RECORD OF AURORAL PHENOMENA. 53 



December 31, 1820. Temp. —40°. 



"At 6h. 35m. p. m., an arch-formed Aurora 15° high, extremities bearing A. by W. and E. by S. 

 From its north end, several rays rose to the height of 10° or 12°, having a direction to the south. 



At 9h., a zone of light, rising from the horizon in the A". E., swept round the horizon to the east- 

 ward and southward, with a gradual ascent, until it bore S. W. and had an elevation of 35°; 

 from thence it gradually descended, and finally terminated in the N. W. by N. point of the horizon. 



Near the eastern horizon, this zone was coutiuuous, but towards the south it was composed of thin 

 and parallel layers. 



At midnight, the Aurora covered the sky in fleecy masses, having the same apparent convergence 

 to the N. W. and S. E. points that has been described on former occasions." — Ibid., p. 626. 



February 13, 1821. 



"At midnight, several layers of cirro-stratus in the northern half of the sky with clear blue intervals. 



A zone of light existed in the north, its extremities bearing N. W. and E. N. E. It was com- 

 posed of parallel beams pointing to the southward, and having a quick lateral motion. The 

 eastern extremity of the zone was the most brilliant, and it sometimes rolled back upon itself, 

 producing various curtain-like appearances, during which motions it passed in front of the neigh- 

 boring clouds and completely hid them. 



The southern half of the sky was overspread with thin white clouds, through which a few stars 

 appeared. When these clouds passed over the face of the moon, they produced a bur imme- 

 diately around it, and a halo at the distance of 15°. The northern edge of the halo was occa- 

 sionally illuminated with the yellowish-red light of the Aurora, which gradually faded away into 

 the white moonlight reflected from the cloud. 



The zone in a short time broke up, and its parts approached the zenith, often in their course 

 whirling into a circular form with an extremely rapid motion. At those times, the beams of 

 light appeared to be perpendicular to the horizon, and emitted various prismatic rays, of which 

 yellow and pale violet were the most conspicuous. Sometimes the violet merely tipped the 

 beams; at other times it appeared throughout their whole length. When these beams were 

 arranged in the circular form, so as to form a ring, their length varied from 2° to 4°. 



The light appeared this evening, to the eye, to be near the earth, a thin white haze evidently floating 

 behind or above it, in some places near the moon's situation in the sky. 



The needle, by Mr. Franklin's observations, diverged very much to-night. 



A very short time after these observations were made, the whole sky was overspread by a tolerably 

 dense, uniform, hazy white cloud, which hid the stars and considerably obscured the moon. The 

 Aurora shot across this cloud from A. N. W. to S. S. E., in the form of parallel arches which 

 emitted a bright yellowish-white light. 



The arches were of short duration, and when they disappeared their site was observed to be 

 occupied by the unaltered stratum of cloud." — Ibid., p. 627. 



March 8, 1821. 



"At 6h. p. m., before the daylight was gone, the Aurora appeared in the S. E., stretching up 

 towards the zenith. 



At 7h., two faiut arches crossed the zenith. 



Twilight. The Aurora was bright and copious all the evening. 



At lh. a. m. (9th), it was extremely beautiful and brilliant, but its changes were too various and 

 rapid to be described. Its intestine motions were curved, waved, and serpentine. 



Sometimes it appeared in large masses, like the modification of cloud termed the cumulus; at other 

 times it assumed the curtain-like appearance formerly described ; and occasionally it split into 

 beams varying much in altitude, but generally perpendicular to the horizon. 



One of its forms was very remarkable. It was a hollow truncated cone of light, formed of rays 

 originating about 20° about the horizon, on every side, and terminating about 3° or 4° from the 

 zenith. These rays had much lateral motion, and emitted a most brilliant green light, inter- 

 mixed with a bright purple. Their convergence was very regular, and, had they been prolonged, 

 they would have terminated in the zenith. The cone was, in fact, the phenomenon we have 

 termed Corona Borealis, with beams longer than usual." — Ibid., p. 627. 



