4(i RECORD OF AURORAL THE NO MEN A. 



When tliis beam had attained its extreme length, it formed a half-arch concave to the westward. 

 It was scarcely formed, however, before it divided into a number of small parts, which, being 

 segments of circles and rising successively one above the other, formed a kind of tiled arch. It 

 disappeared altogether in three or four minutes, leaving the clouds unaltered in appearance. 



At 12h. 40m., the sky had become clear as far as the zenith. The edge of the clouds, which were 

 now overhead, was still composed of parallel bars directed to the north and south. Under these 

 bars, a few streaks or threads of very rare cloud were seen floating, and at times emitting a 

 faint orange-colored light. The clouds in the southern part of the sky, although they appeared 

 pretty dense in the bright moonlight, were yet rare enough to allow the larger stars to appear 

 through them. 



By one o'clock, the whole mass of cloud had gathered together towards the south, and disappeared 

 in the horizon ; but, at the same time, a few long and very rare threads of cloud, which were at 

 intervals faintly luminous, shot athwart from east to west in the deep blue of the northern part 

 of the sky. On former occasions, the Aurora had been observed to illuminate the face of the 

 clouds next the earth; but the present night was remarkably favorable for the observance of 

 that phenomenon, the brightness of the moonlight, and the clearness of the sky, rendering the 

 clouds very visible and well defined." — Ibid., p. 609. 



December 19, 1820. Temp. —38°. 



"At midnight the sky cleared up, a few cirro-strati were seen to the southward, and there was a 

 slight bur round the moon. The rest of the sky was of a grayish blue color. 

 At this time, a broad bank of the Aurora appeared in the north, lying horizontally, at an elevation 

 of 25°. There were also a few long parallel streamers to the westward, flashing in the direction 

 of their lengths from W. by N. to E. by S. They disappeared suddenly, leaving in their site a 

 faint yellowish light."— Ibid., p. (ill. 



December 20, 1820. Temp. —46.0°. 



"At lOh. 45m., bright moonlight. The sky, which had previously been very clear, was suddenly 

 overspread by a thin stratum of fleecy clouds. They were in general orbicular, but were much 

 crowded, so as to leave only small interstices of clear blue sky. A few stars were visible through 

 the rarer parts. About 1° or 8° above the northern horizon, there existed a mass of cloud 

 rather more dense, which began soon after its formation to emit a faint yellowish light. In two 

 minutes, the light became brighter, and spread towards the S. W. by a slow waving motion, 

 like an increasing volume of smoke rolling parallel to the horizon. It continued sweeping round 

 the sky in this manner until the produced end bore N. W., and then became irregularly elevated 

 in the middle, assuming an arched form. At the instant at which this elevation took place, a 

 stream of light, issuing from the S. W., formed an arch about 2° higher than the other, and 

 parallel to it. The second arch exhibited nearly the colors of the rainbow. 



The red color occupied its under edge, and it darted down towards the inferior areh a number of 

 light-red, fringe-like processes. The two arches were scarcely formed when they disappeared, 

 but instantly appeared again, and continued to do so, in rapid succession, for a minute or two; 

 the upper one retaining its prismatic tints, and the under one an uniform pale-yellow color. 

 The motion of the light by which the arches were reproduced was sometimes from right to left, 

 sometimes in the opposite direction. The upper arch, too, was occasionally split into narrow 

 parallel beams, which had not only a rapid lateral motion in the direction of the arch, but were 

 also lengthened out, both upwards and downwards, by sudden flashes. At such moments, the 

 colored tints were most vivid; the red always predominating. 



About five minutes after the first appearance of the Aurora, a bright mass of light was observed 

 bearing N. N. W., from which a column, possessing prismatic tints, shot up as high as the 

 zenith ; a similar column at the same time springing to meet it from the site of the two arches 

 which had now disappeared. A brilliant arch was thus formed, whose extremities bore W. N. W. 

 and S. S. E. In au instant thereafter, the whole sky was covered with small arcs and irregular 

 masses of light, mostly composed of short parallel beams. These masses moved rapidly from 

 the horizon towards the zenith, and back again. The duration of this phenomenon was about 

 seven or eight minutes, when the light wholly disappeared. 



