628 APPENDIX. [No. III. 



At Ih. (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, intermixed 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. 



March 1 1th, 1821 . At midnight, a zone of light was observed extending from 

 the E. to the N.W., lying about 20° above the horizon, and emitting a yellowish- 

 grey light. This zone exhibited some intestine motion, but it was faint, and 

 consisted rather of a brightening up and fading away again of the light, than of 

 flashes. At this time sounds were heard at intervals of from 5 to 10 minutes to 

 a few seconds, resembling the noise of a wand waved smartly through the air. 

 The sounds appeared to issue from various parts of the sky, and as they were 

 frequently simultaneous with a brightening of the Aurora, I was at first 

 inclined to regard them as reports of its motions, but Mr. Wentzel stated them 

 to arise from the contracting of the snow upon the sudden increase of cold, 

 and his opinion was further supported by the same sounds being heard next 

 morning. We heard in the evening from 50 to 100 of the reports, and they 

 continued nearly as frequent after the Aurora had almost faded away, as when 

 it was brightest. 



The air was not very favourable for the transmission of sound, as the rapid 

 was scarcely audible. 



End of Dr. Richardson 's Observations on the Aurora, 



