so 0?i ail Aurora Bor calls 



Art. XL Some Observations on a very interesting Aurora Boreah's, 

 witnessed at Hull on the Evening and Night oj^ October 12. 183S- 

 By George H. Fielding, Esq. M.R.C.S.L., Member of the 

 British Association for the Advancement of Science, Treasurer 

 and Hon. Curator of Comparative Anatomy to the Hull Literary 

 and Philosophical Society, &c. &c. 



On the evening of Saturday, Oct. 12. 1833, we had the 

 most brilliant exhibition of the aurora borealis I have ever 

 seen. The evening was remarkably bright and clear; the 

 sky presented a deep blue tint, and the stars were uncom- 

 monly brilliant; the air felt sharp, the temperature being 

 about 40°; the pressure of the atmosphere 29*832; the wind 

 rather brisk, and from the north-west. At half past 8 p.m. 

 there was a broad, irregular, semicircular belt of vivid white 

 light, stretching across the northern hemisphere of the heavens. 

 The span of the arch was from 70° to 80°, its upper edge 

 reaching as far as the star Eta in Ursa Major, about 18° 

 above the horizon ; and the breadth of the belt, which varied, 

 I should state to be about 5°. It was exactly similar to a 

 rainbow in shape, but of pure white light. 



Below the bow 1 at first thought there was a dark black 

 cloud ; but, on minuter investigation, I found this to be a 

 deception, caused by the extreme brilliancy of the aurora, 

 which threw the surrounding medium into shade, and ob- 

 scured the lustre of the fixed stars so much as to make them 

 seem blue. By degrees the arch extended itself towards the 

 zenith, and included the whole constellation of Ursa Major : 

 it also gradually filled up the concavity down to the horizon, 

 until it finally presented the magnificent appearance of an arc 

 of an immense globe of fire. 



During the whole time of my observation, brilliant radii 

 were shooting up towards the zenith from the convexity of the 

 arch, sometimes broad, sometimes narrow, sometimes vanish- 

 ing immediately, and at others remaining visible for a minute 

 or more, to an altitude of 60° or 70°, and seeming like pillars 

 of flame. The radii mostly disappeared at or before they had 

 attained, an altitude of 90°, but might occasionally be traced 

 in very narrow wavy streaks into the southern hemisphere. 



The most extraordinary appearance, however, was a rapid 

 undulatory motion, accompanied with frequent brisk flashes *, 



* These flashes resembled, both in duration and colour, the silent light- 

 ning frequently seen in the horizon on warm summer evenings, apparently 

 at an immense distance, and when not a cloud is visible. 



I cannot but consider the aurora as an electrical phenomenon, and think 

 that, were it not at such a remote distance, we should have explosions 

 audible as in a thunder storm. This, however, is mere conjecture; but I 



