' This was only a
prediction, for the experiment was not made.[2] Sixteen years
subsequently, however, the proper conditions came into play, and
Faraday was able to show that the observations of Werner Siemens,
and Latimer Clark, on subterraneous and submarine wires were
illustrations, on a grand scale, of the principle which he had
enunciated in 1838. The wires and the surrounding water act as a
Leyden jar, and the retardation of the current predicted by Faraday
manifests itself in every message sent by such cables.
The meaning of Faraday in these memoirs on Induction and Conduction
is, as I have said, by no means always clear; and the difficulty
will be most felt by those who are best trained in ordinary
theoretic conceptions. He does not know the reader's needs, and he
therefore does not meet them. For instance he speaks over and over
again of the impossibility of charging a body with one electricity,
though the impossibility is by no means evident. The key to the
difficulty is this. He looks upon every insulated conductor as the
inner coating of a Leyden jar. An insulated sphere in the middle of
a room is to his mind such a coating; the walls are the outer coating,
while the air between both is the insulator, across which the charge
acts by induction. Without this reaction of the walls upon the
sphere you could no more, according to Faraday, charge it with
electricity than you could charge a Leyden jar, if its outer coating
were removed.
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