es, was eighteen feet
long: the terminal pieces were one-fifth of an inch in diameter, and each
six inches long. This was compared with nineteen feet in length of copper
wire one-fifth of an inch in diameter. The bundle gave a smaller spark on
breaking contact than the latter, even when its strands were held together
by string: when they were separated, it gave a still smaller spark. Upon
the whole, however, the diminution of effect was not such as I expected:
and I doubt whether the results can be considered as any proof of the truth
of the supposition which gave rise to them.

1113. The inductive force by which two elements of one current (1109.
1110.) act upon each other, appears to diminish as the line joining them
becomes oblique to the direction of the current and to vanish entirely when
it is parallel. I am led by some results to suspect that it then even
passes into the repulsive force noticed by Ampere[A]; which is the cause of
the elevations in mercury described by Sir Humphry Davy[B], and which again
is probably directly connected with the quality of intensity.

[A] Recueil d'Observations Electro-Dynamiques, p. 285.

[B] Philosophical Transactions, 1823, p. 155.

1114. Notwithstanding that the effects appear only at the making and
breaking of contact, (the current remaining unaffected, seemingly, in the
interval,) I cannot resist the impression that there is some connected and
correspondent effect produced by this lateral action of the elements of the
electric stream during the time of its continuance (60. 242.). An action of
this kind, in fact, is evident in the magnetic relations of the parts of
the current. But admitting (as we may do for the moment) the magnetic
forces to constitute the power which produces such striking and different
results at the commencement and termination of a current, still there
appears to be a link in the chain of effects, a wheel in the physical
mechanism of the action, as yet unrecognised. If we endeavour to consider
electricity and magnetism as the results of two forces of a physical agent,
or a peculiar condition of matter, exerted in determinate directions
perpendicular to each other, then, it appears to me, that we must consider
these two states or forces as convertible into each other in a greater or
smaller degree; i.e. that an element of an electric current has not a
determinate electric force and a determinate magnetic force constantly
existing in the same ratio,