84 Prof. Hansteen on the Aurora Borealis. 
appears a luminous arch, the convex side of which is turned tt? 
the zenith, and the extremities of which bend towards the horr- 
zon. That part of the circle of the horizon which lies between 
its extremities forms a chord of the arch. The segment of the 
' circle between the arch and the horizon is, for the most part', 
darker than the rest of the sky; sometimes black, sometimes 
“dark-grey. The farther you advance towards the north j this 
' coloured segment becomes less dark, and in the highest latitudes 
it becomes altogether undistinguishable. The highest point of 
the arch, at least in latitudes not very high, is almost always 
found in the magnetic meridian, that vertical plane which passes 
through the magnetic pole. In the North American States, 
where the westerly variation of the needle is only two degrees, 
tlio same luminous arch is seen, but its highest point lies due 
north. According to Scoresby’s observations *, on the east coast 
of Greenland, in Lat. 65° N., the arch of the Aurora Borealis 
lies from north to south, in such a manner that its highest point 
is either to the east or west, as the arch lies on the one side or 
tlie other of the zenith. This agrees with the remarks of the 
missionary Andrew Ginge on the aurora borealis, in the colony 
of Good Hope, in Greenland (Lat. 64° 10'" 5') ; with this 
difference only, that the arch commonly appears low in the east 
or south-east, and more seldom approaches near to the zenith'. 
He describes in the following manner such an arch, as seen on 
the 12 th December 1786. “At half-past 4 p. m. the first faint 
•dashes of the aurora borealis arose from the east, which a 
quarter of an- hour after reached the zenith, and from that shot 
out on all sides. Soon after, these were converted into an arch, 
which went through the zenith, and almost touched the horizon 
in the north and south. This arch was white, and so brilliant 
that it lighted up Baals River, which is a mile broad. At 7 p. m; 
the declination had decreased, from mid-day, from 50° 57 to 
50° 37', that is, 20P. At half-past 8 the arch disappeared, and 
in the south was seen a comb with its teeth upwards. At that 
time the declination was 50° 20',” &c. 
From the foregoing observations, it is easy to see that this 
arch must be a part of a whole luminous ring, hovering over the 
surface of the earth at a considerable height, of which every ob- 
• Scoresby’s Journal of a Voyage to Greenland, 
