52 RECORD OF AURORAL PHENOMENA. 



The middle portions of some of these arches ran horizontally across the sky, whilst their extremi- 

 ties, making sudden curves, arrived at the common origin and termination of all the arches, 

 which were seated for the greater part of the night. about 4° above each horizon. At one time, 

 the light was arranged in a series of curves, including each other and having their convexities 

 turned towards the north on both sides of the zenith. In short, their arrangement was con- 

 tinually varying, but the breadth of the arches at all times was greater in the zenith. Large 

 and diffuse columns of light sometimes shot up at right angles from the convex side of the 

 arches, and portions of broken arches were occasionally seen in various parts of the sky, lying 

 obliquely across the general line of direction. The changes of form were not produced by a ■ 

 quick flashing motion, but by the different parts of a new arch appearing simultaneously but 

 faintly, then gradually brightening up in a manner that could be traced only by keeping the eye 

 steadfastly fixed on a clear part of the sky and watching the evolution of the light there. 



At midnight, a clear blue sky surrounded the zenith to the distance of about 20°. The rest of 

 the sky had a light-grayish appearance, resembling the light of the milky way ; many stars 

 shining brightly at the time. In some spots this diffused light brightened up for a moment or 

 two, assuming at the same time a yellowish hue. 



At 12h. 30m., there was an arch in the south about 15° high, and various irregular masses of 

 light in the north, the rest of the sky being of a deep blue. 



At 2h., the sky very clear. At this time the Aurora was very brilliant, and its motions so rapid 

 that it was impossible to record them in the order of their occurrence with anything like 

 accuracy. 



At one period, the S. W. part of the sky was occupied by a mass of dense light, which was con- 

 nected with a similar mass in the east by a current of light about 4° broad, moving with extreme 

 velocity from W. to E. This stream of light bore a stronger resemblance to a cascade of 

 water than to anything else I can liken it to ; and it in general flowed from the one mass of light 

 to the other, but sometimes its eastern extremity curled back in various directions, forming, as 

 it were, beautiful eddies. The dark lines or spaces, whose instantaneous appearance and dis- 

 appearance evinced the motion of the light, lay perpendicular to its line of direction, or pointing 

 to the north and south. 



For an instant, when the motions were most rapid, the light became very vivid, and assumed a 

 reddish hue. At this moment, a loud crash was heard, similar to what is produced by a large 

 piece of ice floating down a river and crushing against a stone. 



This noise was not repeated, and, as it appeared to come from the river, would not have been 

 noticed unless for its contemporaneous occurrence with the brightening of the Aurora. The 

 air at this time was rather favorable for the transmission of sound, the Rapid being distinctly 

 heard."— Ibid., p. G23. 



December 30, 1820. Temp. —48°. 



"At 5h. p. m., an arch-formed Aurora extended completely across the sky from the N. W. by N. 

 to the S. E. by E. From the N. W. end of this arch, a pencil of light rose perpendicularly, and 

 terminated at the zenith. Its hue and brightness were equal to that of the milky way, which 

 was distinctly visible at the time. 



At 8h. p. m., two columns of light rose perpendicularly from the horizon, in the N. W. and S. E., 

 to the height of 10°. Their summits being connected by a nearly horizontal beam of light, a 

 depressed arch was formed to the northward of the zenith, from various parts of which pencils of 

 light shot up directly towards the south, and rising 40° or 50°. Portions of two smaller and 

 concentric arches were occasionally seen under the other. 



At 9h. the Aurora continued to exhibit modifications of the appearances above described. 



At midnight, an irregular mass of light, having a spirally-twisted form, rose in the horizon in the 

 iV. W. by JV. to the height of 60°, apparently perpendicularly, then, turning to the northward, 

 it continued its course horizontally across the sky ; and, lastly, bent suddenly and obliquely to 

 terminate in the S. E. horizon." — Ibid., p. 625. 



