Hydrography^ and the Art of Navigation. 45 



ed, are very far, in my opinion, from having exhausted the sub* 

 ject. Of this the reader will be able to judge. 



On the cause of Currents, — The most remarkable currents 

 studied by navigators are, in the Atlantic : — 



The current, which, after having gone round the bank of 

 Agullas and the Cape of Good Hope, advances from south to 

 north along the western side of Africa as far as the Gulf of 

 Guinea. 



The current termed equinoctial, which invariably flows from 

 east to west on both sides of the equator, between Africa and 

 America. 



The current which, after having issued from the Gulf of 

 Mexico by the Straits of Bahama, flows at a certain distance 

 along the coasts of the United States towards N.E. as far as the 

 bank of Nantucket, where it changes its direction. 



Lastly, the current, by the action of which the waters of the 

 ocean which bathe the coasts of Spain, Portugal, and Africa 

 from Cape Finisterre as far as the parallel of the Canaries, are 

 all directed towards the Straits of Gibraltar. 



What can be the cause of these currents ? 



The trade-winds, according to some, by continually blowing 

 in the Indian Ocean from east to west, must produce a liquid 

 intumescence on the eastern coast of Africa near the equator. This 

 accumulated water flows continually from north to south through 

 the Straits of Mosambique. When it reaches the parallel of 

 the Cape of Good Hope, the eastern wall or mound which had 

 hitherto maintained it disappearing, the water necessarily flows 

 westward. It is thus that the current of the Agullas is 

 formed. 



The equinoctial current of the Atlantic is attributed to the 

 constant impulsion of the trade-wind on the waters in the vici* 

 nity of the equator to the north and south. 



The Atlantic equinoctial current, in this respect resembling 

 the equinoctial current of the Indian sea, must produce a great 

 accumulation of water along the first coast which presents itself 

 as a barrier to it ; that coast is America. From this results a 

 general movement of the Caribbean sea towards the strait which 

 separates the eastern point of Yucatan from the western point of 

 Cuba, as well as an elevation of the level of the sea in the Gulf 



