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Peter Peregrinus,also known as Pierre De Maricourt


also known as Pierre de Maricourt ( fl. ca. 1269)


Other than that he was the author of the first extant treatise on the properties and applications of magnets, virtually nothing is known of Peregrinus. Two sources provide what little data we have: (1) his famous letter, or treatise, on the magnet, Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt, Militetn, De Magnete,1 “Letter on the Magnet of Peter Peregrinus of Maricourt to Sygerus of Foucaucourt, Soldier”; and (2) the Opus tertitun of Roger Bacon.

Only one date in Peregrinus’ life is fixed with certainty. At the conclusion of the Epistola, he added “Completed in camp, at the siege of Lucera, in the year of our Lord 1269, eighth day of August2. From this account it would appear that Peregrinus was a member of the army of Charles of Anjou, King of Sicily, who was at that time personally directing an assault on Lucera (a city in Apulia, approximately twelve miles west of Foggia). Given Peregrinus’ apparent interest oin mechanical devices and instruments, Schlund has suggested3 that he may have served in some technical capacity, perhaps as an engineer

Peter may have received the appellation“Peregrinus” in connection with one or more of the assaults on Lucera. Under the control of the Hohenstaufens, Lucera had been besieged three times between 1255 and 1269, when it fell for the last time. The Papacy had declared these assaults against the Hohenstaufens and thier Saracen allies offical crusades.Since during the twelfth and thirteenth centuries the honorific title “peregrinus” could be awarded not only to those who went on pilgrimages to the ponly to those who went on pilgrimages to the Holy Land but also to those who fought in recognized crusades in the Holy Land and elsewhere, Peregrinus may have thus earned it by participating in the siege.4

The manuscripts of the Epistola indicate that Peregrinus’ full name was Petrus de Maharncuria, or Pierre de maricourt signifying that he probably came from the town of Méharicourt in Picardy5. Although there is evidence that Peregrinus was of noble birth,6 the suggestion that he was a theologian is unconvincing7 and the assertion that he was a Franciscan is baseless.8 The lack of biographical data has even prompted an unsuccessful attempt to determine whether Peregrinus might be indentical with one of his better-known thirteenth-century namesakes9

Apart from the little that is revealed by the Epistola itself, further knowledge of Peregrinus as a scientist and investigator of natural phenomena depends heavily on the autheticity of certain statements in Roger Bacon’s Opus tertium and whether in that same treatise Peregrinus is intended in references to a“Master Peter” (Magister Petrus). In chapter 11 of that treatise, which was written during 1267,10 Bacon spoke of the need for good mathematicians and declared that“there are only two perfect mathematicians, Master John of London and Master (Magister) Peter de Maharn-curia, a Picard.”11 Since two of the five manuscripts of the Opus tetrium, including the oldest, carry this satement in the margin, it is possible that it was added by a scribe and subsequently incorporated into the text of other manuscripts,12 It is therefore difficult to give full credence to the claim that Bacon had Peregrinus13 in mind when, a few lines below, he stated “Nor can any one obtain their services [that is, of good mathematicians] unless he be the Pope or another great prince, especially the services of that one who is the best of all of them, of whom I have written in the Opusminus and shall write again in [the proper] place.”14> Since Peregrinus is neither mentioned nor alluded to in the single fragmentary manuscript of the Opus minus15 known thus far, the claim is further eroded. Whoever may have been the author of the statement citing Peregrinus as one of two “perfect mathematicians,” it is of interest that he referred to him as“Magister,” probably signifying that peregrinus had earned a Master of Arts degree, perhaps at the University of Paris.

In chapter 13 of the Opus tertium, Bacon praised a “Magister Petrus” as the only Latin writer to realize that experience rather than argument is the basis of certainly in science.16 Later in the same chapter, following a discussion of burning mirrors, Bacon declared that “I know of only one person who deserves praise in the works of this science.” At this point a marginal notation in one17 of the five manuscripts used in Brewer’s edition of the Opus tertium reads: “Notandum de magistro Petro de Maharne Curia” (“It should be noted that this is about Peter of Macharne Curia”). If the glossator is correct, it becomes highly probable that Peregrinus was intended by the earlier reference to “Magister Petrus,” and Bacon’s laudatory description in the lines that follow must also refer to Peregrinus. Bacon’s descrption would reveal an idealistic and indefatigable scientist:

