No. III.] 



Dr. RICHARDSON ON THE AURORA. 



625 



its motions so rapid that it was impossible to record them in the order of their 

 occurrence with any thing like accuracy. 



At one period the S.W. part of the sky was occupied by a mass of dense 

 light, which was connected 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 any thing 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 disappearance evinced the motion of the light, lay perpendi- 

 cular 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 cotemporaneous occurrence with the 

 brightening of the Aurora. The air at this time was rather favourable for the 

 transmission of sound, the rapid being distinctly heard. 



December 30th, 1820. 



Hour. Temp. Wind. 



A.M. 9 - 53 N. W. Light. Clear. Much mist over the rapid. Low 



fog in the valleys. 



Noon, — 52 do. do. Low fog increasing. 



3—50 Nearly calm. Hazy in the horizon. Rapid moderately 



loud. 



9 — 48 W. Moderate. Clear, but a bur round the candle. 

 Midnight,— 47.5 W.S.W. do. do. 



At 5h. p.m., an arch-formed Aurora extended completely across the sky 

 from the N.W. b.N. to the S. E.b. 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 



4 L 



