Auroræ: Their Characters and SpectraCapron, J. Rand
History
Auroræ: Their Characters and Spectra
Capron, J. Rand
Auroras
It began about 7 P.M. during a strong gale from the N.W., with single
bright streamers in the N. and N.W., which covered a large space and
rushed about from place to place with amazing velocity, and had a fine
tremulous motion, illuminating the hemisphere as much as the moon does
eight or nine days from change. About 11 o’clock part of the streamers
appeared as if projected south of the zenith and looked like the pillars
of an immense amphitheatre, presenting a most brilliant spectacle and
seeming to be in a lower region of the atmosphere, and to descend and
ascend in the air for several minutes. (This appears to have been the
formation of a corona.) One streamer passed over Orion, but neither
increased nor diminished its splendour.
_Description of Aurora by Dr. Hayes, 6th January, 1861._
[Sidenote: Dr. Hayes’s Aurora, 6th January, 1861.]
‘Recent Polar Voyages’ contains a narrative of the voyage of Dr. Hayes,
who sailed from Boston on the 6th of July, 1860, and wintered at Port
Foulbe. He witnessed a remarkable display of the Aurora Borealis on the
morning of the 6th January, 1861.
[Sidenote: Development of Aurora.]
The darkness was so profound as to be oppressive. Suddenly, from the rear
of the black cloud which obscured the horizon, flashed a bright ray.
Presently an arch of many colours fixed itself across the sky, and the
Aurora gradually developed.
[Sidenote: Rays changed to glow.]
The space within the arch was filled by the black cloud; but its borders
brightened steadily, though the rays discharged from it were exceeding
capricious, now glaring like a vast conflagration, now beaming like the
glow of a summer morn. More and more intense grew the light, until, from
irregular bursts, it matured into an almost uniform sheet of radiance.
Towards the end of the display its character changed. Lurid fires flung
their awful portents across the sky, before which the stars seemed to
recede and grow pale.
[Sidenote: Mixed colours. Colours change. Tongues of white flame formed.]
The colour of the light was chiefly red; but every tint had its turn,
and sometimes two or three were mingled; blue and yellow streamers shot
across the terrible glare, or, starting side by side from the wide
expanse of the radiant arch, melted into each other, and flung a strange
shade of emerald over the illuminated landscape. Again this green subdues
and overcomes the red; then azure and orange blend in rapid flight,
subtle rays of violet pierce through a broad flash of yellow, and the
combined streams issue in innumerable tongues of white flame, which mount
towards the zenith.
The illustration which accompanies this description in the work is
reproduced on Plate II., and forcibly reminds one of the “curtains” of
the Aurora described in the preceding Chapter by Mons. Lottin.
[Illustration: Plate II.]
_Prof. Lemström’s Aurora of 1st September, 1868._
[Sidenote: Prof. Lemström’s Aurora, 1st September, 1868.]
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