630 PHILOSOPHICAL TRANSACTIONS. [aNNO 17Q0. 



those observed by Mr. Cavallo, in London ; by Mr. Swinton, at Oxford ; by 

 Dr. Huxham, at Plymouth ; and by Mr. Sparshal, at Wells, in Norfolk ; Mr. 

 H. cannot entertain a doubt, that these arches had all the same origin ; and that 

 they ought to be considered as a species of that kind of meteor called aurora 

 borealis. 



IF. Extract of a Letter from the Rev, F, J. H. fVollaston, M. A., F. R. S. 

 (dated Sydney College, Cambridge, February 14, \784,J to the Rev. Francis 

 JVollaston, LL.B., F.R.S., containing the Observation of a Luminous Arch. 

 p. 43. 



I send you an account of a remarkable stream of light which appeared last 

 night, from about g^ 5"™ to 9** 25*", extending entirely across the hemisphere 

 from w. to E. It rose from the horizon, about 10° s. of w., near (J and y Ceti; 

 thence ascended in a straight line, inclining a little s. to $ and e Tauri, where it 

 made an angle with its former course, and proceeded nearly in a vertical circle 

 over j3 Aurigae, ^ Ursse Majoris, by Cor Caroli to Arcturus, setting in the hori- 

 zon about 20° N. of E. The light was steady, not undulating like Aurora ; and 

 as it converged towards the horizon at each end, had much the appearance 

 which I conceive the tail of a comet must make whose nucleus is just in the 

 horizon. That was particularly the case at the w. end, where it was brightest, 

 becoming gradually fainter towards the zenith ; the e. part was nearly of the 

 same brightness. The greatest breadth of the stream in the zenith was about 

 equal to the distance between the pointers in Ursa Major. It disappeared gra- 

 dually. When first I saw it, it did not incline so much towards the s. at its w. 

 end as afterwards; but rose directly up from (J^Ceti to the zenith. I remarked 

 this, because I never saw a stream extend so steadily across the heavens. There 

 was very little of Aurora in any other part of the sky ; indeed what would not 

 have been observed at all, had it not been for this stream. 



y. Of a Luminous Arch. By the Rev. Mr. B, Hutchinson, p. 45. 



Last night, (Monday, Feb. 23, 1784,) at Q o'clock, a very uncommon 

 aurora borealis appeared at Kimbolton. When Mr. H. saw it, it had formed a 

 perfect, uniform semi-circle, of the apparent breadth of half a yard, reaching 

 like the rainbow (which it entirely resembled, only that its colour was simple,) 

 from the w. s. w. horizon to that of the e. n. e. Some of the brightest stars of 

 the Bull only just could be seen through it. The whole hemisphere was without 

 a cloud ; the wind had gone down at west ; a slight frost, after a warm thaw, 

 was taking place ; and there was no other aurora borealis in the heavens till this 

 began to fade away, which then however arose a little, due N.^but without any 