.…for he does not trouble about discourses or quarrles over words, but follows the works of wisdom and keeps quietly to them. And so, though others strive blinkingly to see, as a bat in the twilight, the light of the sun, he himself contemplates it in its full splendour, on account of which he is a master of experiments (dominus experimentorum) and thus by experience he knows natural, medical, and alchemical things, as well as all things in the heavens and beneath them: indeed he is shamed if any layman, or grandam, or soldier, or country bumpkin knows anything that he himself does not know. Wherefore he has inquired into all operations of metal-founding and the working of gold and silver and other metals, and of all minerals; and he knows all things pertaining to the army and to arms and the chase: and he has examined all that relates to agriculture, the measurement of land, and the works of farmers; and he has also reflected upon the experiments, devices, and incantations of withces and magicians, and likewise the illusions and tricks of all jugglers; so that nothing is hidden from him which he ought to know, and he knows how to reprobate18 all things false and magical. And so without him it is impossible that philosophy could be completed, or be treated usefully or with certainly. But just as he cannot be valued with respect to price, so he does not estimate his own worth. For should he wish to stand well with kings and princes, he would find those who would honour him and enrich him. Or, if he were to show in Paris by his works of wisdom all that he knows, the whole world would follow him: yet because either way he would be hindered from the bulk of his experiments in which he most delights, so he neglects all honour and enrichment, the more since he might, whenever he wished it, attain to riches by his wisdom.19

On the basis of this extraordinary encomium, written in 1267, Bacon is conjectured to have met, or to have come to know about, Peregrinus during the 1260’s. Had Bacon known him earlier it is likely that he would have mentioned him in the Communia mathematica, written in the late 1250’s, in which Robert Grosseteste, Adam March, and John Bandoun are singled out as praiseworthy methematicans.20

Despite the paucity of information about Peregrinus it seems evident that he was greatly, and perhaps primarily, interested in the construction of instruments and devices. According to him the Epistola was to form “part of a treatise in which we shall show how to construct physical instruments.”21 Similar interests are reflected in part 2, chapter 2, of the Epistola, where Peregrinus declares his intention to explain“how iron is held suspended in air by virtue of the stone”22 in the book on the action of mirrors” (in libro de operibus speculorum) which he was writing or planned to write.

Although no such work has yet been found, Bacon, immedialtely following the lengthy passage quoted above and still, presumably, speaking of Peregrinus, stated that “He [that is, Peregrinus] has already labored three years on one burning mirror [set for?] a fixed distance and by the grace of God will soon complete it. Although we have books on the construction of such mirrors, the Latins are ignorant as to how to build them, nor has any among them attempted it.”23 Twice again prasie is the Opus tertium (chaps. 33 and 36)24 lavish praise is heaped upon the constructor of this same burning mirror (or so it seems) and the mirror itself, now mentioned as actually completed. A treatise on the construction of an astrolabe (Nova compositio astrilabii paricilaris),25 in which the year 1261 is mentioned, has been attrbuted to Peregirums adn bears furher withness to hsi overriding interest in the fabrication of instruments

Turning to the magnet or lodestone itself, in part 1, chapter 3,Peregrinus named four characteristics: color (it should resemble polished iron exposed to the tarnishing effect of the air); homogeneity (although a magnet is rarely completely homogeneous, the more homogeneous it is, the more efficiently it performs); weight (a function of homogeneity and density—a heavier magnet is a better magnet); and virtue, or power to attract iron. Althought the north south orientation properties of a magnetic compasses since the eleventh century (and probably earlier) in China and since the twelfth century in the Latin West,26 and although it had been known from antiquity that magnets could attract and repel iron, Peregrinus left the first extant account of magneticc Polarity and methods for determining the poles of a magnet (pt. 1, chap. 4; Peregrinus may also have been the first to apply the term Polus to magnetic pole).27 Just as the celestial sphere has a north and south pole, so also does every magnet.

Scientific Thought . Since the Epistola is the sole authentic work attributed to Peregrinus that has been edited and made generally known, it alone must serve for the present as the basis of any evaluation of his scientific achievement. The Epistola is a brief treatise in two parts; the first, in ten chapters, descriibes the properties and effects of hte lodestone, while teh second, in three chapters, is devoted to the constrution of three instruments utilizing the special properties powers of the magnet.

The scope of the work and the essential prerequisites for conducting an investigation into magnetism are outlined in the first two chapters. Since the Epistola was to constitute part of a larger treatise on the construction of instruments, Peregrinus explicitly confined his attention to the manifest properties of the mangent,leaving aside all consideration of itsoccult powers . An investigator into the properties of magnetism must not only be knowledgeable about nature and the celestial motions, but also be clever in the use of his hands

A celestial analogy aided Peregrinus in his description of the first of two methods for locating the poles of a magnet. Since the meridian circles of the celestial sphere converge and meet at the poles, the lines drawn on a spherical magnet (called a terrella by William Gillbert28 but perhaps first shaped and used by Peregrinus) will similarly meet at the poles when the investigator adheres to the folowing procedure:

