measure or bore of the lightning (if such a term may be used)
must have been about one inch and a quarter. At Paris, M.
Hachette and M. Beudant [11] succeeded in making tubes, in
most respects similar to these fulgurites, by passing very
strong shocks of galvanism through finely-powdered glass:
when salt was added, so as to increase its fusibility, the tubes
were larger in every dimension, They failed both with
powdered felspar and quartz. One tube, formed with
pounded glass, was very nearly an inch long, namely .982,
and had an internal diameter of .019 of an inch. When we
hear that 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 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