ce with a conductor,
equally long, insulated in the air; but it arises from a static
reaction, caused by the passage of an intense current through a
conductor well insulated, but surrounded outside its insulating coating
by a conducting body, such as sea-water or moist ground, or even by the
metallic envelope of iron wires placed in communication with the ground.
When this conductor is presented to one of the poles of a battery, the
other pole of which communicates with the ground, it becomes charged
with static electricity, like the coating of a Leyden-jar,--electricity
which is capable of giving rise to a discharge-current, even after the
voltaic current has ceased to be transmitted. Volta showed in one of his
beautiful experiments, that, in putting one of the ends of his pile
in communication with the earth, and the other with a non-insulated
Leyden-jar, the jar was charged in an instant of time to a degree
proportional to the force of the pile. At the same time an instantaneous
current was observed in the conductor between the pile and the jar,
which had all the properties of an ordinary current. Now it is evident
that the subaqueous wire with its insulating covering may be assimilated
exactly to an immense Leyden-jar. The glass of the jar represents the
gutta-percha; the internal coating is the surface of the copper wire;
the external coating is the surrounding metallic envelope and water. To
form an idea of the capacity of this new kind of battery, we have only
to remember that the surface of the wire is equal to fourteen square
yards per mile. Bringing such a wire into communication by one of its
ends with a battery, of which the opposite pole is in contact with the
earth, whilst the other extremity of the wire is insulated, must cause
the wire to take a charge of the same character and tension as that of
the pole of the battery touched by it.

These currents of static induction are proportional in intensity to
the force of the battery and the length of the wire, whilst an inverse
relation is true as regards the length of the conductor with the
ordinary voltaic current.

Professor Wheatstone proved, by actual experiment, that a continuous
current may be maintained in the circuit of the long wire of an
electric cable, of which one of the ends is insulated, whilst the other
communicates with one of the poles of a battery, whose other pole is
connected with the ground. This current he considers due to the uniform