72 Particulars respecting an irised Aurora Borealis. 



Art. 'KTV .—Particulais respecting an irised Aurora Borealis, com- 

 municated by James Bowdoin, Esq. 



TO PROFESSOR SILLIMAW. 



Boston, Nov. IG, 1829. 



Dear Sir — On Saturday evening, Sept. 8, 1827, being at Augus- 

 ta in Maine, I called the attention of Doct. E. S. Tappan, about 

 half past 9 o'clock, to a bright and well defined arch, extending to- 

 wards the East and West, whose crown was about 45° above the 

 northern horizon. It almost instantly disappeared. How near the 

 horizon, or how long the arch was visible, I had not an opportunity of 

 knowing. It was even brighter, than that I had witnessed at Boston 

 a fortnight before. 



My friend and fellow traveller, G. Ralston, Esq. of Philadelphia, 

 with Dr. Tappan and myself then saw pencils, or rather columns 

 perfectly irised ; very strongly resembling regular segments of a fine 

 rainbow, in the disposition and arrangement of colors and in shape ; 

 although, in some other particulars, having the appearance of clouds, 

 so illuminated. Each of these pencils, or columns, the sides of which 

 were parallel, and their ends regularly and smoothly truncated per- 

 pendicularly to these sides, was somewhere about half a degree in 

 width ; and in length about eight degrees, though varying in both par- 

 ticulars. They were not 7'adii from the north, but parallel to each 

 other, running from a little East of North : their lower extremities 

 being about 20° from the horizon. , You will of course note here, 

 that the bearing of these columns differed much from that of the arch 

 before mentioned. From parallels, these soon became " merry dan- 

 cers," as they are elsewhere called, and bent rapidly, and continued 

 nimbly playing into curves of small circles ; some times looking as 

 if gracefully folded and twisted, like the most delicate gauze. 



Of the disposition of the colors, whether in precisely the same or- 

 der with those of the solar bow (if indeed any other could be form- 

 ed,) my notes do not inform me ; and taking for granted that though 

 new to me, others had often seen the same thing, my memory does 

 not furnish me with the side or edge, (whether towards the West or 

 East,) on which was the red tint; nor whether it was upon the same 

 side of each of the columns. These appear to me important facts, 

 and I greatly regret that they were not noted when fresh in my re- 

 collection. 



