RECORD OF AURORAL PHENOMENA. 71 



For several hours on the same night, this meteor formed a tolerably well-defined arch from E. S. E. 

 to W. N. W., beiug 6° high in the centre, reaching from one horizon to the other, and confined 

 entirely to the southern side of the heavens. 



Early on the morning of the 16th, it was seen for an hour and a quarter much in the same situa- 

 tion, and on the following evening it appeared faintly in almost every part of the heavens." — 

 Ibid., pp. 155-56. 



N. B. — Resemblance in form of Aurora ; this coincidence may possibly serve to throw some light 

 on the nature and peculiarities of the Aurora. 



January 18, 1822. 



"From llh. p. m. till past midnight, on the 18th, it once more appeared very bright from W. to S. E., 

 having at times a very rapid and irregular motion. Whenever the light was most concentrated 

 it was also the brightest, and almost always in that case we observed it to assume an arch-like 

 form in the southern part of the heavens. 



This was particularly the case on the evening of the 19th, when there appeared two concentric 

 though not altogether continuous arches, extending from S. E. by E. to W. S. W., the highest 

 being 8° to 10° above the horizon, but in this respect at times slowly varying. At llh. p. m., 

 after thus remaining, without any very remarkable alteration, for above two hours, it suddenly 

 became extremely variable, shifting its place laterally with a prodigously rapid motion, but still 

 keeping within the general limits above mentioned both in bearing and altitude. In this lateral 

 motion, which was somewhat of the kind I have endeavored to describe on the 14th of December, 

 it seemed, as it were, to roll over from one end of the arch to the other, while at the same time 

 numberless lighter and less brilliant coruscations were emitted from its upper margin. 



Whenever the phenomenon occupied the smallest space in the heavens, the light was invariably the 

 most intense, and often when several sheets of it appeared to unite, in the manner before 

 explained, the lilac tint was quite vivid; in general its color was yellowish. Stars of the second 

 magnitude were almost obscured by it. 



Towards the end of January, this phenomenon appeared frequently in the S. E. and E. S. E., but 

 it was generally faint, and unmarked by any peculiarity requiring further notice. 



The electrometer was frequently applied to the mast-head chain, and the magnetic needle con- 

 stantly watched during all these appearances, but neither of these was on any one occasion sensibly 

 affected."— Ibid., pp. 156-57. 



March, 1822. 



"The appearance of the Aurora Borealis was less frequent during March than in the preceding 

 winter months, in consequence of the increased duration of daylight at this period. Whatever 

 slight variations might exist in these appearances, it still continued a matter of constant remark 

 to us, that the phenomenon almost invariably commenced in the southeastern quarter of the 

 heavens ; and it is perhaps worthy of notice, that the same thing was observed by Crantz in 

 Greenland (whose very words would truly describe what we so frequently noticed during this 

 winter). 



The arch-like form assumed by the Aurora was also one of its almost invariable peculiarities; the 

 legs of the arch being usually situated somewhere between the east and west points of the 

 horizon, and almost always occupying the southern side of the heavens. 



The only instance of this phenomenon during the month of March deserving particular description, 

 occurred on the evening of the 30th, when it made its appearance as usual in the southeastern 

 horizon, from whence it soon diffused itself in a low but tolerably regular arch extending to the 

 W. S. If. Again, at times, it altogether vanished, and then as suddenly reappeared much in the 

 same situation as before. 



We often fancied that this phenomenon exhibited a light of greater actual intensity when the moon 

 was above the horizon than at other times, thongh its appearance was of course less splendid on 

 that account. Whether this was in reality the case or not, we had no means of correctly judging; 

 but some idea of its brightness may be formed from the circumstance of its being very often 

 distinctly visible when the moon was between her quarters and the full. 



