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Petrus Peregrinus de Maricourt (Latin), Pierre Pelerin de Maricourt (French), or Peter Peregrinus of Maricourt〔Edward Grant, “Peter Peregrinus,” ''Dictionary of Scientific Biography'' (New York: Scribners, 1975), 10: 532. Ron B. Thomson, “Peter Peregrinus,” ''Medieval Science, Technology and Medicine. An Encyclopedia'', ed. Thomas Glick et al. (New York and London: Routledge, 2005), pp. 388-389.〕 (fl. 1269), was a 13th-century French scholar who conducted experiments on magnetism and wrote the first extant treatise describing the properties of magnets. His work is particularly noted for containing the earliest detailed discussion of freely pivoting compass needles, a fundamental component of the dry compass soon to appear in medieval navigation.〔E. G. R. Taylor: “The South-Pointing Needle”, in: ''Imago Mundi'', Vol. 8. (1951), pp. 1-7〕〔Barbara M. Kreutz, “Mediterranean Contributions to the Medieval Mariner's Compass,” ''Technology and Culture'', Vol. 14, No. 3. (Jul., 1973), p. 371〕〔Frederic C. Lane, “The Economic Meaning of the Invention of the Compass,” ''The American Historical Review'', Vol. 68, No. 3. (Apr., 1963), p. 615f.〕 He also wrote a treatise on the construction and use of a universal astrolabe. Peregrinus’ text on the magnet is entitled in many of the manuscripts of it ''Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt, militem, de magnete'' ("Letter of Peter Peregrinus of Maricourt to Sygerus of Foucaucourt, Soldier, on the Magnet") but it is more commonly known by its short title, ''Epistola de magnete'' ("Letter on the Magnet"). The letter is addressed to an otherwise unknown Picard countryman named Sygerus (Sigerus, Ysaerus) of Foucaucourt, possibly a friend and neighbor of the author; Foucaucourt borders on the home area of Peregrinus around Maricourt, in the present-day ''department'' of the Somme, near Péronne. In only one of the 39 surviving manuscript copies the letter also bears the closing legend ''Actum in castris in obsidione Luceriæ anno domini 1269º 8º die augusti'' ("Done in camp during the siege of Lucera, August 8, 1269"), which might indicate that Peregrinus was in the army of Charles, duke of Anjou and king of Sicily, who in 1269 laid siege to the city of Lucera. However, given that only one manuscript attests this, the evidence is weak.〔See Sturlese in Petrus Peregrinus de Maricourt, ''Opera'' (Pisa, 1995), pp. 16 and 89.〕 There is no indication of why Peter received the sobriquet ''Peregrinus'' (or "pilgrim"), but it suggests that he may have been either a pilgrim at one point or a crusader; and the attack on Lucera of 1269 had been sanctioned as a ''crusade'' by the Pope. So Petrus Peregrinus may have served in that army. "You must realize, dearest friend," Peregrinus writes, "that while the investigator in this subject must understand nature and not be ignorant of the celestial motions, he must also be very diligent in the use of his own hands, so that through the operation of this stone he may show wonderful effects." 〔Jean Gimpel, ''The Medieval Machine: The Industrial Revolution of the Middle Ages'' (New York, Penguin, 1976), 194-5.〕 ==The content of the ''Epistola de magnete''== In his letter of 1269,〔''The letter of Petrus Peregrinus on the magnet, A.D. 1269'' Translated by Brother Arnold (New York, McGraw Publishing, 1904) ((online ))〕 Peregrinus explains how to identify the poles of the compasses. He also describes the laws of magnetic attraction and repulsion. The letters also contain a description of an experiment with a repaired magnet, as well as a number of compasses, one of which "you will be able to direct your steps to cities and islands and to any place whatever in the world." Indeed, the increasing perfection of magnetic compasses during the thirteenth century allowed navigators such as Vandino and Ugolino Vivaldi to strike out on voyages to unknown lands. ; The ''Epistola de magnete'' is divided into two parts. ''Part One'' (10 chapters): This is a section that serves as a model of inductive reasoning based on definite experiences, and setting forth the fundamental laws of magnetism. He did not discover these laws, but presented them in logical order. Part One discusses the physical (but not the occult) properties of the lodestone and provides the first extant written account of the polarity of magnets. He was thus the first to use the word “pole” in this context. He also provides methods for determining the north and south poles of a magnet. He also describes the effects magnets have upon one another, showing that like poles repel each other and unlike poles attract each other. He also treats the attraction of iron by lodestones, the magnetization of iron by lodestones, and the ability to reverse the polarity in such an induced magnet. Peregrinus attributed the Earth's magnetism to the action of celestial poles, rather than to the terrestrial poles of the planet itself.〔Anne Locker, ''Peter the Pilgrim'', IET Communications Engineer, August/September 2006, UK ISSN 1479-8352〕 ''Part Two'' (three chapters): This section describes three devices that utilize the properties of magnets. He treats the practical applications of magnets, describing the “wet” floating compass as an instrument in common use, and proposing a new “dry” pivoted compass in some detail. He also attempts to prove that with the help of magnets it is possible to realize perpetual motion (see History of perpetual motion machines). His device is a toothed wheel which passes near a lodestone so that the teeth are alternately attracted by one pole and repelled by the other. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Petrus Peregrinus de Maricourt」の詳細全文を読む スポンサード リンク
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