ATLANTIC OCEAN

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ATLANTIC OCEAN ; the mass of water between the western coast of Europe and Africa, and the eastern coast of America; the only considerable aquatic communication between the polar extremities of the earth, if we do not give to both its extremities the name of the Frozen ocean. The name is derived from Atlas, (q. v.) The Atlantic, in its narrowest part, between Europe and Greenland, is upwards of 1000 miles wide, and, opening thence to the S. W. with the general range of the bounding continents, spreads, under the northern tropic, to a breadth of 60 degrees of longitude, or 4170 miles, without estimating the gulf of Mexico. Beyond the torrid zone, the A. inflects to the N. W. and S. E., again complying with the bearing of the adjacent continents, which correspond with great exactness to each other. The A. and its gulfs occupy about the seventh part of the superficies of the globe, curving round the western, southern and northern part of the eastern continent, from 72° N. lat. to 35° S. lat, or through 107 degrees of latitude. This immense strait is limited, on the west, by the most lengthened landline, extending north and south, that can be drawn on the earth. " When we cast an eye over the Atlantic," says Humboldt, in his Personal Narrative, " or that deep valley which divides the western coasts of Europe and Africa from the eastern coasts of the new continent, we distin guish a contrary direction in the motion of the waters. Between the tropics, especially from the coast of Senegal to the Caribbean sea, the general current, that which was earliest known to mariners, flows constantly from east to west. This is called the equinoctial current. Its mean rapidity, corresponding to different latitudes, is the same in the Atlantic and Southern oceans, and may be estimated at 9 or 10 miles in 24 hours; consequently from 59 to 65 hundredths of a foot every second of time." This great observer also says, "In comparing the observations which I had occasion to make in the two hemispheres, with those which are laid down in the Voyages of Cook, la Perouse, d'Entrecasteaux, Vancouver, Macartney, Krusenstern and Marchand, I found that the swiftness of the general current of the tropics varies from 5 to 38 miles in 24 hours, or from one third of a foot to one and two tenths per second." The western equinoctial current is felt, though feebly, as high as 28° N. lat., and about as far south, though it must be in excess along the equator. The eastern salient point of South America being in upwards of 6° S. lat., the great mass of ocean flood is unequally divided. South from cape St. Roque, the current is turned down the coast of South America, and, between 30° and 40° S. lat., reacts towards Africa. North from cape St. Roque, the coast of South America bends to a general course of N. 62° W., and, with the Caribbean sea and the gulf of Mexico, maintains that direction to the mouth of the Rio Grande del Norte, 2560 miles. Along this coast, the equinoctial current is inflected northward, and augmented by constant accumulations from the east; the whole body pouring through the various inlets between the Windward islands of the West Indies into the Caribbean sea, and thence, between Cuba and Yucatan, into the gulf of Mexico. In the latter reservoir, it has reached its utmost elevation, and again rushes out into the A. through the Cuba and Bahama or Florida channel, and, sweeping along the coast of the U. States and Nova Scotia, to about 50° N. lat., meets the Arctic currents from Davis's straits, and, from the Northern Atlantic ocean, is turned towards Europe and the northwest of Africa, and is finally merged in its original source within the tropics. To this oceanic river has been given the name of gulfstream. It is the second most extensive and much the most strongly marked whirlpool on the globe, having an outline of about 15,000 miles. The mean motion of the gulfstream is, no doubt, changeable, even at the same points. The time of its periodical revolution is about 2h years, and the maximum of motion in the Bahama channel. Humboldt notices this phenomenon thus :" In the Florida channel, I observed, in the month of May, 1804, in the 26th and 27th degrees of latitude, a celerity of 80 miles in 24 hours, or 5 feet every second, though at this period the north wind blew with great violence. At the end of the gulf of Florida, in the parallel of cape Cannaveral, the gulfstream, or current of Florida, runs to the N. E. Its rapidity resembles that of a torrent, and is sometimes five miles an hour." (For further information on this subject, see the article Current, and also Darby's View of the United States, Philadelphia, 1828.) Humboldt endeavored to ascertain the comparative height of the waters of this ocean along its shores, and that of the Pacific on the opposite side of the isthmus, taking the level of the gulf of Mexico as a standard. He found the surface of the former to be 6 or 7 metres higher than that of the latter (19 or 22 feet, English measure). The depth of the A. is also extremely various, in many places being wholly beyond the power of man to fathom. Captain Scoresby, in the Greenland sea, in 1817, plumbed to the greatest known depth which a line has reached, i. e. 7200 feet. Many parts of this ocean, however, are thought to be much deeper.The saltness and specific gravity of the A. differ in various parts, and gradually diminish from the equator to the poles. In the neighborhood of the British isles, the salt has been stated at o3*9 th of the weight of the water; and, according to doctor Thompson, the proportion of saline contents does not appear to differ much, whatever may be the latitude in which the water is examined. The variation resulting from all the observations of Pages, Phipps and Baume, is from 0.0451 to 0.35 saline matter. The temperature of the A. is highest between 5° 45' and 6° J 5' N. lat., where it has been found, by actual observation, to vary from about 82° 5' to 84° 5' of Fahrenheit. Peron and Humboldt give several interesting results of their observations. The currents and the masses of ice which go from the north, in the general current, tv the equator, change the temperature of the water very much. Fragments of these icebergs occasionally reach the 40th degree of latitude. In the months of Juno and July, they add much to the danger of a passage between North America and England. We do not know that there exists an exact comparison of the natural history of the A. with that of other oceans.