Fig. 196.
A loadstone mounted in brass or silver, with the iron cheeks b b attached. c. The bit of soft iron called the armature.
Second Experiment.
If a needle of tempered steel (fitted with a little brass cup in the centre to work upon a point) is rubbed with the loadstone in one direction only, it is rendered permanently magnetic, and will now be found to take a certain fixed position, pointing always in a direction due north and south. The end which points towards the north is called the north pole, and the other extremity the south pole, and it is usual to mark the north pole with an indent or scratch to distinguish it at all times.
Third Experiment.
If another bar of steel is magnetized, and the north pole duly marked, and then brought towards the same pole of the suspended magnet, instant repulsion takes place; the magnet, of course, grasped in the hand is not free to move, but the small magnet immediately shows the same fact noticed with electricity, viz., "that similar magnetisms repel." Two north poles repel each other, but when the bar of steel is reversed, the opposite effect occurs, and the suspended magnet is attracted, showing that dissimilar magnetisms attract, and a north will attract a south pole. (Fig. 197.)
Fig. 197.
A magnetic needle, the north pole n being attracted to the south pole of the bar magnet s, and repelled from the north end.