In the Pacific Ocean, as well as in the Atlantic, we find a westerly current filling the whole breadth of the tropical zone, from the coast of America to that of Australia and the Indian Archipelago. The best known of its affluxes is the cold Peruvian stream, which, emerging from the Polar Sea, flows with great rapidity along the shores of Chili and Peru, and does not take a westerly direction, before reaching the neighbourhood of the line. It has everywhere a remarkably low temperature, comparatively to the latitude, and this sufficiently accounts for the equal and temperate climate on the coasts of Chili and Peru. Thus, the mean temperature of Callao (12° S. lat.) is only 20° R. while in Rio Janeiro (23° S. lat.), though so much farther from the line, the annual warmth rises to 23·2° R. In the beginning of November, Humboldt found at Callao the temperature of the sea within the current not higher than 15·5°, while outside the stream it rose to 26° or even 28·5° R. Even in the vicinity of the equator, after the current has already assumed a westerly direction, its mean temperature does not exceed 20·5°. But as it advances towards the west, its temperature gradually rises to 27° or 28°. On the western banks of the Pacific the equatorial stream divides into several branches. Part of its waters flow to the south, a greater quantity penetrates through the channels of the south Asiatic Archipelago into the Indian Ocean, the remainder turns to the north-east, on the confines of the Chinese Sea, leaves the eastern coast of the Japanese Islands, and then spreads its warm waters under the influence of north-westerly winds over the northern part of the Pacific. Thus the Japanese stream plays here the same part as the Gulf-stream in the Atlantic, and exerts a similar, though less mighty influence over the climate of the west coast of America, as it is neither so large nor so warm, and, having to traverse a wider ocean, in higher latitudes, naturally loses more of its heat during the passage. [Illustration: Japan Junks.] It is owing to this stream that Sitcha enjoys a mean annual temperature of +7° R., while Nain in Labrador, situated under the same latitude, is indebted to the Greenland current for a summer of +7·8°, a winter of -18·5°, and a miserable annual temperature of -3·6°. On the west coast of North America the analogous trees grow 3° or 4° nearer to the pole, and the aboriginal tribes go naked as far to the north as 52°, a simplicity of toilet that would but ill suit the Esquimaux of Labrador. Besides their beneficial influence on different climates the ocean-currents tend to equalise, or to maintain the equilibrium of the saline composition of sea-water, and thus secure the existence of numberless marine animals. Their movements also contribute to the formation of sand-banks, where at certain seasons legions of fishes deposit their spawn and invite the persecutions of man.