Or, again, a similar shock
may be experienced by a person standing within the negative zone on the
neutralization of the charge.
I may take the opportunity here to mention a highly interesting and
instructive incident observed on local telegraph circuits during a
thunderstorm. The storm may be taking place at some distance from the
point of observation. The electrified cloud induces the opposite charge
beneath it, the similar charge being repelled. It is noticeable that the
needle of a galvanometer, starting from the middle position, goes
gradually over to one side, eventually indicating a considerable
deflection. Suddenly, owing apparently to a lightning discharge some
distance away, the force which caused the deflection is withdrawn, and the
needle rebounds with great violence to the opposite side. In a short time,
the cloud becoming again charged on its under surface, and recommencing
its inductive effect upon the adjacent earth, the needle starts again, and
goes through the same series of movements, a violent counterthrow
following every flash of lightning.
If we can so far control our imagination, we may conceive the earth to be
one large insulated conductor, susceptible to every influence around it.
If then the earth, as a mass of matter, behaves as above indicated, there
is no plausible reason for declining to regard any other large conducting
mass in a similar light, and as a body capable of being subjected more or
less completely to the various impulses affecting the earth.
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