The main island of Japan, being situated in the temperate zone, enjoys, for the most part, a medium degree of temperature. But the climate of the empire is much varied, owing to the elongated shape of the country, which extends over nearly thirty degrees of latitude, to the great differences of altitude that characterize the surface of the land, and also to the action of a warm and a cold current that flow past its shores. Thus, in the northern part of Hokkaidō and in the Chishima Islands the snow never disappears, the sea freezes in winter, and sleet and fogs prevail. On the other hand, in the southern district, as well as in the Riukiū and Ogasawara groups, the heat is very great, and neither snow nor ice is seen in winter. In the central parts, again, the temperature varies according to the elevation of the land, and the configuration of the mountains and seas. As for Formosa, it is partly situated within the tropical zone, and the two extremes of the entire island are recorded to be 96° and 41° Fahrenheit. The warm ocean current, known as the Kuro-shiwo or Black Stream, from the deep somber color it displays in cloudy weather, rises from the distant Equator, and possesses an average temperature of 81° Fahrenheit in summer. Immediately after leaving the Equator it travels along the eastern coast of China, and thence passing northward, approaches the coast of Kiushū, where it bifurcates. The branch stream enters the Sea of Japan, and flows to the north; the principal stream passes by the southern coast of Shikoku and the main island, until it reaches the north of Cape Inubō in Shimōsa, where it again bifurcates, a branch turning northward, and the current itself traveling in a northeastern direction until it leaves the main island. In consequence, perhaps, of the heat received from this warm current, all the provinces of Kiushū, Shikoku, Sanyō-dō and Tōkai-dō seldom see snow. There is also a cold stream called the Oya-jiwo, of which the average summer temperature is as low as 37°. Its source is in the Sea of Okhotsk, whence it passes through the Kurile Islands, and flowing by Hokkaidō and the east coast of the northern section of the main island, reaches the neighborhood of Cape Inubō, where it disappears. Situated in a high degree of latitude, Hokkaidō and the northern part of the main island, being further exposed to the influence of this cold stream, have a severe climate. The snow lies there in masses for many days and the winter is long. The rainfall is heavy in summer and light in winter. It is greatest along the coasts washed by the Pacific Ocean and the Sea of Japan, and least in the central portions of the country along the two coasts of the Inland Sea, as well as in the northern end of the main island. Hokkaidō has an average fall.