88 
Prof. Hansteen on the Aurora Borealis, 
whicfi^ so far as we have hitherto been able to determine^ coincide 
with the magnetic poles of the earth. The larger luminous ring 
IS formed round the two opposite poles of the stronger magnetic 
axis in North America and New Holland. Whether a similar 
ring, as full and as regular, be formed round the poles of the 
weaker axis in Siberia and Terra del Fuego, is a matter which, 
from the few observations we are able to collect, cannot yet be 
so well ascertained. 
The arch of the polar light is seldom seen without luminous 
beams shooting out from it. From the side of the arch turned 
away from the Pole, beams or rather columns of light dart forth 
in a direction nearly perpendicular to the arch, and ascend to- 
wards the zenith. If these beams are so long as to pass a con- 
siderable way beyond the zenith, towards the south, they form, 
in the neighbourhood of the zenith, a kind of corona or glory, 
which seems to be the point of their union. This corona lies 
from 15° to 20° south of the zenith, in such a situation that if 
we suppose a vertical plane passing through the highest point of 
-the arch, which with us lies about 20° west from the meridian, 
and produced so as to pass through the zenith, it will come ex- 
actly upon the middle of the corona. And it is a very remark- 
able circumstance, that the distance (f this corona from the 
southern horizon^ is eocactlij equal to the inclination of the needle 
at the place ; so that the south pole f the needle 'points directly 
to the centre of the corona. Such I found to be the case with 
regard to a pretty full aurora borealis, on the 7th of October 
1816. The height of the crown was 73° 10' ; its eastern azi- 
muth 12° 11'. With regard to another, on the 8th February 
1817, the height of the corona was 74° 39'; its east azimuth 
14° 57'. Now, in .Christiania, the variation of the compass is 
20°, and the inclination of the needle about 73°. It will be un- 
derstood, of course, tliat we cannot determine, with perfect ex- 
actness, the situation of so changing a mass of light; and that, 
therefore, the small deviations from the direction of the needle 
cannot be taken into account. At the moment when the corona 
is formed, and the whole heavens have the appearance of a 
brilliant cupola, supported by columns of different coloured 
light, the aurora borealis displays its full beauty and majesty. 
Such exhibitions of these lights, which, in the. period from 1720, 