Let a needle or elogated piece of iron, slender like a needle, be placed on the stone, and a line be drawn along the length of iron dividing the stonein the middle. Then let the needle or iron be placed in another position on the stone and mark the stone the with a line in a simialr manner according to that position.29

All the lines drawn in this fashion will converge in the two opposite points or poles. The poles may also be found by nothing at what point on the spherical magnet a needle or piece of iron clings with the greatest force. To render this method more precise, Peregrinus recommended that a small, oblong needle, or piece of iron, of approximately two finger nails in length, be located on or near the poles until it lies perpendicular to the stone (that is, stands upright). The marks representing these points should lie diametrically opposite. The two methods described here were also employed by Gilbert.30

In distinguishing north and south poles (pt. 1, chap. 5), Peregrinus presented a qualitative description of the fundamental law of magnetic polarity. If a lodestone is laid in a plate or cup, which in turn is placed in a vessel filled with water so that“the stone may be like a sailor in a ship”31 that is, free to turn in any direction without colliding into the sides of the vessel-then the north pole of the lodestone (polus septentrinalis lapidis) will face toward the north celestial pole and the south pole of the stone will face to the south celestial pole. Peregrinus observed that whenever the lodestone is forcibly turned away from its north-south orientation, it will always return to that orientation upon removal of the constraint.

The effect that a hand-held magnet will have upon a floating magnet serves as a paradigm for the general effect that one magnet has upon another (pt. 1, chap. 6). If the north pole of a hand-held magnet is brought in close proximity to the south pole of a floating magnet, the latter will seek to adhere to the former, an effect that will be repeated when the south pole of the hand-held magnet is brought near the north pole of the floating magnet. After formalizing this behavior in a general rule, Peregrinus observed that when the like poles of these magnets are brought close together, “the stone which you hold in your hand will appear to flee the floating stone.”32 To explain attraction and repulsion between the poles of magnets, Peregrinus resorted (pt. 1, cap. 9) to the agent-patient relationship so popular in medieval natural philosophy. He observed that if a magnet is broken in two each part will function as a magnet with north and south poles. If the opposite poles of the parts are then brought together, they will seek to unite and rejoin into a single magnet, since “an active agent strives not only to join its patient to itself but to unite with it, so that out of the agent and the patient there may be made one.”33 Indeed, if the two parts were cemented at the point of contact, the opposite poles would become unified and the resulting magnet would have a north and south pole and be identical in every way with the original magnet. The union of agent and patient, which involves an attraction and union of opposite poles, is accounted for by a “likeness” or “similitude” (similitudo) between them. Peregrinus does not explain how a “simulitude” between opposite poles is to be understood. John of St. Amand (fl. 1261–1298), a medical commentator and seeming contemporary of Peregrinus, likewise sought to account for the attraction between magnets and between a magnet and iron by saying that“t [that is, the magnet] does it by multiplying its like (similitudo) and, without any evaporation, exciting the active power which exists incomplete in iron, which is born to be completed by the form of the magnet, nay is moved towards it.”34

On the question of which of two mutually attracting magnets is the agent is the agent and which the patient Peregrinus provided no answer. Peregrinus provided no answer. Persumably, if one magnet were assumed to be stationary (say, held in the hand) and the other free to move, it would be plausible to expect Peregrinus to designate the former as agent and the latter as patient. Otherwise the choice seems wholly arbitrary. Should the two north (or south) poles be brought into proximity, the two magnets could not be reunited into a single magnet, since the “identity or similitude of the parts would not be conserved”.35 The single magnet formed from the joining of like poles would possess two north (or south) poles and would differ in species from the original magnet, which possessed two opposite poles.

The ability of a magnet to orient itself with the celestial poles in a north-south direction is transmissible to iron upon contact (pt. 1, chap. 7). Let a magnetized iron needle (whether by“iron needle” Peregrinus meant iron or steel is left unspecified; if iron, the needle would have required repeated remagnetization)36 be placed upon a piece of wood or straw that floats upon water. The end of the needle that had been touched by the region around the north pole of the magnet will turn toward the southern part of the heavens; and, conversely, the end touched by the area around the south pole of the magnet will orient itself toward the north celestial pole (but not the pole star). Since the magnetized needle takes on the polar properties of a magnet, it will behave like a magnet. Consequently, the south pole of the needle will be attracted to the north pole of the magnet and repelled by its north pole (pt. 1, chap. 8). The polarity of a magnetized needle is reversible, however, when, as Peregrinus (and also John of St. Amand)37 observed, similar poles of a magnet and magnetized needle are brought into contact. When the north pole of a magnet is made to touch the north pole of a needle, it converts the latter to a south pole. “And the cause of this,” Peregrinus explained, “is the impression of the last agent, confounding and changing the virtue of the first, “38 Given the agent-patient relationship discussed in part 1, chapter 9, Peregrinus would undoubtedly have accounted for this as the striving of an agent, the magnet, to unite with its patient, the iron needle. To achieve this objection the agnet transforms the patient by altering its north pole to a south pole

