176 Aurora Borealis. 



Those species to which an asterisk is prefixed are new. I have 

 been surprised at the great number of these, and others may suppose 

 me deceived. But I apprehend that I have fallen short of the num- 

 ber of distinct species, rather than exceeded it. Numerous speci- 

 mens of most of these species are in my collection, which I shall ever 

 be happy to exhibit; and for a reasonable return, I am ready to fur- 

 nish plaster casts and moulds of my best specimens, colored like the 

 rock, with a few of the specimens in the rocks. 



1 have given the above summary, chiefly because I have had fre- 

 quent enquiries on the subject from scientific gendemen, and because 

 it may be a long time before I shall be prepared to give an account 

 in detail. 



3. Ohservations on the Aurora Borealis of January ^bth, 1837; by 

 Denison Olmsted, Professor of Natural Philosophy and Astron- 

 omy in Yale College. 



The 17th of November, 1835, the 22d of April, 1836, and the 

 25th of January, 1837, have severally been rendered memorable for 

 the occurrence of the Aurora Borealis, in forms and colors more 

 magnificent and splendid, than any others witnessed by the present 

 generation. The first of these has been already noticed in this 

 Journal. (See vol. xxix. p. 388.) It was distinguished for exhib- 

 iting, on a grand scale, nearly all the varieties of the anrora ever 

 observed in our climate, including the bank of auroral vapor in the 

 North — the streamers — the arches — the corona formed around the 

 magnetic pole of the Dipping Needle — and the undulations or Merry 

 Dancers ; while the whole were set off by that peculiar display of 

 crimson light, which usually attends the most remarkable displays of 

 the aurora. The second, that of April 22d, was distinguished above 

 all others which I have witnessed for the auroral waves. They be- 

 gan to be observed before the end of twilight, and continued nearly 

 all night, following each other with astonishing celerity. My friend 

 Mr. Twining and myself, formed each a separate judgment of the 

 velocity, and agreed in the opinion that die time occupied by a wave 

 in ascending through 45 degrees, was about half a second, — a swifter 

 motion than either had ever observed in nature before. The display 

 of these undulations from half past 11, and onward, was striking 

 beyond conception. Their course was generally upward towards the 

 pole of the dipping needle. The evening of the 8th of May, also, 



