During the sixteenth and seventeenth centuries the application of magnets was a favorite treatment for a great many diseases. Especially were they useful in the treatment of muscular pains and aches and the chronic diseases which so disturbed men's minds. Many of the joint troubles of the aged, the muscular pains and aches that develop from the wrong use of muscles, and the vague internal discomforts which often disturb men so seriously, were cured by the application of magnets. Perkins' success with his tractors shows how much can be accomplished in this way. ELECTROTHERAPY The great development of pseudo-science in medicine remained for the era following the scientific investigation of electricity. With the discovery of the Leyden jar and its startling spark, a new and marvelous healing agent seemed to be at hand. It is quite amusing to read the accounts of the influence of the spark of the Leyden jar on the well and on the ailing. In my "Catholic Churchmen in Science" (Dolphin Press, Phila., 1909) I summed up the situation. Winckler of Leipzig said that the first time he tried the jar, he found great convulsions by it in his body; it put his blood into great agitation; he was afraid of an ardent fever, and was obliged to use refrigerating medicines. He felt a heaviness in his head as if a stone lay upon it. Twice it gave him a bleeding at the nose. After the second shock his wife could scarcely walk, and, though a week later, her curiosity stronger than her fears, she tried it once more, it caused her to bleed at the nose after taking it only once. Many men were terrified by it, and even serious professors describe entirely imaginary symptoms. The jar was taken around Europe for exhibition purposes, and did more to awaken popular interest than all the publications of the learned with regard to electricity, in all the preceding centuries.