expression of the real condition of things, for the lines are only
symbols for a condition of strain in a medium which cannot be
represented in thought, as we know nothing of its real nature. There
is one point in this connection which I must emphasize. The strained
lines, Fig. 1, are indications of stored energy in the ether, and the
lines _cannot_ disappear without giving out that energy. Ordinarily,
it makes its appearance as the extra current, and adds itself so as to
prolong the current which extended the lines when an attempt is made
to cut off such current. Were it conceivable that the current could be
cut off and the wire put on open circuit while the lines still
remained open or strained, the energy must still escape when the field
disappears. It would then produce such a high potential as to be able
to discharge from the ends of the conductor, and if the conductor were
of some section, part of the energy would be expended in setting up
local currents in it. The field could not disappear without an outlet
for the energy it represents. But we cannot cut off a current in a
wire so as to leave the wire on open circuit with the lines of the
magnetic circuit remaining around it without iron or steel or the like
in the magnetic circuit. We can approach that condition, however, by
breaking the circuit very quickly with a condenser of limited capacity
around the break. This is done in the Ruhmkorff coil primary; the
condenser forms a sort of blind alley for the extra current on its
beginning to flow out of the primary coil. But the condenser charges
and backs up and stops the discharge from the primary, even giving a
reverse current. The lines of magnetic force collapse, however, and
have their effect in the enormous potential set up in the secondary
coil.

Take away the secondary coil so as to stop that outlet, the energy
expends itself on the iron core and the primary coil. Take away the
iron core, and the energy of magnetization of the air or ether core
expends itself on the wire of the primary and, possibly, also on the
dielectric of the condenser to some extent. The extra current becomes
in this instance an oscillatory discharge of very high period back and
forth through the primary coil from the condenser, until the energy is
lost in the heat of C2 x R. This conversion is doubtless rendered
all the more rapid by uneven distribution of current and eddy current
set up in the wire of the coil.

The considerations