The Atlantic Ocean: north and south
Carruthers, J.N. (1961). The Atlantic Ocean: north and south, in: Borgstrom, G. et al. (Ed.) Atlantic Ocean fisheries. pp. 1-17
In: Borgstrom, G.; Heighway, A.J. (Ed.) (1961). Atlantic Ocean fisheries. Fishing News (Books): London. VIII, 336 pp., meer
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| Abstract |
In presenting a popular article such as the folIowing is supposed to be, the writer cannot assume on the part of his readers any acquaintance with the techniques and instruments ernployed by those who carry out scientific studies of the oceans. Neither can he take it for granted that his readers wi1l necessarily have much acquaintance with the main features of the ocean waters-such as their depths, currents, chemistry , etc. Because there is no justification for prefacing the article with a sort of minor treatise on oceanography, it may be useful to set down at the outset, a few remarks intended to be helpful. The reader must accept that oceanographers have ways and means of finding out with great accuracy what are the temperatures in place of the deepest waters, and of bringing up water samples frorn all levels in the seas for submission to precise analysis. He must also accept (without being told how), that it is nowadays possible to bring up samples of the ocean floor from the greatest depths, and equalIy possible to obtain cores of the sea bed frorn the abyss. He must also understand the oceanographers have powerful means of measuring currents not only on the surface of the seas but also on their beds, of measuring waves by use of electronic instruments actually built into research vessels, and of determining the depths of the oceans by new precision echo-sounding machines which greatly excel those about which he may have read something in newspapers and the popular press. Reference is made in what folIows to the fact that photographs of the Atlantic Ocean bed have been taken at a depth of 24,600 feet, and it is now known that the same has been done in the deepest spot of the Atlantic beneath some 5½ miles of water. It is moreover possible to tow on the ocean bed sledges frorn which cinema films can be taken. Because of the very great diversity of types of bottom we have not included any seabed photographs in this article. In particular the reader must accept that the main labelIing characteristic of sea water-its degree of saltness known as "salinity"-can be determined with very great precision indeed both chemicalIy and electricalIy. Tbis latter point is made because we shalI often speak of salinity, the numerals expressing which denote how many parts of total salts by weight are contained in a thousand parts by weight of the water. The expression "total salts" is used to convey that not all the salt in the sea is the common salt known as sodium chloride. The numerals denoting salinity being (as just said in effect) tenths of percentages, are folIowed by the symbol °/°° not to be confused with %. |
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