_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. THE ELECTRIC CIRCUIT.