"
[footnote] *Dove, in Poggend., 'Annalen', bd. xx., s. 341; bd. xix., s.
388. "The declination needle acts in very nearly the same way as an
atmospheric electrometer, whose divergence in like manner shows the
increased tension of the electricity before this has become so great as to
yield a spark." See also, the excellent observations of Professor K??wmtz,
in his 'Lehrbuch der Meteorologie', bd. iii., s. 511-519, and Sir David
Brewster, in his 'Treatise on Magnetism', p. 280. Regarding the magnetic
properties of the galvanic flame, or luminous arch from a Bunsen's carbon
and zinc battery, see Casselmann's 'Beobachtungen' (Marburg, 1844), s. 56-62.
The splendid appearance of colored polar light is the act of discharge, the
termination of a magnetic storm, as in an electrical storm a development of
light -- the flash of lightning -- indicates the restoration of the
disturbed equilibrium in the distribution of the electricity. An electric
storm is generally confined to a small space beyond the limits of which the
condition of the atmospheric electricity remains unchanged. A magnetic
storm, on the other hand,
p 193
shows its influence on the course of the needle over large portions of
continents, and, as Arago first discovered far from the spot where the
evolution of light was visible.
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