120 
to ; and as often, afterwards, as I happened to remark the 
same appearances, but my attention was never so much, 
nor from its nature, so often directed to this as to the noc- 
turnal phenomenon; and I do not, from my own experience, 
speak of it with the same confidence — but I cannot resist 
the conclusion that it is the same meteor, only presenting a 
different appearance as seen at night, and in bright sun- 
light. 
From the frequency with which the aurora was at one 
time brought before me, I was gradually led to form some 
theory explanatory of its nature, and of the weather changes 
I had observed to succeed it, which I here submit, with 
diffidence, for consideration. 
I would first notice a remark made, if I recollect aright, 
by Sir J ohn Ross, the Arctic navigator, that the aurora was 
confined to the lower (or lowest ) regions of the atmosphere. 
That this should be the case in very high northern lati- 
tudes, would be quite in accordance with the theory I have 
formed. That the reverse is the case in our own country 
may be inferred from the appearances in Inverness-shire, 
and in England in November, 1848 ; — and, I believe, from 
many similar phenomena being observed, at the same times, 
over wide ranges of the lower latitudes. But this, if cor- 
rect, is equally in accordance with the theory. 
In explanation, I will suppose it may be assumed that 
the air passes from the poles towards the Equator ; where, 
being rarified, it rises, and, in considerable degree, at least, 
returns back to the poles, in the higher regions of the 
atmosphere. 
This general circulation is, no doubt, much modified nearer 
the surface of the globe, by large islands, chains of moun- 
tains, and more especially by extensive continents, as they are 
heated or cooled down by the comparative presence or absence 
of the sun s rays. But where not influenced by such cases, and 
in those latitudes where they have room to expand and find 
