OCEAN

(Gr. uixtavof.) In Geography, the vnst body of water which surrounds the continents, and is the receptacle of all their running waters. It is divided by geographer? Into Ave great basins, viz., the Pacific Ocean (so called by reason of its comparative stillne ), which separates Asia from America, and is the largest of all the basins; 2, the Atlantic Ocean, which has Europe and Africa on its eastern shore, and America on its western; 3, the Indian Ocean, which washes the south of Asia, and the Routh-eastem coast of Africa; 4th, the Arctic Ocean, which surrounds the north pole; and 5, the Antarctic, which surrounds the south pole. Other smaller portions of the great connected body of water are called seas, of which the Mediterranean, the German, the Baltic, and Black sea?, are the most considerable.The superficial extent of the several great basin* is not known with any certainty, nor, Indeed, can their limits he exactly defined. From the nearest estimation that can be made of the extent of the continents and principal islands, ii i e are covered by water. The Pacific Ocean alone exceeds the whole surface of the dry land. Depth of the Ocean. — If the superficial extent of the ocean cannot be easily ascertained, it will readily be supposed that Its depth is a problem of much greater difficulty. The bottom appears, wherever it has been reached by the sounding line, to have similar inequalities to those of the surface of the land: hence the depth must be extremely various; nnd it might be supposed from analogy that the greatest depth of the ocean is at least equal to the height of the highest mountains above its surface. Lord Mulgrave found no bottom in the North Atlantic Ocean with a sounding line of 4680 feet; and Mr. Scores by sounded to the depth of 7200 feet, without the lead touching the ground. These experiments are not altogether to be depended on for the determination of such great depths; for, the pre ure becoming verv great, the lead may be drawn out of the perpendicular direction by currents, of which it may encounter more than one, flowing in different directions. Over a great portion of the Atlantic and Pacific Oceans no bottom has been found. The depth of the ocean, in general, and the form of the bed on which it rolls, cannot, therefore, lie determined by experiment. The mathematical theory of the oscillations of fluids has, however, thrown some light on the subject. Laplace demonstrated that the difference which is indicated by observation between the height of two consecutive tides depends on the law of the depth of the sea, and that, but for the influence of acce ory circumstances, it would disappear altogether if the depth were constant. It follows, therefore, that, since the difference between the consecutive tides Is extremely small, the depth of the sea, taking in a large extent of ocean, must be nearly uniform; that is to say, there must be a certain mean depth from which the variations are not considerable. (JYfec. Celeste, book xiii.) Level of the Ocean. — Were it not for the disturbing actions of the sun and moon, and of the winds, the level of the ocean would be everywhere the same-, and its surface would have the form determined by the attraction of the whole ma of the earth, combined with the centrifugal [s. 859]