ME. J. PRESTWICK ON SUBMAEINE TEMPERATURES. 
607 
were out in 1852-54, exposed to all the Arctic variations of temperature, and are still 
perfect. They were made to go inside the water-bottle, and not subjected to jerks of 
the line, which we found often moved the indices”* * * § . 
In 1845-51 Captain Kellett, in his voyage f to the Pacific and Behring Strait, made 
38 observations to depths of 3000 feet, several of them serial, some in mid-Atlantic, 
others in the Pacific, ranging from near the Equator to Behring Straits, and seven in 
the Arctic Ocean beyond. Six’s thermometers without protection were used. 
Lieutenant (afterwards Commander) Dayman, who served on the surveying-ship 
‘ Rattlesnake,’ made a series of one hundred and ten observations in the Atlantic, 
Indian, and Southern Oceans, at depths generally of from 1000 to 2000 feet J. 
While the readings given by other observers who used unprotected self-registering 
thermometers agree fairly well among themselves, those recorded by Dayman are much 
higher in proportion. But as he gives no particulars of his instruments, or of the mode 
in which they were used, it is- not possible to say how the difference arises or what the 
error may be ; it seems uniformly too high by 1° or 2°. There are also anomalies in 
the lists, which leads me to suppose that the readings of the lesser and greater depths 
have sometimes been transposed. The readings, however, have a certain independent 
value inter se as furnishing comparative temperatures at corresponding depths. 
Sir A. Armstrong §, who was with Captain M c Clure on his memorable voyage along 
the coast of Arctic America, records three observations made on the voyage out round 
Cape Horn, and three in the Arctic Ocean after passing Behring Strait. No mention 
is made of the thermometers, except that they were Six’s “ self-registering.” 
In the series || of “Reports” to the Government of the United States much valuable 
information is given with respect to the temperature of the seas off the North-American 
coast, and especially of the Gulf-stream at various depths. As the original observations 
are, however, not recorded, but only the diagrams founded on them, I am unable, with 
two or three exceptions, to give any tabulated details, and must refer to the “ Reports ” 
themselves for fuller information. Owing to the depth of the Gulf-stream off the 
American coast, the lines of bathymetrical isotherms lie at very variable depths. The 
* With respect to the mode of conducting the observations. Sir Edward Belcher says, “ The deep-sea tem- 
peratures were observed only in calms. The thermometers were all handled by myself, and eased overboard 
with the greatest care. The hauling-in was not subject to jerks, as it was done by the aid of a boat astern, 
the ship drifting by currents, sometimes one to two hundred fathoms from the boat, and great caution observed 
in getting them detached (by myself) and read off instantly.” 
t Yoyage of the ‘Herald,’ Captain Kellett. By Berthold Seehan. London, 1853, vol. i. pp. 7, 92, 94, 
vol. ii. p. 107. 
+ Narrative of the Yoyage of H.M.S. ‘ Rattlesnake,’ Captain Stanley, 1846-50. By John Macgillivray. 
London, 1852. Appendix I. vol. i. ; and Edinb. New Phil. Journ. for 1852, vol. lii. p. 267. 
§ A Personal Narrative of the Discovery of the North-West Passage, by Alexander Armstrong, M.D., 
R.N., H.M.S. ‘ Investigator,’ Captain M c Clure, 1850-54. London, pp. 19, 43, 65, 150, 216. 
|| See Report of the Superintendent of the United States Coast Survey for 1854, by Professor Bache. 
Also those for succeeding years. 
