The Electric Ball
Provide a ball of cork about three-quarters of an inch in diameter,
hollowed out in the internal part by cutting it in two hemispheres,
scooping out the inside, and then joining them together with paste.
Having attached this to a silk thread between three and four feet in
length, suspend it in such a manner that it may just touch the knob of
an electric jar, the outside of which communicates with the ground. On
the first contact it will be repelled to a considerable distance, and
after making several vibrations, will remain stationary; but if a
candle be placed at some distance behind it, so that the ball may be
between it and the bottle, the ball will instantly begin to move, and
will turn round the knob of the jar, moving in a kind of ellipsis as
long as there is any electricity in the bottle. This experiment is
very striking, though the motions are far from being regular; but it
is remarkable that they always affect the elliptical rather than the
circular form.