soon becoming heated by the radiant heat cut off and absorbed by itself,
radiates that heat and causes the thermometer reading to return to about
its original amount. The false impression is thus produced that the
original radiated heat was unaffected by the vulcanite plate; instead of
which, as a matter of fact, the vulcanite plate had cut off the radiant
heat, becoming heated itself by so doing, and was consequently then the
radiating body affecting the thermometer.

The effect is similar in the case of induction between the two spirals.
Spiral A induces and spiral B receives the induced effect. The metal
plate being then interposed, cuts off and absorbs either all or part of
the inductive radiant energy emitted by A. The inductive radiant energy
thus cut off, however, is not lost, but is converted into electrical
energy in the metal plate, thereby causing it to become, as in the case
of the vulcanite in the heat experiment, a source of radiation which
compensates as far as spiral B is concerned for the original inductive
radiant energy cut off. The only material difference noticeable in
the two experiments is that in the case of heat the time that elapses
between the momentary fall in the thermometer reading (due to the
interception by the vulcanite plate of the radiant beat) and the
subsequent rise (due to the interposing plate, itself radiating that
heat) is long enough to render the effect clearly manifest; whereas in
the case of induction the time that elapses is so exceedingly short
that, unless special precautions are taken, the radiant energy emitted
by the metal plate is liable to be mistaken for the primary energy
emitted by the inducing spiral.

The current induced in the receiving spiral by the inducing one is
practically instantaneous; but on the interposition of a metal plate
the induced current which, as before described, is set up by the plate