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 degs., 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, [12] 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. 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 possible that the mixture of large bodies of fresh
and salt water may disturb the electrical equilibrium? Even during our
occasional visits to this part of South America, we heard of a ship,
two churches, and a house having been struck. Both the church and the
house I saw shortly afterwards: the house belonged to Mr. Hood, the
consul-general at Monte Video. Some of the effects were curious: the
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