Although knowledge of magnetic declination (apparently already known in China in the eleventh century40) might have dissuaded Peregrinus from his opinion, there was reasonable evidence in its favor. Peregrinus was convinced that the poles of a magnet orient themselves in the meridian and that all meridians converge at the celestial poles; he was also aware that Polaris, the pole star, does not rest at the celestial north pole, but revolves around it— fact virtually unknown to astronomers or seamen, which Columbus discovered for himself.41 From this knowledge Peregrinus concluded that the poles of a magnet, or magnetized needle, always point directly to the celestial poles rather than to the pole star, as commonly believed.42 From this conclusion it was an easy and perhaps irresistible inference that the poles of a magnet received their power to attract and repel directly from the celestial poles. Indeed, Peregrinus thought that every part of a spherical magnet received its power from the corresponding part of the celestial sphere.43

It was almost inevitable that Peregrinus should have inquired about the source of magnetic force (pt. 1, chap. 10). First, he disposed of the popular view that mines of magnetic stone in northern regions were the cause of the north-south orientation of a magnet. To support his position, Peregrinus stated that (1) magnetic stone is found in many parts of the world; (2) the polar regions are uninhabitable and thus could not be the source of magnetic stone; and (3) a magnet, or magnetized iron, orients to the south as well as the north. In rightly rejecting this notion, however, Peregrinus overlooked the fruitful concept, developed later by Gilbert, that the earth itself is a large spherical magnet. Instead, Peregrinus looked to the heavens in the belief that the poles of a magnet receive their virtue from the celestial poles.39

As a test for this claim, he suggested the construction of a spherical magnet with fixed pivots at its poles, which would leave the magnet free to rotate. The sphere should be positioned on the meridian circle “so that it moved in the manner of armillaries in such a way that the elevation and depression of its poles may correspond with the elevation and depression of the poles of the heavens in the region where you may be.”44 If these instructions are followed faithfully, the spherical magnet, receiving magnetic virtue from every part of the celestial sphere, should commence to turn on its axis round the pivots,45 thus simulating the daily celestial motion and functioning as a perfect clock. Although Peregrinus did not claim to have constructed such a perpetual motion machine, there is the hint that an abortive attempt was made, for he stated that failure of the sphere to perform as described could only be attributed to lack of skill in the contriver rather than deficiency in the theory, which he judged wholly sound. Peregrinus thus insulated his theory from the practical consequences that he himself deduced from it. Both Gilbert, who referred to this passage and mentioned Peregrinus by name,46 and Galileo47 rejected such claims.

Magnetic power as a source of perpetual motion is taken up again at the conclusion of the Epistola (pt. 2, chap. 3), where Peregrinus described construction of a continually moving toothed wheel powered by an oval magnet. The latter is so positioned that each tooth of the wheel will, in turn, be attracted to the north pole of the magnet. Under the influence of the attraction, the tooth acquires sufficient momentum to move beyond the north pole and into the vicinity of the south pole ,by which it is repelled toward the north pole. As each tooth is alternately attracted and repelled, the wheel maintains a perpetual motion. Thus Peregrinus joined Villard de Honnecourt (fl. 1225–1250)48 in proposing perpetual motion wheels in defiance of medieval Scholastic theory, which generally denied the possibility of inexhaustible forces in nature.

If Peregrinus’ attempt to apply magnetic force to perpetual motion was misconceived, his use of it in the improvement of the compass was surely not. He described two compasses, one wet and one dry. The first (pt. 2, chap. 1), a floating compass, represents a considerable improvement over those that had been in use; an oval magnet is encapsulated in a wooden case and floated on water in a large rounded vessel. The rim of the vessel is divided into four quadrants according to the cardinal points of the compass. Each quadrant is then subdivided into ninety equal parts. A rule with sighting pins, positioned perpendicularly at each end, is placed on the encapsulated magnet. This rule extends to diametrically opposed points on the graduated rim. With this instrument, perhaps the first mariner ’s compass with divisions, not only could the direction of a ship be determined, but also the azimuth of the sun, moon, and stars. Although the Chinese used magnetic compasses with geomantic divisions centuries before Peregrinus,49 it is not clear whether they used them in the mariner’s compass, of which clear mention is made in the eleventh century.50

