Through this strait, after a strong trade wind has been blowing for a time, the current sets into the Gulf of Mexico at the rate of two or three knots an hour. Here the waters of the tropical seas are mingled with the waters of the Mississippi, the Balize, the Rio Grande, the Colorado, the Alabama, and other large streams which empty into the Gulf of Mexico; and turning off to the eastward, this body of water is driven along between the coasts of Cuba and Florida until it strikes the Salt Key Bank and the Bahamas, when it receives another considerable addition from the currents, which, from the same causes, are continually setting west through the Old Bahama and New Providence Channels. It is then forced northward along the coast of Florida and the Middle States. The stream becomes wider as it extends north, diminishes its velocity, and gradually changes its temperature, until it strikes the shoals south of Nantucket and the Bank of St. George, when it branches off to the eastward, washes the southern edge of the Bank of Newfoundland, and a portion of it is lost in the ocean between the Western and Canary Islands; and another portion, sweeping to the southward past the Cape de Verdes, is again impelled to the westward across the Atlantic, and performs its regular round. The current always moving in the same circuitous track, forms, according to Mr. Maury, to whose scientific labors the commercial world is deeply indebted, an IMMENSE WHIRLPOOL, whose circuit embraces the whole North Atlantic Ocean. In the centre of the whirl is a quiet spot, equal in extent of area to the whole Mississippi valley, unaffected by currents of any kind. And here, as a matter of course, the greater part of the gulf-weed and other floating materials, which are carried round by the current, is eventually deposited. This is the "Sargasso Sea" of the ancients. Columbus crossed this "weedy sea" on his quest after a western passage to India. And the singular appearance of the ocean, thickly matted over with gulf-weed, caused great alarm among his companions, who thought they had reached the limits of navigation. A current of a character similar to the Gulf Stream only not so strong is experienced along the east coast of Africa, from Mozambique to the Lagullas Bank, off the Cape of Good Hope. This current is undoubtedly caused by the trade wind forcing the water towards the coast of Africa. But in this case it is not driven into a narrow passage, like the Gulf of Florida, which would greatly increase its velocity. The temperature of the water in the current off the Cape of Good Hope is also several degrees higher than the ocean waters in the neighborhood of the current.