Breaking a magnet
Weber considered that every molecule of a magnetic substance is itself a permanent magnet having two poles. He came to this conclusion by noticing that, when a magnet is broken in half, the two portions both have two poles, i.e., unlike poles have appeared on opposite sides of the break. No matter how many times a magnet is subdivided, each piece is found to possess two poles (Fig. 31.13). If this process could be carried out indefinitely, then, theoretically, single molecules would eventually be reached, and Weber thought it reasonable to suppose that these would also be magnets with two poles.
The effect of breaking a magnet may be verified by taking a length of clockspring and magnetizing it by some convenient method. The magnetized clockspring is broken up with the aid of a pair of pliers and the polarity of the broken pieces tested by obtaining repulsion with a known pole of a pivoted compass needle (see page 342).