Notice of the Rarer Atmospherical Phenomena in 1824. 55 



torrents of rain that seem to have accompanied the contempo- 

 raneous storm. 



On the morning of the 9th, a pretty brilliant display of the 

 Aurora Borealis was seen for some time. 



The months of October, November, and December, may 

 be said to have had very nearly the same meteorological cha- 

 racter, being very stormy, with very variable temperature and 

 pressure, and an excess of humidity. The pressure during 

 the whole three months scarcely ever exceeded the usual mean. 

 In such a state of the atmosphere, rare and interesting phe- 

 nomena were certainly to be expected ; and, accordingly, they 

 did occur in no small number. The first which may claim 

 our attention is a very curious one, and has frequently at- 

 tracted the notice of philosophers, ever since the phenomena 

 of the rainbow were thought worthy of investigation ; namely, 

 the appearance of what are called Supernumerary Rainbows. 



These were seen on the second of October, about 5 P. M., 

 during a light shower of rain, within the southern limb of a 

 primary one of great brilliancy. There were three additional 

 sets of colours seen close to one another, all having the red 

 outermost. The red, yellow, green, and blue tints could be 

 distinctly observed ; and they varied in brilliancy and breadth 

 as the cloud moved on. 



Dr Langwith was the first who described these supernume- 

 rary bows, (Phil. Trans. 1723 ;) but he saw only " dark- 

 green, light-green, and purple," repeated thrice within the 

 primary bow. M. Bouguer in Peru, saw one entire repetition 

 of the prismatic tints within the primary, frequently ; rarely 

 two repetitions. M. Gentil, in 1756, in France, saw two re- 

 petitions within the primary of the blue tint.; — and M. Dic- 

 quemarre observed supernumeraries outside of the secondary. 

 Similar phenomena were observed by Monge, and Daval. " On 

 the 29th July 1813, Dr Brewster observed these supernume- 

 raries under favourable circumstances, when four repetitions 

 of the red and green bows were seen without the primary vio- 

 let." (Optics, Edin, Encyclop.) September 7th 1819, Mr 

 Macome at Paisley, saw " the lower half of the primary, com- 

 mencing with the green tint, distinctly repeated in the regular 



