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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..19fec70 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #50524 (https://www.gutenberg.org/ebooks/50524) diff --git a/old/50524-0.txt b/old/50524-0.txt deleted file mode 100644 index 5d609ac..0000000 --- a/old/50524-0.txt +++ /dev/null @@ -1,1328 +0,0 @@ -The Project Gutenberg EBook of The Letter of Petrus Peregrinus on the -Magnet, A.D. 1269, by Petrus Peregrinus - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The Letter of Petrus Peregrinus on the Magnet, A.D. 1269 - -Author: Petrus Peregrinus - -Translator: Brother Arnold - -Release Date: November 21, 2015 [EBook #50524] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK LETTER OF PETRUS PEREGRINUS ON MAGNET *** - - - - -Produced by deaurider, Stephen Hutcheson, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - - - - - THE LETTER OF - PETRUS - PEREGRINUS - ON THE MAGNET, A.D. 1269 - - - TRANSLATED BY - BROTHER ARNOLD, M.Sc. - PRINCIPAL OF LA SALLE INSTITUTE, TROY - WITH - INTRODUCTORY NOTICE - BY - BROTHER POTAMIAN, D.Sc. - PROFESSOR OF PHYSICS IN MANHATTAN - COLLEGE, NEW YORK - - - NEW YORK - McGRAW PUBLISHING COMPANY - MCMIV - - Copyright, 1904, by - McGraw Publishing Company - - - - - INTRODUCTORY - - -The magnetic lore of classic antiquity was scanty indeed, being limited -to the attraction which the lodestone manifests for iron. Lucretius -(99-55 B. C.), however, in his poetical dissertation on the magnet, -contained in _De Rerum Natura_, Book VI.[1] recognizes magnetic -repulsion, magnetic induction, and to some extent the magnetic field -with its lines of force, for in verse 1040 he writes: - - Oft from the magnet, too, the steel recedes, - Repelled by turns and re-attracted close. - -And in verse 1085: - - Its viewless, potent virtues men surprise; - Its strange effects, they view with wond’ring eyes - When without aid of hinges, links or springs - A pendant chain we hold of steely rings - Dropt from the stone—the stone the binding source— - Ring cleaves to ring and owns magnetic force: - Those held above, the ones below maintain, - Circle ’neath circle downward draws in vain - Whilst free in air disports the oscillating chain. - -The poet Claudian (365-408 A. D.) wrote a short idyll on the attractive -virtue of the lodestone and its symbolism; St. Augustine (354-430), in -his work _De Civitate Dei_, records the fact that a lodestone, held -under a silver plate, draws after it a scrap of iron lying on the plate. -Abbot Neckam, the Augustinian (1157-1217), distinguishes between the -properties of the two ends of the lodestone, and gives in his _De -Utensilibus_, what is perhaps the earliest reference to the mariner’s -compass that we have. Albertus Magnus, the Dominican (1193-1280), in his -treatise, _De Mineralibus_, enumerates different kinds of natural -magnets and states some of the properties commonly attributed to them; -the minstrel, Guyot de Provins, in a famous satirical poem, written -about 1208, refers to the directive quality of the lodestone and its use -in navigation, as do also Cardinal de Vitry in his _Historia Orientalis_ -(1215-1220); Brunetto Latini, poet, orator and philosopher, in his -_Trésor des Sciences_, a veritable library, written in Paris in 1260; -Raymond Lully, the Enlightened Doctor, in his treatise, _De -Contemplatione_, begun in 1272, and Guido Guinicelli, the poet-priest of -Bologna, who died in 1276. - -The authors of these learned works were too busy with the pen to find -time to devote to the close and prolonged study of natural phenomena -necessary for fruitful discovery, and so had to content themselves with -recording and discussing in their tomes the scientific knowledge of -their age without making any notable additions to it. - -But this was not the case with such contemporaries of theirs as Roger -Bacon, the Franciscan, and his Gallic friend, Pierre de Maricourt, -commonly called Petrus Peregrinus, the subject of the present notice, a -man of academic culture and of a practical rather than speculative turn -of mind. Of the early years of Peregrinus nothing is known save that he -studied probably at the University of Paris, and that he graduated with -the highest scholastic honors. He owes his surname to the village of -Maricourt, in Picardy, and the appellation Peregrinus, or Pilgrim, to -his having visited the Holy Land as a member of one of the crusading -expeditions of the time. - -In 1269 we find him in the engineering corps of the French army then -besieging Lucera, in Southern Italy, which had revolted from the -authority of its French master, Charles of Anjou. To Peregrinus was -assigned the work of fortifying the camp and laying mines as well as of -constructing engines for projecting stones and fire-balls into the -beleaguered city. - -It was in the midst