Increasing quickly in bulk, and spreading out more and more on both sides of the equator, it flows rapidly due west toward the coast of South America. At the eastern point of South America, Cape St. Roque, the equatorial current splits into two, and one portion trends southward to deflect the isotherms of 21°, 15°.5, 10°, and 4°.5 C. into loops upon our maps, thus carrying a scrap of comfort to the Falkland Islands and Cape Horn; while the northern portion follows the northeast coast of South America, gaining continually in temperature under the influence of the tropical sun. Its speed has now increased to sixty-eight miles in twenty-four hours, and by the union with it of the waters of the river Amazon, it rises to one hundred miles (6.5 feet in a second), but it soon falls off again when it gets into the Caribbean Sea. Flowing slowly through the whole length of this sea, it reaches the Gulf of Mexico through the Strait of Yucatan, when a part of it sweeps immediately round Cuba; but the main stream, “having made the circuit of the Gulf of Mexico, passes through the Strait of Florida; thence it issues as the ‘Gulf Stream’ in a majestic current upward of thirty miles broad, two thousand two hundred feet deep, with an average velocity of four miles an hour, and a temperature of 86° Fahr. (30° C.).” The hot water pours from the strait with a decided though slight northeasterly impulse on account of its great initial velocity. Mr. Croll calculates the Gulf Stream as equal to a stream of water fifty miles broad and a thousand feet deep flowing at a rate of four miles an hour; consequently conveying 5,575,680,000,000 cubic feet of water per hour, or 133,816,320,000,000 cubic feet per day. This mass of water has a mean temperature of 18° C. as it passes out of the gulf, and on its northern journey it is cooled down to 4°.5, thus losing heat to the amount of 13°.5 C. The total quantity of heat therefore transferred from the equatorial regions per day amounts to something like 154,959,300,000,000,000,000 foot-pounds. This is nearly equal to the whole of the heat received from the sun by the Arctic regions, and, reduced by a half to avoid all possibility of exaggeration, it is still equal to one-fifth of the whole amount received from the sun by the entire area of the North Atlantic. The Gulf Stream, as it issues from the Strait of Florida and expands into the ocean on its northward course, is probably the most glorious natural phenomenon on the face of the earth. The water is of a clear crystalline transparency and an intense blue, and long after it has passed into the open sea it keeps itself apart, easily distinguished by its warmth, its color, and its clearness; and with its edges so sharply defined that a ship may have her stem in the clear blue stream while her stern is still in the common water of the ocean.