90 Prof. Hansteeri on the Aurora Borealis. 
of the trees, which cover one another. If we hold a brush or a 
close heckle in such a manner that the bristles of the one or the 
teeth of the other are turned to the eye, round that place where 
the direction of the bristles or the teeth coincide with the axis of 
the eye, we can perceive the bottom of the brush or the heckle. 
In all other places, the bristles and the teeth cover one another, 
and conceal the bottom. If we now suppose a plane reaching the 
heavens, in the magnetic zenith which I have mentioned, and that 
the luminous columns shoot up perpendicularly to this plane, it 
will now be easy to perceive, from these examples, why the lu- 
minous mass can be seen through in these places, and forms a 
sort of corona, towards which all the beams seem to collect. 
When the arch of the aurora borealis rises so high in the sky as 
to reach the magnetic zenith, it seems then, at this place, to be 
broken off, from which we may infer, that the rings of the polar 
lights consist of very short luminous cylinders, parallel to the 
direction of the magnetism of the earth, which seem only to fonn 
one connected luminous mass, because the intermediate spaces 
are filled up by rows of luminous cylinders lying behind one an- 
other. We see also from this, that the shooting beams which 
seem to dart from the arch towards the zenith, properly neither 
come from the luminous ring, nor are connected with the lumi- 
nous columns, but that each of them, as well as the ring itself, 
consists of a great number of short luminous cylinders, lying 
close together, and almost parallel % of which each conceals a 
part of the one lying before it. 
I have already hinted, that there must be some connection 
between the aurora borealis and the magnetism of the earth. 
Besides the reasons which may be derived from the facts already 
mentioned, I mean, that the centre of the luminous rings coin- 
cide with the four magnetic poles ; and also, that the luminous 
columns shoot parallel to the medium direction of the magnetic 
powers at any one place ; that they, beyond all doubt, follow 
the laws of repulsion of the magnetic powers, and, consequent- 
ly, themselves are magnetic, — there are many other reasons as 
strong, if not stronger, of which I shall briefly mention only the 
most important. 
* They are not completely parallel, as their direction is parallel to the inclina- 
tion of the needle, which is diiferent in different places. 
