halves of the ring. Connecting the ends of one of the coils with a
galvanometer, he found that the moment the ring was magnetised, by
sending a current through the other coil, the galvanometer needle
whirled round four or five times in succession. The action,
as before, was that of a pulse, which vanished immediately.
On interrupting the circuit, a whirl of the needle in the opposite
direction occurred. It was only during the time of magnetization or
demagnetization that these effects were produced. The induced
currents declared a change of condition only, and they vanished the
moment the act of magnetization or demagnetization was complete.

The effects obtained with the welded ring were also obtained with
straight bars of iron. Whether the bars were magnetised by the
electric current, or were excited by the contact of permanent steel
magnets, induced currents were always generated during the rise,
and during the subsidence of the magnetism. The use of iron was then
abandoned, and the same effects were obtained by merely thrusting a
permanent steel magnet into a coil of wire. A rush of electricity
through the coil accompanied the insertion of the magnet; an equal
rush in the opposite direction accompanied its withdrawal.
The precision with which Faraday describes these results, and the
completeness with which he defines the boundaries of his facts,
are wonderful. The magnet, for example, must not be passed quite
through the coil, but only half through; for if passed wholly
through, the needle is stopped as by a blow, and then he shows how
this blow results from a reversal of the electric wave in the helix.
He next operated with the powerful permanent magnet of the Royal
Society, and obtained with it, in an exalted degree, all the
foregoing phenomena.