102 RECORD OF AURORAL PHENOMENA. 



sensibly dimmed by the most vivid of the coruscations, which appeared, in this respect, not to 

 differ from any thin vapor or cloud floating in the atmosphere. The gold leaf of the electrometer, 

 as well as the magnetic needle suspended in the Observatory, was carefully attended to, but 

 neither of them suffered any sensible disturbance." — Ibid., pp. 141-42. 



N. B — 1. At noon, a thin fleecy cloud. 



2. Commenced in N. TV., and ran more faintly to N. by W. 



February 10, 1820. 



"At a quarter past six p. m. on that day, the Aurora began to appear in the south and S. W,, in 

 detached and not very brilliant pencils of rays darting upwards from near the horizon. 



Soon after, an arch of the usual broken and irregular kind appeared in the western quarter of the 

 heavens, extending from N. W. to south, and being from 5° to 8° high in the centre. From the 

 upper part of the arch proceeded a few faint coruscations reaching to no great height. 



At a quarter before seven, a second and better-defined arch crossed over from S. E. to N. W. byN., 

 passing on the northern side of the zenith, from which it was distant from 10° to 15° in the 

 centre. 



This arch was very narrow, and seemed to be formed of two parts, each shooting with great rapidity 

 from those parts where the legs stood, and joining in the centre. In a short time, this second 

 arch entirely disappeared, and the first became less brilliant. 



The phenomenon was then for some minutes confined to some bright pencils of rays in the south 

 and S. S. E., which were generally parallel to each other, but sometimes also diverged at an 

 angle of about 15°. 



At a quarter past seven, two long and narrow streams of light crossed over, at 35° to 40° of alti- 

 tude, on the western side of the zenith, from the N. W. by N. and south points of the horizon. 

 Their upper ends did not quite meet in the centre so as to complete an arch, but inclined to the 

 shape of shepherds' crooks, as described on the 15th of January, and often remarked by former 

 observers ; but they were neither so brilliant nor so well defined as when we saw them before. 



About a quarter before eight, as we were returning on board from the Observatory, the low arch 

 to the westward first described, and which had never altogether disappeared, increased con- 

 siderably in brilliancy. It was still, however, so irregular as to appear in detached roundish 

 clouds or blotches, from which the pencils, which shot upwards, appeared immediately to pro- 

 ceed. These pencils, which were infinitely varied both in length and breadth, were observed to 

 have also a slow, though very sensible, lateral motion from north to south and vice versa; and we 

 remarked on one occasion that, when two of them met and had the appearance of overlapping, 

 they produced, for about fifteen seconds, the most intense degree of light we had yet seen from 

 the Aurora. Tlie 2^ncils appeared generally to travel bodily in one direction, but sometimes to 

 widen out in both at the same time. 



We were all decidedly of opinion that the fixed stars were very perceptibly dimmed by this pheno- 

 menon, which gradually disappeared by nine o'clock." — Ibid., p. 142. 



N. B — 1. At p. in., a very brilliant display S. and S. W. 



2. Soon after, an arch from N. W. to S. 



3. At a quarter before seven, a second arch, better defined, from S. E. to N. TV. by N. 



4. Then for some minutes coufmed to some pencils of rays in S. and S. E. 



5. At Th. 15m., two long streams of light, west side of zenith, from N. W. by N. and S. 



points of the horizon. 

 G. Lateral motion from north to south. 

 1. The pencils appeared to travel bodily in one direction. 



8. Disappeared at 9h. p. in. 



9. Fixed stars perceptibly dimmed. 



February 11, 1820. 



"At half-past eight p. m., the Aurora Borealis made its appearance for a short time in an arch, 

 very irregular but at times very bright, from S. W. to S. S. E., at 4° or 5° above the horizon 

 in the centre." — Ibid., p. 1 14. 



