PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 583 



near the west coast of northern Africa. In the north Pacific it is 

 near the coast of California. 



5. The due west or equatorial 'point ^ — is where the current 

 ceases to flow southward, but moves due west. Having acquired 

 a maximum of easterly difference, or westing, and expended the 

 force that sent it southward, it can only move directly westward. 

 In the north Atlantic this point is near the western extremity of 

 Africa, and about five degrees north of the equator. In the north 

 Pacific it is about ten degrees north of the equator, and several 

 hundred miles west of Central America. 



. 6. The north-ioest turning point, — is where the current, being 

 heated, overflows and leaves the equator, and begins to move 

 north-west. In the north Atlantic this is near the point of Cape 

 St. Roque, in South America; and in the north Pacific, it is in or 

 near the East Indian Archipelago. 



The Six Turning Points in the Elipses of the Southern 



Hemisphere. 



In the southern hemisphere, the six turning points, thouo-h of 

 course, the directions are reversed, are repeated in each of the 

 three great oceans. We are not practically as well acquainted 

 with the currents in the extreme south, as we are with the north- 

 ern currents; and we cannot, therefore, point out, in all cases 

 with as much precision as we could wish, the localities where 

 they turn. I have no other means of obtaining positive informa- 

 tion concerning the actual currents than those possessed by all 

 my readers; but, it appears to me, that when the laws that o-qv- 

 ern them are well understood, the existence and direction of a 

 cnrrent may be indicated theoretically, in any locality, the general 

 geography of which is known, even if no actual observations have 

 been made. Just as an accomplished astronomer^ when he is cor- 

 rectly informed from actual observations concerning a few points 

 in the path of a comet, can predict its course in regions of space 

 far beyond the scope of human vision — so the geonomer, when the 

 principles and laws of oceanic circulation are well understood, can 

 predict, with equal accuracy, in what direction the elliptical or 

 the local currents must necessarily flow in any unexplored sea. 



1. The loest neutral point, in the southern hemisphere, from 

 which the elliptical current flows southeast like a local current 

 appears, in the South Atlantic, to be near the mouth of the La 

 Plata. If we rely upon theoretical principles, we must presume 



