Aurora Borealis of November 14, 1837. 289 
summit. Such also is that of Professor Joslin, who supposes 
an intimate connection to exist between clouds of certain forms, 
and auroral phenomena, But these seem to find little support in 
mathematical computation, founded on the observation of par- 
ax. 
During the expedition of Capt. Franklin to the polar regions, 
however, in 1820, contemporaneous observations were made on 
three Auroras, by Lieutenant Hood and Dr. Richardson, in latitude 
64° 2/ 24”, from points eighteen leagues distant from each other ; 
and from the parallactic angles obtained by them, an altitude was 
deduced of two or two and a quarter leagues—equal to six or 
seven English miles. It is possible that the height may diminish 
as we approach the poles. 
According to the theory of M. Hansteen, the auroral cloud is 
an iaideiation from the earth, which rises directly upward, but 
becomes luminous only on escaping from the atmosphere, at a 
height of forty five or fifty miles. 
But there have been differences of opinion in regard to the ori- 
gin of the auroral vapor, as to whether it is terrestrial or celestial. 
That it partakes of the motion of the earth, in its diurnal revolu- 
tion, is sufficiently evident. Whether this fact alone will demon- 
strate it to be a terrestrial emanation, may possibly be disputed ; 
butit is certainly an argument in favor of that belief. 
The Aurora has been represented to be attended with rustling 
or crackling noises. In our latitude we have no very good evi- 
dence of the occurrence of these: and, indeed, if the auroral va- 
por be, in truth situated as far above the earth as our computations 
as yet compel us to place it, we know not how such audible evi- 
dences of its action can reasonably be expected. 'The case would 
be somewhat different, if the sounds described were heavy peals 
or explosions, like the reverberations of thunder. These sounds 
are represented as being more remarkable, and of more frequent oc- 
currence in the higher latitudes. This circumstance might result 
from the more violent action of the Aurora, as we approach the 
poles; but it may, also, be in part, a consequence of the greater 
proximity of the phenomenon to the earth’s surface. M. Mairan, 
believing the auroral matter to ascend from the earth, and during 
a coronal Aurora, from the immediate region of the observer, sup- 
poses these sounds to be occasioned by its upward passage through 
the lower regions of the atmosphere. 
— XXXIV.—No. 2. 37 
