CHAP. VI. | DEEP-SEA TEMPERATURES. 301 
that these observations were made with registering 
thermometers guarded somewhat in the same way 
as those which we employed in the ‘ Porcupine.’ 
There is almost sufficient internal evidence that the 
mode of protecting these thermometers must have 
been satisfactory, for the temperatures at the greatest 
depths are such as might have been expected from 
Miller-Casella thermometers. Unguarded  instru- 
ments would certainly have given higher indica- 
tions. 
The last of the observations quoted, a considerable 
way up Davis’ Strait, is of great interest. The tem- 
perature of the surface of the sea was nearly a 
degree and a half Centigrade above that of the air, 
and the temperature of the water was altogether 
unusually high. It is now well known that at 
certain seasons of the year a very marked extension 
of the Gulf-stream passes into the mouth of the 
Strait. The isotherms for September and July are 
shown on the chart from data kindly procured for 
me by Mr. Keith Johnston. 
Sir Edward Sabine, in an extract from his pri- 
vate Journal of Sir John Ross’s voyage quoted by 
Dr. Carpenter,’ gives a lower temperature than any 
hitherto recorded. He says: ‘“‘ Having sounded on 
September 19th, 1818, in 750 fathoms, the regis- 
tering thermometer was sent down to 680 fathoms, 
and on coming up the index of greatest cold was 
at 25°75 Fahrenheit (—3°5 C.), never having known 
it lower than 28° (— 2°:2 C.) in former instances, even 
at a depth of 1,000 fathoms; and at other times 
1 Dr. Carpenter’s Preliminary Report on Deep-Sea Dredgings. Pro- 
ceedings of the Royal Society of London, vol. xvii. p. 186. 