The second compass (pt. 2, chap. 2), dry and pivoted, was deemed by Peregrinus an improvement over the floating compass. A vessel in the shape of a jar (which may be made from any solid material, preferably transparent) is constructed with a transparent lid of glass of crystal on which are market the cardinal points. After subdividing each quadrant into ninety parts or degrees, a movable rule with perpendicular sights is fastened to the top of the lid. An axis of brass or silver is positioned at the center of the vessel between the bottom side of the lid and the bottom of the vessel. In the center of the axis, and at right angles to it, two needles–one of iron, the other of brass or silver–are inserted perpendicular to each other. Upon magnetizing the iron needle, the vessel, with its lid, is turned until the north-south points of the lid are aligned with the magnetized needle (as an obvious consequence, the silver or brass needle becomes aligned in an east-west direction). Azimuthal readings of the sun and stars may now be taken by rotating the movable rule on the lid. Peregrinus appears to have been the first to describe such a compass.51

The Epistolaranks as one of the most impressive scientific treatises of the Middle Ages. Although much of what Peregrinus included may have been known and expressed earlier in a vague and incomplete manner, the Epistola was the first extant treatise devoted exclusively to magnetism. Not only did Peregrinus bring together virtually all the relevant, contemporary knowledge on magnetism, but he obviously added to it and, of the greatest importance, organized the whole into a science of magnetism. He formulated rules for the enabled him to enunciate rules for attraction and repulsion, all of which would today form the basis of an introductory lesson on magnetism.52 As the two magnetic compasses and perpetual motion devices for clock and wheel testify, Peregrinus was also seriously concerned with the practical application of magnetic force. The subsequent influence of his treatise was considerable. The existence of at least thirty-one manuscript versions of it bears witness to its popularity during the Middle Ages. Of greater significance, however, was its eventual impact on Gilbert, who, in his famous De Magnate (1600), not only upon the Epistola to build upon and add to the solid empirical rules on magnetic polarity and induction formulated by Peregrinus more than three centuries earlier.


1. I have cited the title as given in Bertelli’s ed., Bullettino, I Rome, 1868), 70. For variant titles, see Bertelli, ibid., 4-7; E Schlund,“Petrus Peregrinus von Maricourt,” in Archivum Franciscanum historicum,, 5 (1912), 22– and S.P.Thompson,“Petrus Peregrinus de maricourt,” in Proceedings of the British Academy, 2 (1905-1906), 400-407.

2. From the trans, of the Epistola by H. D.Harradon,“Some Early Contributions to the History of Geomagnetism—I,” 17. Although the date 1269 is recorded in only three of thirty-one known MSS, it appears in what may be the oldest of them (see Schlund,“Petrus Peregrinus,” in Archivum Franciscunum histroricum, 4 [1911], 450, and 5 [1912], 23.

3. Schlund, ibid., 4 455.,

4. For details on the crusades against Lucera and the significance of the term“peregrinus,” see Schlund, ibid., 450-455.

5. Schlund, ibid., 449.

6. Schlund, ibid., 451; based on a Picard family“de Maricourt” listed ion the Dictionnaire de la Noblesse by De la Chenaux Desbois.

7. F. Picavet, Essais sur l’historie generale et comparee des theologies et des philosophies medievales, 240-242, 252.

8.. Stewart Easton, Roger Bacon and His Search for a Universal Science (Oxford, 1952), 120–121.

9. Schlund,“Petrus Peregrinus,” in Archivum Franciscunum Historicum, 4 441–448.

10. Bacon himself mentions the year. See 277, 278 of J.S.Brewer’s ed. of Bacon’s Opus tertium, Opus minus, and Compendium studi philosophie in Fr. Rogeri Bacon Opera quaedam hactenus inedita (Rerum Britannicarum Medii Aevi, no. 15; London, 1859).

11. Brewer, ibid., lxxv and 35.

12. See Schlund, “Petrus Pererinus,” in Archivum Franciscanum histroricm, 4 445–446.

13. Brewer, Fr. Rogeri bacon, xxxvii.

14. My translation from Brewer, ibid., 35. Brewer gives two variant translation on xxxvii and lxxv.

15. Brewer, ibid., Even if an alleged marginal gloss in the Opus minus mentioning a “Master Peter” is a correct reading-and this is dubious-ther is no good reason to assume that Peregrinus is the“Peter” intended (see Schlund,“Petrus Peregrinus,” in Archivum Franciscanum historicum, 4 446-447).

16. Brewer, ibid., 43.

17. Oxford, Bodleian, “e Musaeo” 155–3705; for the Latin text, see Brewer, ibid., 46.

18. At this point, “Petrus de Maharne Curia” appears as a marginal gloss in British Museum, Cotton MSS, Tiberius C. V.

19. Thompson’s trans., 380. I have slightly altered the trans., which was made from Brewer’s ed., 46–47.

20. Easton, Roger Bacon, 88.

21. Pt. 1, chap. 1, as translated by H. D. Harradon in Terrestrial Magnetism and Atmospheric Electricity, 48 (1943), 6.

22. Harradon, ibid., 16. On the claims to suspend iron in air by magnets, see Dorothy Wyckoff’s trans., Albertus Magnus Book of Minerals (Oxford, 1967), 148 and Bertelli, Bullettinio 1, 87, n 6.

