His conclusion is that there exist lines of force within
the magnet of the same nature as those without. What is more, they
are exactly equal in amount to those without. They have a relation
in direction to those without; and in fact are continuations of
them.... 'Every line of force, therefore, at whatever distance it
may be taken from the magnet, must be considered as a closed
circuit, passing in some part of its course through the magnet,
and having an equal amount of force in every part of its course.'
All the results here described were obtained with moving metals.
'But,' he continues with profound sagacity, 'mere motion would not
generate a relation, which had not a foundation in the existence of
some previous state; and therefore the quiescent metals must be in
some relation to the active centre of force,' that is to the magnet.
He here touches the core of the whole question, and when we can
state the condition into which the conducting wire is thrown before
it is moved, we shall then be in a position to understand the
physical constitution of the electric current generated by its
motion.
In this inquiry Faraday worked with steel magnets, the force of
which varies with the distance from the magnet. He then sought a
uniform field of magnetic force, and found it in space as affected
by the magnetism of the earth. His next memoir, sent to the Royal
Society, December 31, 1851, is 'on the employment of the Induced
Magnetoelectro Current as a test and measure of magnetic forces.
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