Besides the four tubes
which I found vertical, and traced beneath the surface, there were
several other groups of fragments, the original sites of which
without doubt were near. All occurred in a level area of shifting
sand, sixty yards by twenty, situated among some high
sand-hillocks, and at the distance of about half a mile from a
chain of hills four or five hundred feet in height. The most
remarkable circumstance, as it appears to me, in this case as well
as in that of Drigg, and in one described by M. Ribbentrop in
Germany, is the number of tubes found within such limited spaces.
At Drigg, within an area of fifteen yards, three were observed, and
the same number occurred in Germany. In the case which I have
described, certainly more than four existed within the space of the
sixty by twenty yards. As it does not appear probable that the
tubes are produced by successive distinct shocks, we must believe
that the lightning, shortly before entering the ground, divides
itself into separate branches.
The neighbourhood of the Rio Plata seems peculiarly subject to
electric phenomena. In the year 1793, one of the most destructive
thunderstorms perhaps on record happened at Buenos Ayres:
thirty-seven places within the city were struck by lightning, and
nineteen people killed.
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