. Electrical world. He established by experiment that every fragment of a lode-stone, however small, is a complete magnet, thus anticipating one ofour fundamental laboratory illustrations of the molecular theory; (d) He recognized that a pole of a magnet may neutralize aweaker one of the same name, and even reverse its polarity; (e) He was the first to pivot a magnetized needle and surroundit with a graduated circle, Figs, i and 2 ;- (f) He determined the position of an object by its magneticbearing as done to-day in compass surveying; and (g) He introduced into his perpetual-motion machine. F
. Electrical world. He established by experiment that every fragment of a lode-stone, however small, is a complete magnet, thus anticipating one ofour fundamental laboratory illustrations of the molecular theory; (d) He recognized that a pole of a magnet may neutralize aweaker one of the same name, and even reverse its polarity; (e) He was the first to pivot a magnetized needle and surroundit with a graduated circle, Figs, i and 2 ;- (f) He determined the position of an object by its magneticbearing as done to-day in compass surveying; and (g) He introduced into his perpetual-motion machine. Fig. 3,the idea of a magnetic motor, a clever idea, indeed, for a thirteenthcentury engineer. This rapid summary will serve to show that the letter of Pere-grinus is one of great interest in physics as well as in navigationand geodesy. For nearly three centuries it lay unnoticed among thelibraries of Europe, but it did not escape Gilbert, who makes fre-quent mention of it in his De Magnctc, 1600; nor the illustrious. FIG. 3.—THE COXTINUOUSLY-MOVING WHEEL, OR MOTOR,OF PEREGRINUS, AFTER GASSER. Jesuit writers, Cabseus, who refers to it in his Philosophia Magnetica,1629, and Kircher, who quotes from it inhis De Arte Magnetica,1641; it was well known to Jean Taisnier, the Belgian plagiarist,who transferred a great part of it verbatim to the pages of his DcNatura Magtictis, 1562, without a word of acknowledgement. Bythis piece of fraud Taisnier acquired considerable celebrity, a factthat goes to show the meritorious character of the work which heunscrupulously copied. This memorable letter is divided into two parts: the first containsten chapters on the general properties of the lodestone; the secondhas but three chapters, and shows how the author proposed to use alodestone for the purpose of producing continuous rotation. There are many manuscript copies of the letter in Europeanlibraries: the Bodleian has six; the Vatican, two; Trinity College,Dublin, one; the Bibliothe
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
