344 



MEXICO, CENTRAL AMERICA, WEST INDIES. 



per day. But the whole basin is not filled by this vast body, which in some places 

 gives rise to lateral counter-currents and backwaters, as between Colon and Carta- 

 gena, where the reflux has a velocity of 1 mile an hour. 



After passing at an accelerated speed through the Banks Strait, between 

 Jamaica and the Mosquitos reefs, the main stream is joined by an affluent setting 

 from the Atlantic through the Windward Channel. Hence an enormous liquid 

 mass passes at a velocity of from 2 to 3 miles through the Strait of Yucatan 

 into the Gulf of Mexico, where it takes the name of the " Gulf Stream." 



At first it ramifies into two branches, one of which, following the north coast 

 of Cuba, sets towards Florida Strait, while the other broadens out in the spacious 

 basin of the Gulf and develops an intricate system of counter- currents. Towards 



rig. 161.— Main Cueeents of the American Mediteeeanean. 

 Scale 1 : 45,000,000. 



30' 



Chief submarine banks. 



620 Miles. 



the centre of this nearly circular sea the waters seem to be in a state of equili- 

 brium, while at the periphery they move parallel with, but at some distance from, 

 the surrounding coasts. South of the Mississippi delta the turbid fluid of the 

 great river is impelled in a straight line eastwards by the blue waters of the Gulf 

 Stream. Thus a junction is effected of the two branches about the southern 

 entrance of Florida Strait, through which the whole mass disembogues like a 

 mighty river in the broad Atlantic. At the narrowest part, between Jupiter 

 Inlet on the Florida side and Memory Rock in the Bahamas, the stream is con- 

 tracted to a width of 56 miles, with an extreme depth of 450 fathoms. In this 

 contracted channel the velocity varies from 2 to 6 miles, the average being 

 about 3, and the discharge, according to Bartlett, 175 billions of cubic feet 

 per second, or 15,260 trillions per day. 



