OF THE POLAR SEA. 15 
bottom. The register thermometer was attached 
to the line just above the lead, and is supposed 
to have descended six hundred and fifty fathoms. 
A well-corked bottle was also fastened to the 
line, two hundred fathoms above the lead, and 
went down four hundred and fifty fathoms. The 
change in temperature, shewn by the register 
thermometer during the descent, was from 52° to 
40.5; and it stood at the latter point, when 
taken out of the tin case. The temperature of 
the water brought up in the bottle was 41°, being 
half a degree higher at four hundred and fifty 
than at six hundred and fifty fathoms, and four 
degrees colder than the water at the surface, 
which was then at 45°, whilst that of the air 
was 46°. This experiment in shewing the water 
to be colder at a great depth than at the surface, 
and in proportion to the increase of the descent, 
coincides with the observations of Captain Ross _ 
and Lieutenant Parry, on their late voyage to 
these seas, but is contrary to the results obtained 
by Captain Buchan and myself, on our recent 
voyage to the north, between Spitzbergen and 
Greenland,. in which sea we invariably found the 
ought from any great depth to be warmer 
than that at the surface. | 
On the 28th we tacked, to avoid an extensive 
stream of sailing ice. The temperature of the 
