_The central point_ of the circuit--that point which divides between its
positive and negative halves--is reckoned, in practice, to be the
midway point in the line over which the current passes, in its whole
course from the positive post around to the negative post. When the
cords are of equal length, this point will always be in the person of
the patient, about midway between the parts where the two electrodes are
applied. This central point, or "point of centrality," is practically
neuter--neither positive nor negative; and upon the two opposite halves
of the circuit, the positive and negative _qualities_ of the current are
in greatest force nearest to the posts, and in least force nearest to
the central point. At this point they cease altogether, and the central
point is _neuter_.
It may, perhaps, be observed that, in _apparent_ contradiction of this
statement, the _sensational_ effect of the current on the negative half
of the circuit is _least_ nearest to the positive post, and becomes
regularly _greater_ as the current advances towards the central point;
and that _at_ this point it is greater than at any other point between
this and the positive post. To relieve this seeming contradiction, it is
only necessary to consider that, in fact, the _positive_ state on the
negative half of the current _does_ increase regularly from the
positive post to the central point. But that which is the _increase_ of
the positive state is the _decrease_ of the negative state. So it is
still true that on the negative half of the circuit, the _negative_
qualities _diminish_ as we advance towards the central point just as on
the positive half, the _positive_ qualities diminish regularly towards
the central point, as stated above.