The force furnished by the magnet — magnetic polarity—produces distinct effects when applied to plants and to animals, and it has been utilized in the treatment of diseases. It has been shown by Dr. Vansant that the south pole of the magnet applied to a sensitive surface causes pain, while the north pole is free from this action, and indeed relieves the pain caused by the former. Small animals are similarly affected, the south pole causing excitement, and the north pole sedation. Sometimes remarkable curative results are obtained by the application of magnets in neuralgia and in chorea; but they often fail utterly. In hysterical affections, hemi-ancBsthesia, contractures, etc., the results are more constant, and, indeed, are often very striking. It is quite impossible to separate the influences due to the imagination from the direct action of the magnet.

The form of magnet used in medical practice is chiefly the horseshoe, and, to obtain sufficient power, several permanent magnets are clamped together. The magnetic pole with which the effect is intended to be produced may be gently stroked along the course of the nerve in cases of neuralgia, or the magnet may be fastened on the part by suitable straps. The duration of the application will be determined by the effects. In some cases the result is little short of magical; in others, apparently of the same character, no effect follows.