Sir John Herschel gives to the winds the entire right of setting the ocean streams in motion ; Lieutenant Maury holds the universal circulation of the sea to be caused by nothing else than the difference in its specific gravity ; and Dr. Carpenter (or rather Professor Buff) would bring about a general interchange of polar and equatorial water by the aid of sunshine and frost alone.
These two facts, taken together, tend to show that large currents of warm water have their genesis in the Indian Ocean. One of them is the well-known Mozambique current, called at the Cape of Good Hope the Lagulhas current, which skirts the coast of Natal. Another of these warm currents from the Indian Ocean makes its escape through the Straits of Malacca, and, being joined by other warm streams from the Java and China Seas, flows out into the Pacific between the Philippines and the shores of Asia. Thence it attempts the great circle route for the Aleutian Islands; tempering climates, and losing itself in the sea as its waters grow cool on its route towards the north-west coast of America. Near the shores there is a counter-current of cold water.
There is sometimes, if not always, another exit of warm water from the Indian Ocean. It seems to be an overflow of the great intertropical caldron of India ; seeking to escape thence, it works its way polarward more as a drift than as a current. It is to the Mozambique current what the northern flow of warm waters in the Atlantic is to the Gulf Stream. This Indian overflow is very large. The best indication of it is afforded by the sperm whale curve. In shore of, but counter to, the black stream,' along the eastern shores of Asia, is found the cold current of Okhotsk, a streak or layer or current of cold water answering to that between the Gulf Stream and the American coast. This current, like its fellow in the Atlantic, is not strong enough at all times sensibly to affect the course of navigation, but, like that in the Atlantic, it is the nursery of most valuable fisheries. The fisheries of Japan are nearly as extensive as those of Newfoundland, and the people of each country are indebted for their valuable supplies of excellent fishes to the cold waters which currents of the se bring down to their shores. There are also abou the equator in this ocean some curious current which Maury called the doldrum currents of th Pacific, but which he says he does not understand and as to which observations are not sufficier yet to afford the proper explanation or description There are many of them, some of which at tim( run with great force. On a voyage from th Society to Sandwich Islands, Lieutenant Maur encountered one running at the rate of ninety-si miles a day. These currents are generally foun setting to the west. They are often, but m always, encountered in the equatorial doldrun on the voyage between the Society and tl Sandwich Islands. The Pacific Ocean and tl Indian Ocean may be considered as one sheet water, covering an area quite equal in extent one-half of that embraced by the whole surfal of the earth. There is also at times another war current running to the south midway betweE Africa and Australia, of which the whales gi' indications. These convey immense quantities highly saline water, which has to be replaced 1 colder water. The Aleutian Islands are in tl
tract of the current from the Straits of Malacc They are as subject to fogs and mists as the ban of Newfoundland. No trees grow on them, am for all household purposes the natives depend ( the drift - wood, amongst which camphor and woods of Japan and China are often seen.
The Japan Stream, known as the Kuro-Siw sweeps along the outer or eastern shores of tl Japanese Islands. This stream carries with it tl gulf-weed or Sargossa, with many animal fora such as Clio, Cavolina, Pteropods, Spiriali Atlanta, and the Pelagian skeleton shrimps, Alin and Erichthys ; also the carapaces of the sailo crab called Planes. Near Japan a current ru in a thin layer in shore similar to that betwei the Gulf Stream and the American coast, and, li] it, is the nursery of many valuable fisheries. It in the cold waters which the currents of tl ocean bring to its shores that the people of Japt obtain their supplies of fish, there as abundant those of Newfoundland.
The great equatorial current of the Pacifi when it reaches the south end of Formosa, pass off into the China Sea, while the other part deflected to the northward along the eastern cos of Formosa until reaching the parallel of 26° when it bears off to the northward and eastwar washing the whole S.E. coasts of Japan as far the Strait of Tsugar, and gaining in strength as advances. This is called the Kuro-Siwo, or Jap Stream ; and near its origin this stream is co: tracted, and is usually confined between Formo and the Meiaco-Sima group of islands, with width of nearly a hundred miles ; but to t northward of the latter it rapidly expands on 1 southern limit, and reaches the Loo-Choo and Bon Islands, attaining a width to the northward of t latter of about 400 miles. Its average maxim temperature is 86°. The N.W. edge of the strew is strongly marked by a sudden thermal than, in the water of from 10° to 20°, but the S. am E. limit is less distinctly defined, there being gradual thermal approximation of the air al water. Along the borders of the stream, where chafes against the counter-currents and torp waters of the ocean, as also in its midst, who whirls and eddies aro produced by islands the inequalities in its bed, strong tido rips are encountered, often resembling heavy breakers on reefs or shoals. Its average velocity, between the south end of Formosa and Tsugar Strait, has been found to be from 35 to 40 miles in 24 hours. Off the Gulf of Yezo, its maximum strength is recorded as high as 72, 74, and 80 miles respect ively on three successive occasions ; but local causes give rise to changes in its velocity and its direction. To the northward of lat. 40° N., in lung. 143° E., there is a cold counter-current intervening between this stream and the south coast of Yezo, as shown by the sudden thermal change of the water from 16° to 20°, which it is believed sets to the westward through the Strait of Tsugar. The waves of the ocean vary in height, but rarely rise over 16 feet above the level. In the Indian Ocean, the tide follows the moon to the west with a somewhat northerly course.— Maury's Phys. Geo. ; Maury, United States Sail ing Directions ; lYilson's Science of Shipbuilding; Adams, pp. 240, 318 ; Horsburgh; Captain Taylor ; Ileathcote ; Tennant's Ceylon ; Findlay ; Buist.