342 
A WALK. 
iiig or crackling sound, which I noted on the 2d of 
February, was heard this morning in every direction. 
This sound, as the ‘noise accompanying the aurora,’ 
has been attributed by Wrangell and others, ourselves 
among the rest, to changes of atmospheric temperature 
acting upon the crust of the snow. We heard it most 
distinctly between seven and eight A.M., when the 
solar ray should begin to affect the snow. The mer- 
cury stood at —27° at five, rising to — 19° by nine A. M., 
and attaining a maximum of —2° by noonday. But 
this is not to be regarded as indicating the tempera- 
ture of the snow surface. The snow, when horizontal, 
according to all my observations, differs but little in 
temperature from the atmosphere, owing probably to 
its oblique reception of the solar ray ; while the snow- 
coverings of the hummocks and angular floe-tables, 
which receive the rays at right angles, show by re- 
peated trials a marked augmentation. I venture, 
therefore, to refer this peculiar crisphig sound to the 
unequal contraction and dilatation of these unequally 
presenting surfaces, not to a sudden change of atmos- 
pheric temperature acting upon the snow. 
“ To-day we saw a couple of icebergs looking up in 
the far south. 
March 27, Thursday. The sun shone out, but not 
as yesterday. The little cirrous clouds interfere with 
its brightness, and affect very perceptibly its warmth. 
To the eye, however, the day is undimmed. 
“The wind, which we watch closely as the index 
of our ice-changes, our leading variety, came out at 
seven in the evening from the northward ; and with it 
came a rise of black frost-smoke to the south, showing 
that the old ice-opening had gaped again. I had start- 
ed before this at half past five, with old Blinn, my 
