104 
REV. JAMES FARQUHARSON ON THE AURORA BOREALIS. 
Trans. 1828, “ On the Height of the Aurora Borealis above the Surface of the 
Earth ; particularly of one seen on the 29th of March, 1 826.” Mr. Dalton in 
that paper, supposing the same luminous belt was seen on the 29th of March at 
places distant from each other at the same time, infers its height to have been 
100 miles and upwards. 
If I shall have occasion to differ widely from Mr. Dalton’s conclusions, I 
beg to do so in terms of high respect for that distinguished individual, whose 
labours have so much benefited science ; and whose opinions I should not have 
ventured to controvert, had I not possessed peculiar advantages for observa- 
tion ; and had I not made on one occasion an observation which appears 
decisive of the question of height, as .will be afterwards stated. 
I do not mean to confine myself, however, to the discussion of that question 
only, but to communicate several very curious results of the numerous obser- 
vations I have made, which as far as I am able to ascertain are not yet gene- 
rally understood among men of science. 
I had announced these results in a short paper published in the Edin. 
Phil. Journ. vol. viii. p. 303, April 1823; they are, “That the aurora bo- 
realis has in all cases a determinate arrangement and figure, and follows an 
invariable order in its appearance and progress ; — that the streamers (pencils 
of rays) of the meteor generally appear first in the north, forming an arch from 
east to west, having its vertex at the line of the magnetic meridian ; — that when 
this arch is yet only of low elevation, it is of considerable breadth from north 
to south, having the streamers of which it is composed placed cross-wise in re- 
lation to its own line, and all directed towards a point a little south of the 
zenith ; — that the arch moves forward towards the south, contracting its lateral 
dimensions as it approaches the zenith, and increasing in intensity of light by 
the shortening of the streamers near the magnetic meridian, and the gradual 
shifting of the angles, which the streamers near the east and west extremities of 
the arch make with its own line, till at length these streamers become parallel 
to that line, and then the arch is seen as a narrow belt, 3° or 4° only in breadth, 
stretching across the zenith at right angles to the magnetic meridian ; — that it 
still makes progress southwards ; and after it has reached several degrees south 
of the zenitli, again enlarges in breadth, by exhibiting an order of appear- 
ances the reverse of that which had attended its progress towards the zenith 
