42S On the Aurora Boreaiis. [Dec. 



seen all over France on the 2d of September, O. S. 1621, and he 

 describes it 1))' the name of Aurora Lurealis ; being, a.- far as I 

 know, the first who applied that name, new so well known, and 

 generally received. 



2. From that period till the year 7^7 there is no mention of any 

 Aurora Boreaiis having been seen either in Britain or on the Conti- 

 nent, though the number of observe S during a considerable part of 

 that period was very considerable, and the motives for publication, 

 in consequence of the establishment ot the Royal Society, and 

 x'arious similar institutions in different parts of Europe, were greatly 

 increased. Hence there is every reason to believe that the Aurora 

 Boreaiis was very uncommon during almost the whole of the seven- 

 teenth century. On November the 10th, 1 7^7* ar » Aurora was 

 seen in Ireland by Mr. Neve, and is described as such in the Philo- 

 sophical Transactions. During the same year Olaus Romer observed 

 the same appearance thr^e several times at Copenhagen. The 

 bishop of Hereford observed another in the night between the 9th 

 and 10th of August, IJOS, and communicated an account of it to 

 the Royal Society. At last, on the 6th of March, 1716, a very 

 splendid one was seen bv Dr. Ualley at London. He observed it 

 with great attention, and has published a very minute description of 

 it, together with an hypothetic explanation, in the Philosophical 

 Transactions for 1716, vol. xxix. p. 406. 



Since that period they were seen very frequently both in Britain 

 and in every other part of Europe ; and innumerable descriptions of 

 them have been published. Indeed no phenomenon has been more 

 fomih'ar to meteorologists; and hence probably the reason why, like 

 some other very common appearances, (the fall of hail, for example,) 

 so very little progress has been marie in explaining it. It was very 

 common about the year 179— > and continued so for several years 

 afterwards ; but for some years past it has become rare again. 

 Hence it is very likely that during the nineteenth century it may 

 he as uncommon a phenomenon as it was during the seventeenth. 



3. The appearance of the Aurora Boreaiis is so familiar to most 

 persons at present that a minute description of it scarcely seems 

 necessary. It consists of beams of a very pale light always situated 

 in the northern part of the sky, and seemingly verging towards a 

 point situated not very far from the vertex. These beams are con- 

 stantly shifting their places by sudden flashes, so that the whole 

 appear as if they were in motion. Hence the name streamers and 

 merry dancers, by which they are distinguished in different parts of 

 Scotland. Other appearances are frequently to be seen besides the 

 beams, but these are constant, and I conceive them to constitute 

 ihe essential part of the phenomenon. 



4. The Aurora Boreaiis is observed in every kind of weather, and 

 in every season of the year; though winter being the season most 

 favourable for seeing then 1 , we may suppose that a greater number 

 have been observed during that : it of the year than during summer, 

 when the shortness oi the night renders it particularly difficult to 



