De la Rive, from whose admirable treatise upon Electricity we have
borrowed our general views, and whose theory we have attempted to
illustrate in this paper, concludes that the aurora borealis is a
phenomenon which has its seat in the atmosphere, and consists in the
production of a luminous ring of greater or less diameter, having for
its centre the magnetic pole. Experiment shows, as we have seen, that,
on bringing about in rarefied air the reunion of the two electricities,
near the pole of a powerful artificial magnet, a small luminous ring is
produced, similar to that which constitutes the aurora borealis, and
animated by a similar movement of rotation. The aurora borealis would
be due, consequently, to electric discharges taking place in the polar
regions between the positive electricity of the atmosphere and the
negative electricity of the earth. These electric discharges taking
place constantly, but with intensities varying according to the state
of the atmosphere, the aurora borealis should be a daily phenomenon,
more or less intense, consequently visible at greater or less
distances, but only when the nights are clear,--which is perfectly in
accordance with observation.
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