current causes it to overshoot its original position, and for an instant
the charge of the jar is reversed. The current now flows backwards in
the same way that the lath returned back, and charges the jar as at
first. This discharging and recharging continue backward and forward, so
to speak, until all the energy which was originally given to the jar has
been expended, and it resumes its normal condition. In this experiment
the elasticity and inertia of the Aether have both been called into
play, so that we see in this electrical experiment a similar
illustration of the elasticity and inertia of the Aether, as manifested
in the undulatory or wave theory of light. The question now arises, what
are the corresponding properties as given by Maxwell in his
electro-magnetic theory? In Art. 782 he writes: "In the theory of
electricity and magnetism adopted in this treatise two forms of energy
are recognized--the electro-static and the electro-kinetic--and these
are supposed to have their seat, not merely in the electrified or
magnetized bodies, but in every part of the surrounding space where
electric or magnetic force is observed to act. Hence our theory agrees
with the undulatory theory in assuming the existence of a medium which
is capable of becoming a receptacle of two forms of energy." Faraday, in
his _Experimental Researches_, paragraph 3075, in referring to the
character of magnetic phenomena external to the magnet, writes: "I am
more inclined to the notion that in the transmission of force there is
such an action external to the magnet, than that the effects are merely
attraction and repulsion at a distance. Such a function may be a
function of the Aether if it should have other uses than simply the
conveyance of radiations" (light and heat). From this extract we learn
that Faraday was also of the opinion that the Aether around a magnet or
any electrified body was directly concerned in the propagation of the
electric and magnetic forces, these forces according to Maxwell being of
two kinds. From the illustration of the charging and discharging of the
Leyden jar, we learn that aetherial electrical waves can be produced by
electric means, and from the alternate charging and recharging of the
jar we learn that these aetherial waves travel to and from the jar with
a periodic wave motion. Here, therefore, we have an aetherial wave
motion which is produced wholly by electricity, and yet which answers
our definition of a wav