CLIMATES OF THE OCEAN. 301 



the Atlantic to the other. This line or band may have its cycles 

 also, but they are probably of long and uncertain periods. 



866. The fact has been pretty clearly established by the dis- 

 coveries to which the wind and current charts have led, that the 

 western half of the Atlantic Ocean is heated up, not by the Gulf 

 Stream alone, as is generally supposed, but by the great equato- 

 rial caldron to the west of longitude 35°, and to the north of Cape 

 St. Koque, in Brazil. The lowest reach of the 80° isotherm for 

 September — if we except the remarkable equatorial flexure (Plate 

 IV.) which actually extends from 40° north to the line — to the 

 west of the meridian of Cape St. Roque, is above its highest reach 

 to the east of that meridian. And now that we have the fact, how 

 obvious, beautiful, and striking is the cause ! 



867. Cape St. Koque is in 5° 30^ south. Now study the con- 

 figuration of the Southern American Continent from this cape to 

 the Windward Islands of the West Indies, and take into account 

 also certain physical conditions of these regions : the Amazon, al- 

 ways at a high temperature because it runs from west to east, is 

 pouring an immense volume of warm water into this part of the 

 ocean. As this water and the heat of the sun raise the temperature 

 of the ocean along the equatorial sea-front of this coast, there is no 

 escape for the liquid element, as it grows warmer and lighter, ex- 

 cept to the north. The land on the south prevents the tepid wa- 

 ters from spreading out in that direction as they do to the east of 

 35° west, for here there is a space, about 18 degrees of longitude 

 broad, in which the sea is clear both to the north and south. 



868. They must consequently flow north. A mere inspection 

 of the plate is suihcient to make obvious the fact that the warm 

 waters which are found east of the usual limits assigned the Gulf 

 Stream, and between the parallels of 30° and 40° north, do not 

 come from the Gulf Stream, but from this great equatorial cal- 

 dron, which Cape St. Eoque blocks up on the south, and which 

 forces its overheated waters up to the fortieth degree of north lat- . 

 itude, not through the Caribbean Sea and Gulf Stream, but over 

 the broad surface of the left bosom of the Atlantic Ocean. 



869. Here we are again tempted to pause and admire the beau- 

 tiful revelations which, in the benign system of terrestrial adapta- 



