OF THE 18TH OF NOVEMBER, 1835. 
33 
Remarks. 
Having at the time no instruments for determining the bearing or altitude of the 
arch, I was obliged to depend upon the positions of some conspicuous stars, which 
were conveniently situated for that purpose. According to these rough data, the 
altitude was 18°; the angle subtended by the span of the arch about 130°; the bear- 
ing of the centre of the arch north-north-west, true, or very nearly magnetic north ; 
and the arch was consequently at right angles to the magnetic meridian. 
The body of light was nearly colourless ; its brightness was similar to that seen 
on the edge of a cloud when the moon is about to rise behind it, with, however, 
this striking difference, that the stars were distinctly seen through the diffused light 
of its upper surface, and those in the tail of the Bear shone clearly in the very body 
of the light on the right hand. 
With regard to the sketches with which I have attempted to illustrate the pre- 
ceding notes, it is necessary to observe, first, that the extent of horizon renders it 
impossible to give in one view any idea of the magnificent scale on which the original 
was depicted, or even to preserve very correctly the relative proportions of height 
and breadth ; and next, that in sketches I. and II. the rapid motion of the bodies of 
vapoury light, and of the flame-like pencils, must be held in mind : the former bore 
an exact resemblance to the faint reflected light darting across the sides of a room 
from a mirror turned sharply in the hand, and the latter to the lambent flames which 
diluted spirit of wine, poured on a flat surface and ignited, will exhibit when half ex- 
tinguished. 
The pencils which appeared in front of the dark cloud, of which there were not 
more than three, were very distinct in their character from the others ; they were of 
a yellower tinge, and extremely narrow throughout their whole height. I have 
stated, that they issued from the dark cloud ; perhaps it would be more correct to say, 
that they pierced through it; for although I did not observe the instant of their ap- 
pearance, being at the moment engrossed by the display on the left, yet, in each, the 
brightness of the base, which was, as it were, the nucleus of its light, seemed to 
warrant this idea. The mere circumstance, however, of their appearance in front of 
the cloud, tends to elucidate a point on which there exists much difference of opinion, 
the height of the aurora in the atmosphere. The dark cloud itself can scarcely be 
supposed to have occupied a very elevated region ; and it is manifest, that, if these 
brilliant pencils had their origin in, or in advance of, the cloud, their bases must have 
been of inferior altitude to its upper portion, and equally so, if they were identical 
with any continuation of the luminous matter of the arch, concealed by the cloud. 
The first appearance of the aurora at nine o’clock, was that of a dark convex cloud, 
cutting off the luminous arch, and concealing a body of light behind, the eye naturally 
referring the light to a more distant region, while the sharp line of division threw 
the cloud forward. Subsequent appearances, however, did not seem to confirm this 
MDCCCXXXVI. F 
