VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 45g 



noctial west, a red and very bright column, which ascended to the third part 

 of the heavens, and a little after, it became curved in the shape of the 

 rainbow. 



At half after 8, almost in an instant of time, the bright zone, from the 8th 

 degree west to the 50th east, became more vivid, and rose higher; and above 

 this appeared a new large one, of a red fiery colour, with several successive 

 streamings tending upward, and passing Co degrees of altitude; the western 

 part had assumed the form of a thin cloud. At 12, the light of the aurora 

 was nearly extinct, there appearing only a very weak, light along the tops of the 

 mountains. Twenty minutes after, there appeared a white brightish beam, at 

 30° west, and 60° high; but it soon became invisible. In half an hour after, 

 a very weak light remained in the west, near the horizon; which had not been 

 observable, if the brightness of the preceding phenomenon had not invited to 

 continue the observation. 



3. Observed at the Observatory of the Institute of Bononia. By Dr. Eustachio 

 Zanotti, Deputy Professor of ^4stronomy, p. 5y3. — The aurora borealis, which 

 was formerly a rare phenomenon, and almost unknown in this climate, is now 

 become very frequent. In Bononia a great number have been observed for 

 some years past. This time it was so very remarkable, that no one remembers 

 to have ever seen the like. As to its extent, it spread so as to occupy about 

 140° of the heavens; and, as to its light, it was so vivid, as by it to distinguish 

 houses at a great distance; which seemed of a red colour, which made some 

 people attribute this light to a fire in the neighbourhood. 



It continued at times variously increasing and decreasing. 



About S*', the aurora formed itself into a concave arch towards the horizon. 

 The polar star was near the top of its convexity, and some stars shone bright in 

 the midst of the light; and, among these, J' and y of Ursa major. The con- 

 cave part was terminated by a basis somewhat dark; which separated the red 

 light of the arch from a white and very bright light that remained within it. 

 The arch, which was 15° broad, was of a deeper colour towards the horizon 

 than towards the pole. The western limit, which was interrupted by clouds, 

 was wider and more irregular than the eastern limit. Fig. 2, pi. 10, exhibits 

 the phenomenon conformable to the description now given. 



At 8*" 34', the red light continued s|)reading, and made, as it were, a basis 

 of a weaker redness. At this time the aurora appeared unsettled and curious, 

 as in fig. 2. At its eastern limit, the pyramid continued visible, but of a more 

 intense colour towards the north, and from its middle there shot up vertically 

 a streak of light, between a white and a yellow colour. A very dark narrow 

 cloud crossed the whole phenomenon, and went to terminate in the pyramid. 



3 N 2 



