MEDITERRA'NEAN SEA, so named from its being almost entirely iucloed by the •continents of Europe, Asia, and Africa, one of the greatest inland ,seas in the world, -extends (inclusive of the sea of Marmora, but exclusive of the Black sea and sea of Azof) to about 1,000,000 sq. miles. Its length, from e. to w., is about 2,32b m., its greatest breadth about 1080, but it is divided into two great basins by the approach of the Euro peen and African coasts in its middle. It is connected with the Atlantic ocean only by the straits 6f Gibraltar, through which a strong current continually' flows into the Medi terranean. Another strong current also flows into it from the Black sea, which receive:.;. large supplies of fresh water, whereas the great rivers which fall into the Mediterranean, itself are comparatively few; the principal tieing the Ebro, the Rhone, and the Po, front ' Europe; and the Nile, from Africa. It receives no large river from Asia. The evapora tion from the surface of the Mediterranean is, on the contrarv, greater than what takes - place in the ocean generally, owing to the heat which proceeds from the African deserts, and the shelter which mountains afford from the cold winds of the north. The iurface temperature, dependent on the intensity of solar radiation, is in summer about 5° above that of the Mediterranean. By the expeditions for the scientific exploration of the deep sea in 1869 and 1870 it has been ascertained that the effects of this surface-heatinm are limited to a depth of 100 fathoms; at every depth beneath this, even down to 190efath oms, the temperature of the 3iediterranean, unlike that of the Atlantic, is uniform, aud stands about 54° or 55°. This is, in fact, the winter temperature of the entire contents. of the basin, from the surface downwards, and also the mean temperature of the crust of" the earth in that region. In winter the temperature of the Mediterranean and the Atlan tic approximate very closely. In consequence, probably, of the greater evaporation, the water of the Mediterranean, unlike that of inland seas in general, contains about. one-sixth per cent more salt than the Atlantic ocean. Its specific gravity is alinost every where greater than that of the Atlantic, being in the proportion of 1.0386 to 1.0283. Its. color, when undisturbed, is a bright deep blue; but in the Adriatic a green, and in the Levant a purple tinge prevails, while the dark hue of the Euxine is indicated in its name of "Black sea." Different parts of the Mediterranean sea bear different naines—as the JEgean sea, the Ionian sea, the Adriatic sea, or gulf of Venice, etc. Its northern COaSt is very much broken with bays and peninsulas, and abounds in harbors, affording the inhabitants of the south of Europe great advantages for commerce, of which the Medi tenanean sea was the chief seat during all periods of history, till toward the close of the middle ages, when, after the invention of the mariner's compass, a spirit of maritime adventure sprung up, and the discoveries of the Portuguese and of Columbus led to the extension of commerce over the whole world. The commerce of the Egyptians, the
, Phenicians, the Greeks, and Romans, was almost entirely confined to the Mediterranean. sea.
The depth of the Mediterranean sea is generally greatest in its western basin. In, many places it is 3,000 ft. deep. Near Nice it is 4,200 ft. deep at a distance of only a few yards from the shore. In many places it is 5,000 ft. deep and more. The depth in the straits of Gibraltar is about 5,500 feet. It is highly probable that the coasts of Europe and Africa were once united here, and have been separated by some great con vulsion; it is also supposed that land once stretched from Sicily to cape Bon in Africa, where now a ridge exists along which there is for the most part a depth of scarcely 200 ft., and in some places of little more than 40 ft., whilst on each side, at a short distance, the depth is more than 6,000 feet. The Mediterranean see is subject to the w., n., and n.e. winds for more than two-thirds of the year, while in spring the s.e. and s.w. winds prevail. The most formidable of those winds which are peculiar to the Mediterranean sea is the sokow or levanter. In the gulf of Venice the greatest tides rise about 3 ft., and, in the Great Syrtis, 5 ft., but in most places the tides are scarcely observable. According to the measurements of Napoleon's Egyptian expedition (1799) the surface of the Mediterranean sea, in the neighborhood of Alexandria, was from 24 to 30 ft. lower than that of the Red sea at Suez; but more recent measurements have shown that the difference of level is inconsiderable, and that the mean level of the Red sea is at most 6 in. higher than the 3Iediterranean.
Of the 643 specie§ of European sea-fishes, 444 inhabit the Mediterranean sea, some of vvhich are peculiar to it. It has a greater number of species than the British and Scandinavian seas, but does not nearly so much abound in useful kinds. Tunny-fishing.; is extensively prosecuted on some parts of its coasts. It is rich in red coral, which is procured in great quantity on the coasts of Provence, of the Balearic Isles, and of Sicily, but particularly on the coasts of Bona and Barca in Africa.
••• The shores of the Mediterranean sea are in many parts subject to frequent earth quakes. Besides the existing active volcanoes of Etna, Vesuvius, and Stromboli, there are many evidences of recent volcanic action, and instances have occurred of islands suddenly upheaved by it, where volcanic fires have appeared for a short time.