592 
ME. J. PEESTWICH ON STJBMAEINE TEMPEEATUEES. 
them in the Tables. The general conclusion Phipps and Ieving drew was that, except 
in Arctic seas, the temperature decreased with the depth. 
In 1780 Saussuee made the two first observations on the temperature of the Medi- 
terranean* — one off Genoa at a depth of 944 feet, and the other off Nice at a depth of 
1918 feet. Both the thermometers marked 55°'8, or, allowing his correction, about 
55° - 5, a singularly close approach to the more recent observations of Aime and others. 
Saussuee used a spirit-thermometer of Reaumue’s with a large ball, which he surrounded 
with a mixture of wax, resin, and oil 3 inches thick ; and the whole was then placed 
in an iron-wire cage. In both cases he sunk the thermometers at 7 o’clock in the 
evening, and left them down until 7 in the morning, so that they might acquire precisely 
the temperature of the surrounding water. The one sunk 1918 feet deep took twenty- 
four minutes to haul in, and he inferred that this would give the true temperature 
within a fraction (one fifth) of a degree. The thermometer was specially made and 
graduated for the experiment ; and he had previously ascertained that after lowering it 
to a temperature of 2°'3 R., and arranging so that by constant moving it traversed 
1000 feet of water at 14° R. in ten minutes’ time, the instrument had only risen one 
tenth of a degree, or to 2 0- 4. 
In 1800-4 a voyage of circumnavigation was undertaken by command of the Emperor 
Napoleon. Monsieur F. PEEOisrf accompanied it as naturalist and physicist; but, owing 
to the indifference of the officers and ill-will of the men, he was unable to make more 
than 4 uncertain experiments, all in the tropical seas, and at depths only of from 320 to 
2270 feet, the lowest temperature recorded being 45°-5 in lat. 4° N. M. Peeoh, not 
satisfied with former methods, employed a mercurial Reaumue’s thermometer, placed in 
a glass cylinder, with cotton-wool to protect it. This was enclosed in a wooden cylinder 
sufficiently large to allow of a packing between the two of powdered charcoal, and then 
put in a tin case, which was wrapped round with oil-cloth. The value of the results to 
be obtained by such protected instruments necessarily depends, as in the case of Saus- 
suee’s experiments, upon leaving the thermometer down for some hours ; but in one 
case only was M. Peeon allowed to leave his apparatus down 1 hour 50 minutes, and 
once he had to haul it up after five minutes’ submergence. Peeon refers to and 
tabulates the experiments of his predecessors, and remarks on the same law of the 
temperature decreasing from the surface downwards. 
In 1803 the ‘Neva’ sailed on .a voyage of circumnavigation, under the command of 
Captain Keusensteen. Touching at Falmouth, he passed round Cape Horn to the Sand- 
wich Islands, Kamtschatka, Japan, and back by the Cape of Good Hope. Keusensteen 
took out with him an apparatus made in St. Petersburg on the model of Hales’s; but this 
was abandoned for Six’s self-registering thermometer, which, although invented in 1782, 
was now for the first time employed at sea. Some thirty experiments were made by 
* Voyages dans les Alpes. Neufchatel, 1796, yol. iii. pp. 153 & 196. 
t Voyage de Decouvertes aux Terres Australes en ] 8Q0-4, redige par M. F. PLeox, Nat. de PExped. Paris, 
1816, pp. 334-37. 