23. My trans, from Brewer’s ed., 47; see also Thompson’s trans., 379.

24. Brewer, Fr. Roger Bacon, 112–116; see also F. Picavet, Essais sur l’jistorie generale et comparee des theologies et des philosophies medievales, 247, 252.

25. See Bertelli, Bullettino 1, 5, and bibliography, below.

26. Joseph Needham, Science and Civillistion in China, iv (Cambridge, 1961), pt. 1, 246, 249-250, and 274.

27. Schlund, “Petrus Peregrinus,” in Archivum Franciscanum historicum, 4 636, n. 5.

28.De Magnete, bk. I, chap. 3, in Thompson’s English trans., On the Magnet, 2nd ed. (New York, 1958; 1st ed., London, 1900), 13.

29. Harrdon trans., 7.

30.De Magnete, bk. I. chap. 3 (1314 of Thompson’s trans.). Gilbert employed a third method using a versorium, that is, “a piece of iron touched with a loadstone, and placed upon a needle or point firmly fixed on it foot so as to turn freely about” (ibid.)

31. Harradon trans., 8.


33.Ibid., 10. On medieval explanations of the causes of magnetic attraction, see W. James King,“The Natural Philosophy of William Gilbert and His Predecessors,” in Contributions From the Museum of History and Technology, Smithsonian Instituion Bulletin 218 (Washington, D.C., 1959), 125–129, and Harry A. Wolfson, Crescas Critique of Aristotle (Cambridge, Mass., 1929), 90–92.

34. See Lynn Thorndike ,“John of St. Amand on the Magnet,” in Isis, 36 (1945), 156.

35. Harradon trans., 10

36. E. Gerland, Geschichte der Physik (Berlin, 1913), 213.

37. Thorndike ,“John of St. Amand,” 157.

38. Harrdon trans., 9.

39. Gilbert (De Magnete, bk. III, ch. 1; Thompson’s trans., 116), citing Peregrinus by name, emphatically rejects this explanation.

40. Needham, Science and Civilisation in China, IV, pt. 1, 250.

41. See Samuel Eliot Morison, Admiral of the Ocean Sea, A Life of Christopher Columbs, 2 vols. (Boston, 1942), I. 271.

42. See Duane H.D.Roller, The “De Magnete” of William Gilbert, 36, 39.

43. A similar view was expressed by John of St. Amand; see thorndike, “John of St. Amand,” 156-157.

44. Harradon trans., 11-12.

45. Without mention of either Peregrinus or the title of the treatise, Nicole Oresme, in bk. II, question 3, of hisQuestions super De Celo makes a probable reference to this device. See Claudia Kren, ’ of Nicole Oresme” (Ph.D.Diss., University of Wisconsin, 1965), 474-476.

46.De Magnete, bk. VI, chap, 4; Thompson trans., 223.

47. Stillman Drake, trans., Dialogue Concerning the Two Chief World Systems (Berkeley, Calif., 1962), 413–414.

48. See Theodore Bowie, The Sketchbook of Villard de Honnecourt (Bloomington, Ind., 1959), 134.

49. Needham, Science and Civilisation in China, IV, pt. 1, 262-263, 296–297.

50.ibid., 279–280.

51. Thompson, 388. The Chinese did not learn of the dry, pivoted compass until the sixteenth century (Needham, Science and Civilisation in China, IV, pt. 1, 290).

52. E. J. Dijksterhuis, The Mechanization of the World Picture (Oxford, 1961), 153.


I.Original Works. The most complete list of MSS of the Epistola has been compiled by Erhard Schlund, O.F.M., in “Petrus Peregrinus von Maricourt, sein Leben und seine Schriften (ein Beitrag zur Roger Baco-Forschung),” in Archivum Franciscanum historicum, 5 (1912), 22–35. Of the 31 extant MSS described, 29 are Latin (for easier identification, the opening and closing lines [that is, incipits and explicits] are often supplied) and two, located in Vienna, represent two versions of a single Italian trans, made during the Middle Ages or Renaissance. In addition, five Latin MSS that may once have existed but their fate of which are unknown are also briefly cited and discussed. Another list of MSS, not quite as complete as Schlund’s but including an English trans., possibly of the late sixteenth or early seventeenth century (in Gonville and Caius College, Cambridge), has been published by Silvanus P. Thompson, F.R.S., “Petrus Peregrinus de Maricourt and his E[pistola De Magnete,” in Proceedings of the British Academy, 2 (1905–1906), 400–404. Included are MSS owned by Thompson as well as five MSS the previous existence of which is plausibly conjectured. In the same article (404–408), Thompson presents the most comprehensive list yet produced of the printed eds. and trans, of the Epistola (11 partial and complete versions in all are cited; a useful but less extensive list appears in Schlund’s article on 36–40; the original basis of both lists was probably furnished by Baldassare Boncompagni, “Intorno alle edizional della Epistola De Magnete di Pietro Pergrino de maricourt,” in Bullettino di bibliografia e di storia delle scienze mathematiche e fisiche, IV [Rome, 1871], 332–339).

