An Account of an Aurora Borealis observed at Glasgow. 4/ 



that in the metropolis the whole is considered as an imposition, 

 and passed over in consequence as miworthy of notice. But 

 surely as long as a possibility exists of its not being a fraud; no 

 investigation which science can afford ought to be omitted in a 

 case which, if true, will throw an important light upon some 

 phaenomena which in our present state of knowledge are de- 

 servedly ranked amongst the most interesting and curious in the 

 oeconomy of nature. 



Your obedient servant, 



E. S. 



X. Account by M. Cliev. Dupin, Corresponding Member of the 

 French Institute, ^c. of an Aurora Borealis observed at Glas- 

 goiv the 1 9th of September, contained in a Letter to M. Arago. 

 Communicated to the Academy of Sciences of the Institute of 

 France, the 29th oj Sept. 1817. 

 -^ Glasgow, Sept. 20, 1817. 



JL ESTERDAY, the 19th of September, a little before nine o'clock 

 at night, I went to visit the Observatory of Glasgow, which is 

 built on the summit of a hill to the north-west of the city. I was 

 accompanied by Dr. Ure, a gentleman of scientific celebrity, who 

 has principally contributed by his zeal and his cares to the for- 

 mation of a Society, whose voluntary subscriptions have defrayed 

 the whole expense of erecting the edifice and purchasing the in- 

 struments, which are numerous and very excellent. 



The night was fine, the moon and the stars were of a sparkling 

 brilliancy. When we arrived at the Observatory the heavens 

 towards the north exhibited some whitish shootings, which be- 

 coming less and less uncertain, soon displayed the appearance of 

 an aurora borealis. We then ascended to the terrace above 

 the Observatory, in order to embrace at one view all the luminous 

 parts. In enjoying for the first time this imposing spectacle, I 

 experienced an astonishment and pleasure which I cannot ex- 

 press to yon ; nor can I sufficiently prize my good fortune in see- 

 ing one of the most beautiful pha?nomena of which this country 

 can boast. 



The light of the aurora borealis extended from the north in a 

 space terminated by a vertical circle, the plane of which was 

 nearly perpendicular to the direction of the magnetic needle. 

 The zenith was the part least luminous — it seemed a centre from 

 which the streamers emanated, and ^vhich as they developed 

 themselves became more and mor^ brilliant in proportion as 

 they approached the horizon. However, they never descended 

 that length, but terminated irregularly at fifteen or twenty de- 

 grees above it, presenting an angulous contour like those glories 

 with which painters environ the throne of the divinity. 



The 



