RECORD OF AURORAL PHENOMENA. 39 



The altitudes and dimensions of the different masses of light were ascertained merely by the eye, 

 and, therefore, have no pretensions to accuracy ; and it is only the apparent shapes that are 

 described, the effect of perspective not being taken into account. 

 The bearings given of the Aurora are also to be taken with some latitude, but they are more likely 

 to be generally correct than the altitudes, as they were ascertained by the different angles of our 

 buildings ; or, in some cases, when the masses of light were near the horizon, by their relations 

 to distant trees and peaks of hills, whose bearings from the spot of observation were known. 

 To reduce the bearings given to magnetic bearings, the easterly mean variation of the compass at 



Fort Enterprise, amounting to 36° 20', is to be applied. 

 The dip of the needle there was 86° 59'. 



To show the condition of the atmosphere with regard to the transmission of sound, and its capacity 

 for moisture, the state of a rapid about a quarter of a mile from the house, which continued 

 open all the winter, has been occasionally mentioned. 

 The forms of the Aurora are described in such language as occurred at the time, without any regard 

 whatever to theory; but it maybe proper to remark that, in reference to Mr. Dalton's opinions, 

 detailed in Bees'* Cyclopedia (which comprised the whole of my limited reading upon the subject 

 up to the time of observation), I have been more particular in noting the directions of the small 

 slender beams of light of which the masses were sometimes composed, than I should otherwise 

 have thought necessary. 

 It will be seen that the following observations do not accord with the positions he lays down ; that, 

 contrary to his statement, the beams would not always meet in a point if prolonged upwards; 

 that they do not always converge to the place in the heavens to which the south pole of the 

 dipping needle points; and that the rainbow-like arches do not invariably cross the magnetic 

 meridian at right angles. 

 But, independent of all theory, I think the following notes will at least serve to prove that the 

 Aurora is occasionally seated in a region of the air below a species of cloud which is knoivn to 

 possess no great altitude. I allude to that modification of cirro-stratus which, descending low in 

 the atmosphere, produces a hazy contiuuity of cloud over head, or fog bank in the hor.zon. 

 Indeed, I am inclined to infer that the Aurora Borcalis is constantly accompanied by, or imme- 

 diately 'precedes, the formation of one or other of the various forms of cirro-stratus. 

 On the 13th of November and 18th of December, its connection with a cloud intermediate between 

 cirrus and cirro-stratus is mentioned ; but the most vivid coruscations of the Aurora were 

 observed when there were only a few thin attenuated shoots of cirro-stratus floating in the air, 

 or when that cloud was so rare that its existence was only known by the production of a halo 



round the moon. 

 The bright moonlight of December was peculiarly favorable for observations of this kind. Had 

 the nights be'en dark, many of the attenuated streaks of cloud hereafter mentioned would have 



been totally invisible. . 



The'natives of this country pretend to foretell wind by the rapidity of the motions of the Aurora, 

 and say that when it spreads over the sky in an uniform sheet of light, it ,s followed by fine 

 weather and that the changes thus indicated are more or less speedy, according to the appear- 

 ance of the meteor early or late in the evening. Our observations were not continued long 

 enough to confirm or contradict these notions; but it may be perhaps worthy of notice that 

 certain kinds of cirro-stratus are also regarded by meteorologists as sure iudicat.ons of wind 



and rain. , ,, ,. 



In reference to Mr. Dalton's opinion that the arches of the Aurora always cross the magnetic 

 meridian at right angles, it may be observed that there is very often an apparent convergence of 

 the parts of the Aurora towards the magnetic east and west, or to some point in their neigh- 

 borhood; but the light in its passage across the sky, even when it traversed the zenith, very 

 seldom appeared to the eye to describe the segment of a circle, but was either elliptical or tormed 

 various irregular curves and flexures. „,,■,, 



I think I have on some occasions discerned a polarity in the masses of cloud belonging to a 

 certain kind of cirro-stratus which approaches to cirrus, by which their long diameters, having 



