or by some intermediate agency, as in the case of light, heat,
the electric current, and (as I believe) static electric action.
The idea of magnetic fluids, as applied by some, or of Magnetic centres
of action, does not include that of the latter kind of transmission,
but the idea of lines of force does.' And he continues thus:--
'I am more inclined to the notion that in the transmission of the
[magnetic] force there is such an action [an intermediate agency]
external to the magnet, than that the effects are merely attraction
and repulsion at a distance. Such an affection may be a function of
the ether; for it is not at all unlikely that, if there be an ether,
it should have other uses than simply the conveyance of radiations.'
When he speaks of the magnet in certain cases, 'revolving amongst
its own forces,' he appears to have some conception of this kind in
view.

A great part of the investigation completed in October, 1851, was
taken up with the motions of wires round the poles of a magnet and
the converse. He carried an insulated wire along the axis of a bar
magnet from its pole to its equator, where it issued from the magnet,
and was bent up so as to connect its two ends. A complete circuit,
no part of which was in contact with the magnet, was thus obtained.
He found that when the magnet and the external wire were rotated
together no current was produced; whereas, when either of them was
rotated and the other left at rest currents were evolved. He then
abandoned the axial wire, and allowed the magnet itself to take its
place; the result was the same.[2] It was the relative motion of
the magnet and the loop that was effectual in producing a current.

The lines of force have their roots in the magnet, and though they
may expand into infinite space, they eventually return to the magnet.