MAGNETISM

4. The position of rest is different at different places, and different at the same place at distant periods of time. A great number of amusing toys have been formed of this substance, and the phenomena are often at first sight very surprising; but its application to the purposes of navigation renders it one of the most important discoveries ever made. The earlier navigators believed that it pointed always to the north pole of the world; and that therefore by means of it they could always at once tell the direction of therr meridian, and consequently in what direction they were sailing. It was hence called the loadstone, or leading stone. The employment of the loadstone itself for the purposes of navigation has long been laid aside; as artificial magnets can be constructed having a much greater intensity of directive power. See Magnetism. [s. 707]