of such warlike preoccupations that the idea seems -to have occurred to him of devising a piece of mechanism to keep the -astronomical sphere of Archimedes in uniform rotation for a definite -time. In the course of his work over the new motor, Peregrinus was -gradually led to consider the more fascinating problem of perpetual -motion itself with the result that he showed, at least diagrammatically, -and to his own evident satisfaction, how a wheel might be driven round -forever by the power of magnetic attraction. - -Elated over his imaginary success, Peregrinus hastened to inform a -friend of his at home; and that his friend might the more readily -comprehend the mechanism of the motor and the functions of its parts, he -proceeds to set forth in a methodical manner all the properties of the -lodestone, most of which he himself had discovered. It is a fortunate -circumstance that this Picard friend of his was not a man learned in the -sciences, otherwise we would probably never have had the remarkable -exposition which Peregrinus gives of the phenomena and laws of -magnetism. This letter of 3,500 words is the first great landmark in the -domain of magnetic philosophy, the next being Gilbert’s _De Magnete_, in -1600. - -The letter was addressed from the trenches at Lucera, Southern Italy, in -August, 1269, to Sigerus de Foucaucourt, his “amicorum intimus,” the -dearest of friends. A more enlightened friend, however, than the knight -of Foucaucourt was Roger Bacon, who held Peregrinus in the very highest -esteem, as the following glowing testimony shows: “There are but two -perfect mathematicians,” wrote the English monk, “John of London and -Petrus de Maharne-Curia, a Picard.” Further on in his _Opus Tertium_, -Bacon thus appraises the merits of the Picard: “I know of only one -person who deserves praise for his work in experimental philosophy, for -he does not care for the discourses of men and their wordy warfare, but -quietly and diligently pursues the works of wisdom. Therefore, what -others grope after blindly, as bats in the evening twilight, this man -contemplates in all their brilliancy because he is a master of -experiment. Hence, he knows all natural science whether pertaining to -medicine and alchemy, or to matters celestial and terrestrial. He has -worked diligently in the smelting of ores as also in the working of -minerals; he is thoroughly acquainted with all sorts of arms and -implements used in military service and in hunting, besides which he is -skilled in agriculture and in the measurement of lands. It is impossible -to write a useful or correct treatise in experimental philosophy without -mentioning this man’s name. Moreover, he pursues knowledge for its own -sake; for if he wished to obtain royal favor, he could easily find -sovereigns who would honor and enrich him.” - -This last statement is worthy of the best utterances of the twentieth -century. Say what they will, the most ardent pleaders of our day for -original work and laboratory methods cannot surpass the Franciscan monk -of the thirteenth century in his denunciation of mere book learning or -in his advocacy of experiment and research, while in Peregrinus, the -mediævalist, they have Bacon’s impersonation of what a student of -science ought to be. Peregrinus was a hard worker, nor a mere theorizer, -preferring, Procrustean-like, to make theory fit the facts rather than -facts the theory; he was a brilliant discoverer who knew at the same -time how to use his discoveries for the benefit of mankind; he was a -pioneer of science and a leader in the progress of the world. - -An analysis of the “Epistola” shows that - -(_a_) Peregrinus was the first to assign a definite position to the -poles of a lodestone, and to give directions for determining which is -north and which south; - -(_b_) He proved that unlike poles attract each other, and that similar -ones repel; - -(_c_) He established by experiment that every fragment of a lodestone, -however small, is a complete magnet, thus anticipating one of our -fundamental laboratory illustrations of the molecular theory; - -(_d_) He recognized that a pole of a magnet may neutralize a weaker one -of the same name, and even reverse its polarity; - -(_e_) He was the first to pivot a magnetized needle and surround it with -a graduated circle, Figs. 2 and 3.