The first published ed. was that of Achilles P. Gasser, Petri Peregrini Maricurtensis De magnete seu Rota perpetui motus libellus... (Augsburg, 1558), which was followed by a few inadequate and truncated versions. Not until 1868 did the first critical text appear. Working from 7 MSS and the 1558 ed., Timoteo Bertelli, a Barnabite monk, published a new ed. of the Epistola in “Sulla Epistola di Pietro Pereggrino di Maricourt e sopra alcuni trovati e teoric magnetiche del secolo XII,” in Bullettino di bibliografia e di storia delle scienze matematiche e fisiche, I (Rome,1868), 70–89. A few years later, in an article entitled “Intorno a due Codici Vaticani della Epistola De Magnete de Pietro Peregrino di Maricourt,” in Bullettino, IV (Rome, 1971), 303–331, Bertelli listed additional variant readings (see especially, 315–319) to his ed. of 1868. Using Bertelli’s ed. and incorporating some of the later variants, G. Hellmann published another ed. of the Epistola in his Rara Magnetica, Neudrucke von Schriften und Kartebn Über Meterologie und Erdmagnetismus (Berlin, 1898), no. 10. By collating at least nine additional MSS (seven from Oxford) with printed eds., especially Bertelli’s , Silvanus P.Thompson, on 390–398 of his article cited above, subsequently published a large number of additional variants, cuing them to the page and line numbers of Bertelli’s ’868 ed. Thus despite five printed Latin eds., as well as a plagiarized version by Joannes Taisnier (1562), a facs. repr. by Bernard Quaritch (1900), and an ed. and English trans. promised by Charles Sanders Peirce (Prospectus of an Edition of 300 Numbered Copies [150 for America] of the Earliest Work of Experimental Science; The Epistle of Pierre Pelerin de Maricourt to Sygur de Foucaucourt, Soldier, On the Lodestone [New York, 1892], 16 pp., of which pp. 12–13 contain a sample Latin text based on Bibliotheque Nationale, fonds Latin, 7378A; see Thompson’s article, pp.406–407 for a full description and Collected Papers of Charles Sanders Peirce, VII, VIII, Arthur W. Burks, ed. [Cambridge, Mass., 1966], 280–282, for a lengthy quotation from 1–6 of the Prospectus, which Burks dates ca. 1893), there is as yet no single definitive Latin ed. based on all or most of the MSS.

Leaving aside two early printed English trans. of 1579 (?) and 1800 (see Thompson, 405), there now exist three major modern English trans. (1) Silvanus P. Thompson, Epistle of Petrus Peregrinus of Maricourt, to Sygerus of Foucaucourt, Soldier, Concerning the Magnet (London, 1902), based upon the eds. of Gasser, Bertelli, and Hellmann; (2) The Letter of Petrus Peregrinus On the Magnet, A. D. 1269, translated by Brother Arnold [Joseph Charles Mertens] with introductory notice by Brother Potamian [M. F. O’Reilly] (New York, 1904), made from the Gasser ed.; and (3) H. D. Harradon, “Some Early Contributions to the History of Geomagnetism—I,” in Terrestrial Magnetism and Atmospheric Electricity (now the Journal of Geophysical Research), 48 (1943), 3–17. The title of the trans., which actually appears on 6–17, is“ The Letter of Peter Peregrinus de Maricourt to Sygerus de Foucaucourt, Soldier, Concerning the Magnet.” Although Harradon makes no mention of the ed., or eds., on which his trans. was based, one may conjecture that Hellmann’s ed. was used. Included in Harradon’s trans, is a prologue consisting solely of chapter titles, which Thompson (384 of the article cited above) believes is a scribal interpolation compiled from the original chapter headings that precede each chapter.

