Page:Collier's New Encyclopedia v. 08.djvu/365

LEFT SEA 309 SEA whole ocean is estimated at 315,000,000 composition of 1,000 cubic centimeters of cubic miles. sea water: Temperature. — The temperature of • ■. ,_, aj OD _ nc. the surface waters of the ocean varies Sg^SKwSriK V.'. .WW: "'obIs from 28 F. in the polar regions to 85 Magnesium sulphate 1.7 (5«5 or 86° in equatorial regions. In many Calcium sulphate 1.34 25 places the surface layers are subject to Malnls^ S brom!dI W. .V.'..'. 0.8809 great annual changes due to the seasons Calcium carbonate 0.1287 and the direction of the wind. The tern- Water 989.7073 perature of the water at the bottom of 1027.0000 the ocean over the abysmal areas ranges from 32.7° F. to 36.8° F. The great Each base is probably in combination mass of the ocean consists of cold water with each acid, so that there are really — i. e., of water below 40° or 45° F.; at 16 salts altogether from the mixture of a depth of little over half a mile the the four bases and four acids. The total water in the tropics has generally a amount of sea salts may vary greatly in temperature below 40° F. In the open different samples of sea water, but it has ocean the temperature usually decreases been shown by hundreds of carefully con- as the depth increases, the coldest water ducted experiments that the ratio of the being found at the bottom. In inclosed constituents of sea salts is nearly every- or partially inclosed seas, cut off by bar- where constant, with one significant ex- riers from the great ocean basins, the ception, that of lime, which is in slightly temperature remains uniform from the greater proportion in the water from the height of the barrier down to the bottom; deeper parts of the ocean basins. Nitro- for instance, in the Mediterranean the gen remains at all times and places nearly temperature is about 56° from 200 constant; not infrequently the propor- fathoms down to 2,000 fathoms. tion of oxygen is much reduced in deep Circulation. — The circulation of oceanic water, owing to the process of oxidation waters is maintained by the action of the and respiration. Carbonic acid free or prevailing winds and by other causes, loosely combined is abundant, and plays In the oceanic areas the prevailing winds a most important role in the economy are governed by the large anticyclonic of the ocean, combining with and render- areas situated toward the centers of the ing soluble normal carbonates of lime north and south Atlantic and north and and magnesia to solution in the form of south Pacific. The winds blow out from bicarbonates. Water, as is well known, and around these anticyclonic areas. For is but slightly compressible, and almost instance, in the Southern Hemisphere the any substance that will fall to the bot- warm salt water of the tropical regions torn of a tumbler of water will in time is driven to the S. along the E. coasts fall to the bottom of the deep ocean, of South America, Africa, and Australia, Still the compressibility of water must till on reaching a latitude of between 50° not be neglected in oceanographical ques- and 55° S. it sinks on being cooled and tions. In the deeper parts of the ocean spreads slowly over the floor of the ocean the pressure amounts to four or five tons to the N. and S. A similar circulation per square inch; hence, in an ocean with takes place in the northern hemisphere, a depth of 5 miles, were the action of though much modified by the peculiar gravity suddenly to cease, the ocean configuration of the land masses; for in- waters would rise 500 feet above their stance, the cold salt water at 30° F. present level from expansion, which occupies the deeper parts of the Life. — The color of pure sea water is Arctic basin is largely made up of the a light shade of blue; it has, however, dense Gulf Stream water, which sinks frequently various shades of green and to the bottom on being cooled in the Nor- brown, owing to the presence of organisms wegian Sea. The water evaporated from and matters in suspension. It has been the sea surface is borne to the land masses definitely established that life in some and condensed on the mountain slopes, of its many forms is universally distrib- The saltiest waters are found in the re- uted throughout the ocean. It has long gions of greatest evaporation; for in- been known that marine plants and ani- stance, in the Red Sea, Mediterranean, mals abound in the shallow waters sur- and in the trade-wind regions of the rounding continents and islands. Algse great ocean basins. disappear from the sea-bed at depths Composition of Sea Water.— It is prob- between 100 and 200 fathoms, but a great able that every element is in solution in abundance of animals have been procured sea water, the great majority, however, in the greater depths. The term 'Ben- present only in exceedingly minute traces, thos" is now used for all the animals and If the average density of sea water be plants which live attached to or creep taken at 1,027, pure water being 1,000, over the bottom of the ocean, "Plankton then the following would represent the being the term for all the plants and am-