Tables of temperatures of the sea at different depths beneath the surface : reduced and collated from the various observations made between the years 1749 and 1868, discussed / by Joseph Prestwich.

  • Prestwich, Joseph, 1812-1896.
Date:
1875
Catalogue details

Licence: Public Domain Mark

Credit: Tables of temperatures of the sea at different depths beneath the surface : reduced and collated from the various observations made between the years 1749 and 1868, discussed / by Joseph Prestwich. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    terranean ceased at a depth of 60 feet, and the annual variations at a depth of from 1150 to 1300 feet. At this point Aime found a uniform temperature ot 51 I, anc was of opinion, from the observations of Berard, that no increase took place at greater depths. This degree he showed to be the average of the mean temperature between Toulon and Algiers, of the months of January, February, and March. In order to determine whether the decrease of temperature was gradual, or whether the instrument passed through warmer strata, Aime also used a thermometer which was let down upright and reversed at the bottom of the soundings. Tins he termec a “ thermometre a retournement.” Besides these, Aime employed the ordinary selt- registering thermometer with an enlargement in one part of the tube to remedy t e inconvenience of the quicksilver passing over the index. These several, instruments were enclosed in copper cylinders strong enough to resist the pressure to which they were subjected. For moderate depths he preferred a glass tube hermetically sealed . In 1845 Captain (now Admiral) Spratt made 15 observations f from the surface to a depth of 1260 feet, in the Grecian archipelago, and obtained results m per ect accordance with those of Saussure and Aime in the Western Mediterranean. He afterwards made a more extended series of observations (34 in all) and to greater depths (7440 feet) in the eastern basin of the Mediterranean from Malta to Egypt +. - mira Spratt at first used Six’s thermometer; but finding that the index often moved he resorted, in shallow seas of the archipelago, to the plan of taking the temperature of the mud brought up from the bottom by means of a sound formed of iron tubing. This plan, Admiral Spratt considered, gave more reliable results than the other. In eveiy case m Forbes’s YILth zone, or between 1080 and 1200 feet, the mud indicated a temperature of 55°-5 • and he concluded that there was no reason to suppose the temperature to be lower than 55° at any depth under 1800 feet. In the deeper waters he reverted to the use of Six’s thermometer. , Captain (now Admiral Sir Edward) Belcher gives a series of eight observations he made in mid-Atlantic when crossing the equator in 1S43, at depths of from 1800 t0 6000 feet 6. Sir Edward informs me that a much larger number were made, but la thev were not published at the time and have been unfortunately lost, with the exception of the few others recorded by Sir James Koss||. Sir Edward Belcher also mentions that he had a water-bottle of great strength, with two enclosed thermometers specially made by Carey, and that these instruments “were tested continuously between 18oo and 1846, and never found to vary from each other or from the standaid which [Sir E. B.] now possess, and which belonged to the Old Board of Longitude. They * For a description of his instruments see op. cit. Ann. Chim. et Phys. pp. 6-12. + Phil. Mag. for 1848, p. 169. . , , , ,, + The Nautical Magazine for 1862, p. 9. Admiral Spratt has also obligingly communicated to me twenty-two unpublished observations to which is attached “ u ” in the Tables. § Narrative of the Voyage of H.M.S. ‘ Samarang ’ during the years 1843-46. London, 1848, vol. i. p. •