154 
LAST VOYAGE OF CAPT, ROSS. 
behind a cloud, and the oscillations appear only to take place, 
when beams or fringes of the meteor are on the same plane with 
the dip of the needle. Capt. Franklin was led to consider that 
the effect of the aurora on the needle, varied with its height 
above the earth. That it did not depend on the brilliancy of 
the meteor was manifest, from the fact that in hazy cloudy nights 
the needle deviated considerably, though no aurora was then 
visible, and he felt unable to determine whether this proceeded 
from a concealed aurora behind the clouds, or entirely from the 
state of the atmosphere. Clouds sometimes during the day 
assumed the forms of the aurora, and he was inclined to connect 
with their appearance the deviation of the needle, which was 
occasionally observed at such times. 
The appearance of the aurora is said to be sometimes attended 
with singular noises. Though Parry, Franklin, Richardson, 
Scoresby, Ross and others never heard such noises, and Hood 
and Brook only think they did; all express an opinion to defer 
to the uniform testimony of natives and residents, so far as to 
admit that such sounds may sometimes be audible, but their rare 
occurrence is demonstrated by the fact, that Captain Franklin’s 
party felt unable to confirm this report, though the appearance of 
the aurora had been registered 343 times at Bear Lake, in the 
seasons of 1825 and 1826. The noise as described appears to be 
a sort of crackling, whizzing, rustling sound, compared to that 
of an electric spark—to the falling of hail—to the rustling of a 
large flag in a gale of wind—to the noise made by a flock of 
sheep in breaking through a hedge—to that caused by shaking 
or waving a piece of paper, and to the rushing of wind. Pro¬ 
fessor Jamieson declares his belief in the existence of such sounds, 
and states that he has himself heard them. 
In the polar regions the aurora begins to appear in October, and 
\ aontinues to May, but the lights are the most intensely luminous 
from November to March; it is very various in its duration, it some¬ 
times appears and disappears in the course of a few minutes, at 
other times it lasts during all the night, and occasionally con¬ 
tinues for two or three days together. 
It was now determined to commence the dismantling of the 
