quantity, of the electricity excited by a machine, and that from a voltaic
pile; for the purpose not only of confirming their identity (378.), but
also of demonstrating certain general principles (366, 377, &c.), and
creating an extension of the means of investigating and applying the
chemical powers of this wonderful and subtile agent.

362. The first point to be determined was, whether the same absolute
quantity of ordinary electricity, sent through a galvanometer, under
different circumstances, would cause the same deflection of the needle. An
arbitrary scale was therefore attached to the galvanometer, each division
of which was equal to about 4°, and the instrument arranged as in former
experiments (296.). The machine (290.), battery (291.), and other parts of
the apparatus were brought into good order, and retained for the time as
nearly as possible in the same condition. The experiments were alternated
so as to indicate any change in the condition of the apparatus and supply
the necessary corrections.

363. Seven of the battery jars were removed, and eight retained for present
use. It was found that about forty turns would fully charge the eight jars.
They were then charged by thirty turns of the machine, and discharged
through the galvanometer, a thick wet string, about ten inches long, being
included in the circuit. The needle was immediately deflected five
divisions and a half, on the one side of the zero, and in vibrating passed
as nearly as possible through five divisions and a half on the other side.

364. The other seven jars were then added to the eight, and the whole
fifteen charged by thirty turns of the machine. The Henley's electrometer
stood not quite half as high as before; but when the discharge was made
through the galvanometer, previously at rest, the needle immediately
vibrated, passing _exactly_ to the same division as in the former instance.