THE AURORA. 
like form. The visible portion of this arc soon be- 
comes surrounded with a pale light, followed by the 
formation of other concentric arcs: next come jets and 
colored rays from the dark part of the segment, break- 
ing up its continuity, and indicating a general move- 
ment throughout its mass — "internal shocks," as Lard- 
ner calls them — which issue from it as flames from a 
conflagration. 
Lottin's observations at Bossekop, in Finland, lati- 
tude 70°, which embrace no less than a hundred and 
forty-five exhibitions, begin with a " tinting of the 
constantly prevailing sea-fog," the upper border of 
which was fringed with auroral light. 
If these, and the more familiar accounts of the au- 
rora in the middle United States, be taken as good 
types of this phenomenon, I would say that the ma- 
tured Arctic aurora resembled their incipient stages; 
but that the same law of correspondence, which marks 
the centre of the segment in or about the magnetic 
axis, gave to us, situated as we were in the immediate 
proximity of the magnetic pole of our earth, the strange 
spectacle of a complete arch passing through or near 
the zenith, and embracing an amplitude of nearly 
one hundred and eighty degrees. The zone or band- 
like character of this auroral arch was its pervading 
characteristic. It seldom exceeded thirty, and was 
generally within ten degrees in width, a floating, wav- 
ing band of nebulous illumination. 
The likeness between some of the auroral appear- 
ances and a lower range of meteorological phenomena 
has been repeatedly noticed. The handes polaires of 
Humboldt, the plaques aurorales of Lottin, the cirro- 
cumulated resemblances of Hood and Richardson, are 
among these : and I have alluded more than once my- 
