alone, as is generally supposed, but (§ 131) by the great equatorial caldron to the west of longitude 35°, and to the north of Cape St. Roque, 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, how beautiful, and striking is the cause! Cape St. Roque is in 5° 30' south. Now study the configuration 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, always 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, except to the north. The land on the south prevents the tepid waters 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: they must consequently flow north. A mere inspection of the plate is sufficient 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 caldron, which Cape St. Roque blocks up on the south, and which dispenses its overheated waters up towards the fortieth degree of north latitude, not through the Caribbean Sea and Gulf Stream, but over the broad surface of the left bosom of the Atlantic Ocean.
727. The warmest sides of oceans and the coldest shores of continents in juxta-position.—Like the western half of the North Atlantic Ocean, the western half of every one of the three great oceans is the warmer. The great flow of warm water in the North Pacific is with the "Black Stream of Japan," on the Asiatic side; in the South Pacific it is with the Polynesian drift, on the Australian side: opposite to these warm Pacific currents and on its eastern side, are the Humboldt current in one hemisphere, and the California current in the other—cold currents both. In the South Indian Ocean, the warm water is with the Mozambique