An as yet unexamined and unpublished work on the construction of an astrolabe is assigned to Peregrinus in the title of a treatise in Latin MS codex Vatican Palatine 1392, which reads: Petri Peregrini Nova Compositio Astrolabii Particularis (Peter Peregrinus’ New Composition [or Construction] of a Special Astrolabe); no folio numbers are given by T. Bertelli, who mentions the MS in his article “Sopra Pietro Peregrino di Maricourt e la sua Epistola De Magnete”, in Bullettino, I (Rome, 1868), 5. Since reference is made to certain astronomical tables completed by Campanus of Novara in 1261, the treatise was probably written after that date (see Bertelli, ibid., 5, n. 1). A second MS is reported (without folio numbers) in the Library of Genoa (“à =small a, grave accent la Bibl. de Genes “ by J. G. Houzeau and A. Lancaster, General Bibliography of Astronomy to the Year 1880, I, pts. 1 and 2, new ed. with intro. and author index by D. W. Dewhirst (London, 1954), 640, col. 1, nr. 3197. Some suspicion is cast on this reference, however, since the authors cite the very page in Bertelli’s memoir where the Vatican MS is listed. Whether they intended to identify a second manuscript“à la Bibl. de Genes” (that is, Genoa) or merely to report the existence of the Vatican MS, which erroneously became a Genoa MS, is unclear. A possible third MS appears among Schlund’s list of MSS of Peregrinus’ Epistola “ Petrus Peregrinus von Maricourt,” 5 [1921], 32, nr. 27). On fol. 20r-22v and 25v-36r of Latin codex Ö sterreichische Nationalbibliiothek, Vienna, 5184 (sixteenth century), treatises, or parts of treatises, appear, titled respectively, Tractatus De Compositione Instrumenti Horarum Diei et Noctis (Treatise On the Construction of an Instrument for [Determinig] the Hours of the Day and the Night) and Tractatus De Compositione Astrolabii (Treatise On the Construction of an Astrolabe). Schlund conjecture that both were parts of the Epistola but the second might well be all or part of the Nova Compositio Astrolabii Particularis.

II.Secondary Literature. The most extensive study of Peregrinus and his Epistola consists of two memoirs by Timoteo Bertelli in Bullettino di bibliografia e di storia delle scienze matemathiche e fisiche, I (Rome, 1868). The first (“ memoria prima “) G“Sopra Pietro Peregrino di Maricourt e la sua Epistola De Magnete”, 1–32, is concerened with Peregrinus’ life, MSS of the Epistola, and contemporary and later authors, down to 1868, who spoke of Peregrinus, used his work, or edited and translated his treatise. The second memoir (“memoira seconda”) ,“Sulla Epistola di Pietro Peregrino di Maricourt e sopra alcuni trovati e teorie magnetiche del secolo XIII,” is in three parts. Part 1, 65–89, includes the Latin ed. of the Epistola and a description of the MSS used; part 2, 90–99, 101–139, considers other medieval authors who discussed magnetism; and part 3, 319–420, further analyzes the content of the Epistola and traces its subsequent influence. A careful reexamination and evaluation of the life and works of Peregrinus, as well as a summary of the contents of the Epistola and an attempt to place Peregrinus in the context of scholastic thought, was published by Erhard Schlund, O. F. M., in “Petrus Peregrinus von Maricourt sein Leben und seine Schriften (ein Beitrag zur Roger Baco-Forschung)”, in Archivam Franciscanum historicum, 4 (1911), 436–455, 633–643. Peregrinus’ life and Epistola are sketchily summarized by Silvanus P. Thompson, “Petrus Peregrinus de Maricourt and his Epistola de Magnet,” in Proceedings of the British Academy, 2 (1905–1906), 377–390 (the lists of variants, MSS, eds., and trans. of the Epistola mentioned above, follow on 390–408; see also Thompson’s Peregrinus and his Epistola [London, 1907]). For an examination of Roger Bacon’s alleged remarks about Peregrinus, and an attempt to demonstrate that Peregrinus was a theologian, see Francois Picavet, Essais sur l’histoire generale et comparee des theologies et des philosophies medivales (Paris, 1913), chap. 11 (“ Le maitre des experiences, Pierre de Maricourt, l’exegete et le theologien vantes par Roger Bacon”), 233–254.

Among numerous summaries of the Epistola, see Park Benjamin, The Intellectual Rise of Electricity (London, 1895); Jean Daujat, Origines et formation de la théorie des phénomenes électriques et magnétiques, I (Paris, 1945); Paul Fleury Mottelay, Bibliographical History of Electricity and Magnetism (London, 1922), 45-54 (bibliography on 54); Duane H. D. Roller, The“De Magnet” of William Gilbert (Amsterdam, 1959), 39–42 (see bibliography, 186–190); and Geroge Sarton, Introduction to the History of Science, II, pt. 2 (Baltimore, 1927–1948), 1030–1032, with bibliography. On the specific problem of declination, see Heinrich Winter, “Petrus Peregrinus von Maricourt und die magnestische Missweisung,” in Forschungen und Fortschritte, 11 (1935), 304-306.

Edward Grant

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