I have the following experiments to communicate: I held in one hand a
wire, which was fastened at the other end to the handle of a pump, in
order to try whether the stroke from the prime conductor, through my
arms, would be any greater than when conveyed only to the surface of
the earth, but could discover no difference.
I placed the needle of a compass on the point of a long pin, and
holding it in the atmosphere of the prime conductor, at the distance
of about three inches, found it to whirl round like the flyers of a
jack, with great rapidity.
I suspended with silk a cork ball, about the bigness of a pea, and
presented to it rubbed amber, sealing-wax, and sulphur, by each of
which it was strongly repelled; then I tried rubbed glass and china,
and found that each of these would attract it, until it became
electrified again, and then it would be repelled as at first; and
while thus repelled by the rubbed glass or china, either of the
others when rubbed would attract it. Then I electrified the ball,
with the wire of a charged phial, and presented to it rubbed glass
(the stopper of a decanter) and a china tea-cup, by which it was as
strongly repelled as by the wire; but when I presented either of the
other rubbed electrics, it would be strongly attracted, and when I
electrified it by either of these, till it became repelled, it would
be attracted by the wire of the phial, but be repelled by its coating.
These experiments surprised me very much, and have induced me to
infer the following paradoxes.
1. If a glass globe be placed at one end of a prime-conductor, and
a sulphur one at the other end, both being equally in good order,
and in equal motion, not a spark of fire can be obtained from the
conductor; but one globe will draw out, as fast as the other gives in.
2. If a phial be suspended on the conductor, with a chain from its
coating to the table, and only one of the globes be made use of at
a time, 20 turns of the wheel, for instance, will charge it; after
which, so many tarns of the other wheel will discharge it; and as
many more will charge it again.
3. The globes being both in motion, each having a separate conductor,
with a phial suspended on one of them, and the chain of it fastened
to the other, the phial will become charged; one globe charging
positively, the other negatively.
4. The phial being thus charged, hang it in like manner on the other
conductor; set both wheels a going again, and the same number of
turns that charged it before, will now discharge it; and the same
number repeated, will charge it again.
5. When each globe communicates with the same prime conductor, having
a chain hanging from it to the table, one of them, when in motion
(but which I cannot say) will draw fire up through the cushion, and
discharge it through the chain; the other will draw it up through the
chain, and discharge it through the cushion.
I should be glad if you would send to my house for my sulphur globe,
and the cushion belonging to it, and make the trial; but must caution
you not to use chalk on the cushion, some fine powdered sulphur will
do better. If, as I expect, you should find the globes to charge the
prime conductor differently, I hope you will be able to discover some
method of determining which it is that charges positively.