It may be proper, in this place, to spend a few words upon electrical
polarization in general.
_Electrical polarity_ may be defined as a characteristic of the electric
or magnetic fluid, by virtue of which its opposite qualities, as those
of _attraction_ and _repulsion_ towards the same object, are manifested
in opposite parts of the electric or magnetic body. These opposite parts
are called the _poles_ of the body, as the _positive_ and _negative_
poles. The difference between the positive and negative poles is
believed to be that of _plus_ and _minus_--plus being positive and minus
negative. This is the Franklinian view, and, if I mistake not, is the
one most in favor with men of science at the present day. This view
supposes that the electricity or magnetism arranges itself in _maximum_
quantity and intensity at the one extremity or pole of the magnetized
body, and in _minimum_ quantity and intensity at the opposite extremity
or pole; and that, between these points--the maximum and the
minimum--the fluid is distributed, in respect to quantity and intensity,
upon a scale of regular graduation from the one to the other. The idea
may be represented by a _line_, commencing in a _point_ at the one end,
and extending, with regularly increasing breadth, to the other end. The
larger end would represent the positive pole, and the smaller, the
negative pole. Or perhaps a better representation of the magnet would be
a line of equal breadth from end to end, but having the one end _white_,
or slightly tinted, say, with _red_, and the color gradually and
regularly increasing in strength to the other end, where it becomes a
_deep scarlet_. Let the coloring-matter represent the magnetism in the
body charged, and we have the magnet illustrated in its polarization:
the deep-red end is the positive pole, and the white or faintly-colored
end is the negative pole.
It is a law of polarization that the positive poles of different magnets
repel each other, and the negative poles repel each other; while
positive and negative poles attract each other. The same law of
polarization rules in electric or magnetic _currents_ as in magnets at
rest.