OF A NORTH-WEST PASSAGE. 
293 
In attempting to sail to the eastward, we found the ice become more and 1820. 
more close, and a fog with sleet coming on obliged me to make the ships fast 
to a floe of considerable extent, and five or six feet in thickness, being in Frid ' 
latitude, by account, 68° 24' 18", and longitude 63° 32' 42". We had here 
no bottom with six hundred and ten fathoms of line ; the temperature of the 
sea at one hundred and seventy fathoms was 30°|, that of the surface being 
the same, and of the air 31°. 
As the sun was occasionally visible, notwithstanding the fog, a set of ob- 
servations was begun for ascertaining the variation of the magnetic needle 
on board the Hecla ; but these could with difficulty be obtained on ten 
points of the compass, after which the sun became again obscured. The 
thermometer fell to 23° at night, which was lower than we had before 
experienced it in the course of this month, and the fog froze hard upon the 
rigging. 
The fog continued so thick on the I6th, as to oblige us to keep the ships Sat. 16. 
fast to the floe. In the afternoon the deep-sea clamms were sent down to 
the bottom with two thousand and ten fathoms of line, which were fifty-eight 
minutes in running out, during which time no perceptible check could be 
observed, nor even any alteration in the velocity with which the line ran out. 
In hauling it in again, however, which occupied both ships’ companies above 
an hour and a half, we found such a quantity of the line covered with mud 
as to prove that the whole depth of water was only eight hundred and nine 
fathoms, the rest of the line having continued to run out by its own weight, 
after the instrument had struck the ground. I have before had occasion to 
remark that, on this account, it is not easy to ascertain the actual depth of 
the sea in the usual manner, when it exceeds five or six hundred fathoms. 
A self-registering thermometer, which remained at the bottom for two hours 
and three-quarters, indicated a temperature of 27°*, that of the surface being 
31°, and of the air 34°. Some cubes of wood, whose sides measured two 
inches, were also attached to the clamms, in order to try what increase of 
weight each kind would acquire by the pressure of the water at a great 
depth; the result, as ascertained by Mr. Edwards, is shewn in the follow- 
ing table : — 
* The instrument with which this experiment was made had been a good deal used 
for the same purpose, and did not, perhaps, indicate the temperature with very great 
accuracy. 
