REPORT ON METEOROLOGY. 
255 
The opinions of Mr. Dalton on the height of the aurora 
have not been received without contest. Mr. Farquharson 
of Alford in Aberdeenshire has published his views upon this 
subject in a paper containing many curious facts, and from 
which he draws the conclusion that the aurora is not elevated 
above one or two miles *. His estimate however appears to me 
to be founded on a species of observations somewhat vague, 
and by no means comparable, as scientific deductions, to the 
trigonometrical measures of Mr. Dalton. Indeed, the fact of 
the immense distances of points at which these arches have 
been seen at the same instant, is alone sufficient to throw 
great doubt upon any theory which assigns to them a low 
position in the atmosphere. So strong is this objection, that 
Mr. Farquharson has been obliged to suppose that the different 
observers were viewing differ'ent parallel auroral bands,—a sup¬ 
position surrounded with difficulties. The only striking actually 
observed fact appearing to demonstrate that the aurora some¬ 
times approaches the surface of the earth, is that, related by 
Captain Parry, of a beam of the aurora appearing to shoot down 
between the observers and a rising ground only 3000 feet off f. 
This very extraordinary and unique observation, certainly ap¬ 
pears to me more attributable to an optical illusion, than as 
fitted to become the basis of extensive induction. At least it 
is very conceivable that a beam of the aurora shooting down¬ 
wards , as is described, with all the brilliancy peculiar to that 
meteor in arctic climates, might, as it passed behind an eminence, 
appear from the quickness of its motion to continue its former 
course, and shoot across the obstacle which actually intercepted 
it from view. Such at least seems to me a highly natural ex¬ 
planation :—be this as it may, a single observation cannot, in 
the face of all those to the contrary, limit the bounds of the 
aurora to the lower strata of the atmosphere. 
I readily admit, however, that some phenomena of electrically 
illuminated clouds,such as I remember particularly to have obser¬ 
ved on the 10th Sept. 1827J, are of difficult explanation. Should 
it, however, be admitted that these were “ clouds highly electri¬ 
fied,” as I have stated in the memorandum just referred to, I 
would beg to draw a very broad line between these and true 
auroral nebulae or arches. The evidence which convinced me 
that these were truly clouds, was especially the fact that “ they 
Prof. Moll, in the Royal Institution Journal , N.S. vol. i. On that of 1828, Mr. 
Gilbert, Phil. May. N.S. iv. 453; Capt. Kater, Ibid. 337 ; Mr. Harvey, Edin. 
Journal of Science, x. 146. 
* Phil. Trans. 1829, p. 105. f Parry’s Third Voyage. 
J Edinb. Journal of Science , ix. 138. 
