These disturbances vary in
intensify, but they never fail to take place, and are manifested even
in places in which the aurora borealis is not visible. This
coincidence, proved by M. Arago without any exception, during several
years of observation, is such that the learned Frenchman was able,
without ever having been mistaken, to detect from the bottom of the
cellars of the observatory of Paris the appearance of an aurora
borealis. M. Matteucci had the opportunity of observing this magnetic
influence under a new and remarkable form. He saw, during the
appearance of the aurora borealis of November 17, 1848, the soft iron
armatures employed in the electric telegraph between Florence and Pisa
remain attached to their electro-magnets, as if the latter were
powerfully magnetized, without, however, the apparatus being in action,
and without the currents in the battery being set in action. This
singular effect ceases with the aurora, and the telegraph, as well as
the batteries, could operate anew, without having suffered any
alteration. Mr.
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