, and not in the highest polar regions, 

 because in the vicinity of N. (Fig. 20 in Proposition X.) 

 the revolvino; forces actins; from v and o neutralise 

 each other (as shown by Proposition X.) leaving the 

 retarding force little resisted by the direct action of 

 the revolving force ; but farther from the pole, as 

 at t, Fig. 20, the normal eastward velocity is increased 

 by the excess of force acting from o and E over that 

 acting from v and W. Therefore, whilst the water 

 lags westwards in the equatorial and in the polar 

 regions under the retarding action of the astral force, 

 it is carried eastwards through the temperate zones 

 by the relative excess of the revolving action of the 

 terrestrial force. 



5. Also, let T, in Fig. 23, be a point on the 45th 

 parallel, and let o, the source of the revolving 

 force, in the equatorial radius c e be so placed that 

 o T be to E as 1*2 is to 1. The revolving force at 



