582 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



the 25th degree of north latitude. _ Thus the elliptical circuit of 

 the north Atlantic is completed. 



The attentive and critical observer will now perceive that a cur- 

 rent cannot flow alternately north and south, in any ocean, without 

 moving in an elliptical orbit, the diameter of which east and west, 

 will be in proportion to its diameter north and south. 



The two points in an ellipse, where the easterly velocity of the 

 current is the same as that of the earth, may be called neutral 

 points. A local current is always neutral at its starting point. 

 When neutral water proceeds from any point to a higher or lower 

 latitude, it accumulates a greater and greater difierence of easterty 

 velocity the further north or south it flows, provided it does not 

 cross the equator. 



We have here a perfect explanation of the fact so well known 

 to navigators, that the currents near the equator run almost directly 

 west, while those near the polar regions run east. We can also 

 understand why a portion of an elliptical current, when it flows 

 northerly from the equator, must flow north-ivesi, and why such a 

 current which flows southerly from the northern regions, must 

 flow south-easL 



Six Turning Points in Ellipses. 

 If we analyze an elliptical current we shall find that it has six 

 turning points which deserve to be separately considered. In the 

 northern hemisphere they may be enumerated as follows: 



1. The ivest neutral 'point^ — which in the north Atlantic is in or 

 near the Gulf of Mexico, and in the north Pacific, in or near the 

 China Sea. Here the waters of the current possess the same velo- 

 city as the earth. From this point the water runs north-east just 

 as a local current would. 



2. The due east jpoint, — where the current has expended all its 

 northern tendency, and where its easterly surplus force is at its 

 maximum. In the north Atlantic this point is probably very near 

 Newfoundland, and in the north Pacific near Kamschatka. 



3. The south-east turning 'point. — This is where the current 

 ceases to move due east, and, growing colder, turns south-easterl3\ 

 This point is, in the north Atlantic, near the Bay of Biscay, and in 

 the north Pacific, near British Columbia. 



4. The east neutral point. — This is on the eastern side of the 

 ellipse, where the current has the same easterly velocity as the 

 earth has, and from which it moves south-west to the equator, just 

 as a local cold current would. In the north Atlantic this point is 



