~2oi Mr Laidlaw's account of the Aurora Borcalis, Sj-c. 



vens that directed my attention to the E., T am uncertain; but I 

 first observed that in the eastern part the separated portions or 

 nebula? had assumed a striated or rather crinited appearance, the 

 lines of each individual nebula pointing S. E., even while they 

 moved all westward, following one another in an order parallel 

 as to each other, but obliquely as to their position on the arch, 

 so that to a careless observer the first general form of the arch 

 would have seemed to be preserved : — only that at, and on a 

 little on each side of the meridian, the general continuous line 

 of the arch was interrupted ; and here an interesting change 

 took place in the direction of the striae of the nebulas, or ra- 

 ther in the order in which they appeared when farther east : — 

 For, on crossing the meridian, they veered to the right, and form- 

 ed on the western part of the arch, with the striated appearance 

 pointing S. W. During the time that this movement continued, 

 coruscations were apparent, and sudden alternate disappearances 

 and reappearances of the brightness, similar to what is often 

 observed in the common streamers ; the striated divisions not 

 being always, nor throughout the whole length of the arch, 

 distinctly separated from each other. These coruscations were 

 most apparent in the eastern quarter, although they sometimes 

 flashed from one end of the arch to the other, and always from 

 east to west. 



The motions of the striated divisions had the apparent ve- 

 locity of clouds in a gale of wind, but the shifting and flashing 

 was simiiar to that of the streamers usually seen in the north. 

 I have since learned from two different persons, one in this 

 neighbourhood and the other in Liddesdale, that there were 

 two arches that evening, one a little after sunset, which was 

 not so bright and soon disappeared ; and that the second flash- 

 ed out at once bright into the sky. 



It has since occurred to me that the motion of the striated 

 portions of the arch from E. to W., and which seemed so sin- 

 gular, would be best described by referring it to the motion of 

 a wheel with radiated teeth. The motion of such seen in per- 

 spective, would exactly represent the extraordinary appearance 

 attempted to be described. 



