ly
separated when we are examining into their nature; that is, into the
general law or laws under which their phenomena are produced. They appear
to me to consist in an action of contiguous particles dependent on the
forces developed in electrical excitement; these forces bring the particles
into a state of tension or polarity, which constitutes both _induction_ and
_insulation_; and being in this state, the continuous particles have a
power or capability of communicating their forces one to the other, by
which they are lowered, and discharge occurs. Every body appears to
discharge (444. 987.); but the possession of this capability in a _greater
or smaller degree_ in different bodies, makes them better or worse
conductors, worse or better insulators; and both _induction_ and
_conduction_ appear to be the same in their principle and action (1320.),
except that in the latter an effect common to both is raised to the highest
degree, whereas in the former it occurs in the best cases, in only an
almost insensible quantity.

1327. That in our attempts to penetrate into the nature of electrical
action, and to deduce laws more general than those we are at present
acquainted with, we should endeavour to bring apparently opposite effects
to stand side by side in harmonious arrangement, is an opinion of long
standing, and sanctioned by the ablest philosophers. I hope, therefore, I
may be excused the attempt to look at the highest cases of conduction as
analogous to, or even the same in kind with, those of induction and
insulation.

1328. If we consider the slight penetration of sulphur (1241. 1242.) or
shell-lac (1234.) by electricity, or the feebler insulation sustained by
spermaceti (1279. 1240.), as essential consequences and indications of
their _conducting_ power, then may we look on the resistance of metallic
wires to the passage of electricity through them as _insulating_ power. Of
the numerous well-known cases fitted to show this resistance in what are
called the perfect conductors, the experiments of Professor Wheatstone best
serve my present purpose, since they were carried to such an extent as to
show that _time_ entered as an element into the conditions of conduction[A]
even in metals. When discharge was made through a copper wire 2640 feet in
length, and 1/15th of an inch in diameter, so that the luminous sparks at
each end of the wire, and at the middle, could be observed in the same
place, the latter was found to b