nected with a
galvanometer. No effect whatever was observed. But though quiescent
water gave no effect, moving water might. He therefore worked at London
Bridge for three days during the ebb and flow of the tide, but without
any satisfactory result. Still he urges, "Theoretically it seems a
necessary consequence, that where water is flowing there electric
currents should be formed. If a line be imagined passing from Dover to
Calais through the sea, and returning through the land, beneath the
water, to Dover, it traces out a circuit of conducting matter one part
of which, when the water moves up or down the channel, is cutting the
magnetic curves of the earth, while the other is relatively at rest....
There is every reason to believe that currents do run in the general
direction of the circuit described, either one way or the other,
according as the passage of the waters is up or down the channel." This
was written before the submarine cable was thought of, and he once
informed me that actual observation upon that cable had been found to be
in accordance with his theoretic deduction.

Three years subsequent to the publication of these researches, that is
to say on January 29, 1835, Faraday read before the Royal Society a
paper "On the influence by induction of an electric current upon
itself." A shock and spark of a peculiar character had been observed by
a young man named William Jenkin, who must have been a youth of some
scientific promise, but who, as Faraday once informed me, was dissuaded
by his own father from having anything to do with science. The
investigation of the fact noticed by Mr. Jenkin led Faraday to the
discovery of the _extra current_, or the current _induced in the primary
wire itself_ at the moments of making and breaking contact, the
phenomena of which he described and illustrated in the beautiful and
exhaustive paper referred to.

Seven and thirty years have passed since the discovery of
magneto-electricity; but, if we except the _extra current_, until quite
recently nothing of moment was added to the subject. Faraday entertained
the opinion that the discoverer of a great law or principle had a right
to the "spoils"--this was his term--arising from its illustration; and
guided by the principle he had discovered, his wonderful mind, aided by
his wonderful ten fingers, overran in a single autumn this vast domain,
and hardly left behind him the shred of a fact to be gathered by his
successors.

An