604 
ME. J. PRESTWICK ON SUBMARINE TEMPERATURES. 
and the mention of them approvingly by Pouillet* and ARAGof, I cannot find that they 
were again used, although a modified form contrived by M. Aime was employed by him 
in his researches in the Mediterranean in 1840-44. 
In 1838 a few observations were made in the Indian Ocean by the Rev. J. H. Pratt J. 
An American expedition made the round of the world in 1839-42 under the command 
of Captain Wilkes, who gives twenty-eight § deep-sea temperatures at depths of from 
60 to 5100 feet in the South Pacific and Southern Oceans, in one case recording 
a temperature of 27 0, 5 at a depth of 1420 feet in the latter sea. The subject was 
afterwards [| further discussed by Captain Wilkes in a separate paper, in which he 
expressed an opinion that there existed a zone of the uniform mean temperature of 
39 0- 5 Fahr. It would appear that Six’s thermometers without protection were used. 
In the same year (1839) a very important expedition was despatched from this country 
to the Antarctic seas under the command of Captain Sir James C. Ross. A special 
code of instructions was drawn up by a Committee of the Royal Society. Numerous 
results of great value were obtained, especially those relating to the soundings and sea- 
bed of the Antarctic Ocean. As many as 161 deep-sea temperature-observations are 
recorded, chiefly in the Southern and Antarctic Oceans, with a few in the Atlantic and 
Indian Oceans % They vary in depth from 12 to 7200 feet; some of the soundings 
were much deeper. 
These temperature-soundings claim particular notice in consequence of the undue 
weight which has been attached to them. In starting Sir James Ross took with him 
a supply of Six’s thermometers ; but he gives no description of how they were used, or 
what precautions were adopted **. The observations also are not tabulated, but are 
scattered through the work without plan or order ; and it is at times difficult to fix 
on their exact position, date, &c. It would appear that, owing to want of protection 
and the great depths at which they were used, all the instruments he took with 
him from England were broken by the time he reached the Southern Ocean. 
* Elements de Physique, 5th edit. vol. ii. p. 653. f (Euvres completes, vol. mi. p. 626. 
t London and Edinb. Phil. Mag. 1840, vol. xvi. p. 176. 
§ United States Exploring Expedition, 1839-42. London, 1845, vol. i. pp. 137, 139, 230, 309, 310 ; 
vol. ii. pp. 290, 293, 299, 332 ; and vol. iii. Appendix I. 
|| “ On the Depth and Saltness of the Ocean,” American Journal of Science and Arts for January 1848, p. 41. 
*[[ A Voyage of Discovery and Research in the Southern and Antarctic Regions. London, 1847, vol. i. 
pp. 34, 130, 166, 167, 168, 170, 180, 200, 222, 231, 267, 280, 306, 309, 313, 317, 321 ; and vol. ii. pp. 35, 
52, 53, 55, 133, 138, 140, 141, 147, 156, 193, 195, 200, 214, 216, 227, 228, 282, 322, 351, 356, 358, 363, 
369, 374, 379, 382, 384. 
** Dr. Hooker, who accompanied the expedition, informs me that no precautions were taken against pressure, 
hut that to prevent breakage “ the thermometers were enclosed in a copper cylinder. Sometimes two thermo- 
meters were placed at different points of the same line (say 500 and 1000 fathoms), at others the line was 
drawn up and sunk again to a greater or less depth. The first fathoms of the line were spun yarn, the next of 
3 plies of the same, the rest whole line.” It was hauled in by the whole ship’s company. Dr. Hooker also says 
“ that the average length of time, speaking entirely from memory, during which the thermometers were left at 
the depths reached was a quarter of an hour.” 
