Miscellaneous Intelligence. 143 
of the dark segments ying generally below the peters lick or at 
their base. ‘This segment, according to some, is merely an effect of 
contrast ; according t to pretties it is something cionaciade (or real,) but in- 
dependent of the aurora, caused perhaps by the polar fogs; and others 
consider it the siamese source of the auroral light. I next show, 
that the light cannot be an effect = reflection, except “in rare cases, and 
actually exists where it is shes erv 
In the second paragraph I pass the forms and portions of arches, 
their movements, light, and apparent structure. According to Hans- 
teen, an auroral arch isa Juminous Ting situated in the upper regions 
of the atmosphere, sustained in all its parts a the same height, above 
the earth’s surface, and whose axis corresponds nearly with the mag- 
netic axis of the globe. Such a ring ought to appear more or less 
elevated above the horizon according to the position of the observer, 
and it ought to be seen to cut the plane of the magnetic meridian at 
right angles. ‘The hypothesis of ae which is altogether the 
most probable, has been made the basis of our investigations with a ig 
to the orientation, the height, and Yes amplitude of the arches. Tun 
stand by amplitude, the “angolar distance between the east and so 
alee measured on the ‘plane of the horizon and on the north sides of 
the zenith to — ss The amplitude increases quite regularly dur- 
ing this movement of the arc. It does not become one hundred a 
eighty degrees until the arch has passed the zenith to the southern part of 
the sky. 
It also results from our observations, that the curve of the arch i is 
very similar to that oF a small circle of the celestial sphere. This 
ing the horizon, this right line becomes a hy rbolic curve though 
searcely appreciable, and important only in a theoretical point of view, 
from its connection with the theory assume 
From the simultaneous variation of the heights and amplitudes, fener 
stars, 
The third paragraph is devoted to the rays of the aurora boredis. 
The rays (streamers) are columns of Fo pe suspended in the air; they 
undergo rapid movement or changes, and appear to converge towards 
the magento na where they thus form oer is called the corona. 
18 La Reche rche commandée par M. Fabvre, Lieut. 
y fee : debe vie cf sate at Roi i SOUS la directi tion de M. Paul Gaim mard, Pres 
ord.” ce 
ident de la Commission Scientifique du_ .” They include Reports on / 
‘tism, 2 vols. ; Eorenies l vo e ology, Min a = 
Metallurgy, and Chemistry, 2 vols.; any, Physical Ganrasby: Physiology, 
and Medicine, 2 vols.; Zoology, pee ; Runry of Scandinavia and its Lite 
ture, and History of the Voyage, 4 vols. 
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