114 REV. JAMES FARQUHARSON ON THE AURORA BOREALIS. 



comparatively, with the other clouds, very dark below, waved or furrowed from 

 north to south, and cut off at its east side in an apparently straight edge, 

 trending nearly north and south. It was coming on very slowly towards the 

 east, and had before next morning prevailed over the other clouds, covering 

 the heavens, and accompanied with a fresh westerly breeze, after a frosty night 

 which the 22nd of November was. This large sheet of cloud was much more 

 elevated than the small detached ones, as was fully proved by some of the 

 latter being projected, in perspective, on its dark under surface, and there ap- 

 pearing as white masses fully enlightened by the moon. 



Now the two arches of aurora of that evening were abruptly terminated at 

 the points where they appeared over the eastern edge of the large cloud ; and 

 the abrupt terminations increased their azimuth distances from the north, as 

 the arches came southwards, still appearing, in their new positions, over the 

 east edge of the cloud. The lower extremities of the streamers, which were as 

 long at these terminations as at any other parts of the arches, appeared even 

 in contact with the cloud ; and I sometimes conceived that they stretched 

 before its eastern edge : but that part being considerably illuminated by the 

 moon, prevented me from being quite positive. Independently, however, of 

 this uncertainty, the appearances are surely decisive of the fact, that the 

 aurora did not extend into the region occupied by the western cloud ; and 

 being seen over it at an angle not much higher than its own, occupied there- 

 fore a region of nearly equal elevation above the surface of the earth. 



The conclusions to be drawn from these observations harmonize sufficiently 

 with an observation of Capt. Parry and Lieuts. Sherer and Ross, who, at Port- 

 Bowen on the 27th of January, 1825, simultaneously saw " a bright ray of the 

 aurora shoot suddenly downward from the general mass of light, and between 

 them and the land, which was then distant only three thousand yards." (Joum. 

 of a Third Voyage under the orders of Capt. William Parry, R.N. F.R.S. 1826.) 

 The conclusions are, that the region occupied by the aurora borealis is im- 

 mediately above, and contiguous to, the region in which aqueous vapour is 

 forming, or about to be formed, in the shape of clouds. The real height will 

 of course vary with the different states of the atmosphere ; I should not have 

 estimated the height of the phosphorescent clouds, above described, at so much 

 as two thousand feet above the surface, or twice the height of some of the 



