t the
strongest battery in Paris was used, and that its power on a
substance of such easy fusibility as glass was to form tubes so
diminutive, we must feel greatly astonished at the force of a shock
of lightning, which, striking the sand in several places, has
formed cylinders, in one instance of at least thirty feet long, and
having an internal bore, where not compressed, of full an inch and
a half; and this in a material so extraordinarily refractory as
quartz!

The tubes, as I have already remarked, enter the sand nearly in a
vertical direction. One, however, which was less regular than the
others, deviated from a right line, at the most considerable bend,
to the amount of thirty-three degrees. From this same tube, two
small branches, about a foot apart, were sent off; one pointed
downwards, and the other upwards. This latter case is remarkable,
as the electric fluid must have turned back at the acute angle of
26 degrees, to the line of its main course. 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. (3/12. Azara's "Voyage" volume 1 page 36.)
From facts stated in several books of travels, I am inclined to
suspect that thunderstorms are very common near the mouths of great
rivers. Is it not po