[2] - -(_f_) He determined the position of an object by its magnetic bearing as -done to-day in compass surveying; and - -(_g_) He introduced into his perpetual motion machine, Fig. 4, the idea -of a magnetic motor, a clever idea, indeed, for a thirteenth century -engineer. - -This rapid summary will serve to show that the letter of Peregrinus is -one of great interest in physics as well as in navigation and geodesy. -For nearly three centuries, it lay unnoticed among the libraries of -Europe, but it did not escape Gilbert, who makes frequent mention of it -in his _De Magnete_, 1600; nor the illustrious Jesuit writers, Cabæus, -who refers to it in his _Philosophia Magnetica_, 1629, and Kircher, who -quotes from it in his _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 _De Natura Magnetis_, 1562, without a -word of acknowledgment. By this piece of fraud, Taisnier acquired -considerable celebrity, a fact that goes to show the meritorious -character of the work which he unscrupulously copied. - -This memorable letter is divided into two parts: the first contains ten -chapters on the general properties of the lodestone; the second has but -three chapters, and shows how the author proposed to use a lodestone for -the purpose of producing continuous rotation. - -There are many manuscript copies of the letter in European libraries: -the Bodleian has six; the Vatican, two; Trinity College, Dublin, one; -the Bibliothèque Nationale, Paris, one; Leyden, Geneva and Turin, one -each. The Leyden MS. has acquired special notoriety from a passage which -appears near the end of it in which reference is made to magnetic -declination and its value given: but Prof. W. Wenckebach, of The Hague, -has shown[3] that the lines are spurious, having been interpolated in -the manuscript in the early part of the sixteenth century. - -The Leyden manuscript has also led some writers to believe in a -fictitious author of the letter, one Peter Adsiger, or Petrus Adsigerus. -As said above, Sigerus was the name of his countryman, to whom -Peregrinus addressed his letter, the _Epistola ad Sigerum_, from the -trenches at Lucera, in August, 1269. - -Magnetic declination was unknown to Peregrinus, else he would not have -written the following words: “Wherever a man may be, he finds the -lodestone pointing to the heavens in accordance with the position of the -meridian” (Chapter X). Of course, the geographical meridian is the one -here meant, as the necessity of a distinct magnetic meridian had not yet -occurred to any one. - -Nor was this important magnetic element known to Columbus when he sailed -from the shores of the Old World in 1492 as appears from the surprise -with which he noticed the deviation of the needle from North as well as -from the consternation of his pilots. Columbus has the unquestionable -merit of being the first to observe and record the change of declination -with change of place. - -The first printed edition of the Epistola, now very rare, was prepared -by Achilles Gasser, a physician of Lindau, a man well versed in -mathematics, astronomy, history and philosophy. The work was printed in -Augsburg in 1558. A copy of this early print is among the treasures of -the Wheeler collection in the library of the American Institute of -Electrical Engineers, New York. It was from this text that the -translation which follows was made. - -Besides the Latin edition of Gasser, 1558, there is also that of Libri -in his _Histoire des Sciences Mathématiques_, 1838; of Bertelli, 1868, -and Hellmann, 1898. Bertelli’s is a learned and exhaustive work in which -the Barnabite monk, sometimes called by mistake, Barnabita, instead of -Bertelli, collates and compares the readings of the two Vatican codices -with other texts, adding copious references and explanatory notes. It -appeared in the _Bulletino di Bibliografia e di Storia delle Scienze -Matematiche e Fisiche_ for 1868. - -Of translations, we have that which Richard Eden made from Taisnier’s -pirated extracts, the first dated edition appearing in 1579. Cavallo’s -_Treatise on Magnetism_, 1800, also contains some of the more remarkable -passages. The only complete English translation that we have, appeared -in 1902 from the scholarly pen of Prof. Silvanus P. Thompson, of London. -It is an _édition de luxe_ beautifully rubricated, but limited to 250 -copies. The translation was based on the texts of Gasser and Hellmann, -amended by reference to a manuscript in the author’s possession, dated -1391. We are informed that Mr. Fleury P. Mottelay, of New York, the -learned translator of Gilbert’s _De Magnete_, possesses a manuscript -version by Prof. Peirce, of Harvard, of the Paris codex, of which he -made a careful study in an endeavor to decipher the illegible parts. - - - - - PART I - - - - - THE LETTER OF - PEREGRINUS - - - PART I - CHAPTER I - PURPOSE OF THIS WORK - -Dearest of Friends: - -At your earnest request, I will now make known to you, in an unpolished -narrative, the undoubted though hidden virtue of the lodestone, -concerning which philosophers up to the present time give us no -information, because it is characteristic of good things to be hidden in -darkness until they are brought to light by application to public -utility. Out of affection for you, I will write in a simple style about -things entirely unknown to the ordinary individual. Nevertheless I will -speak only of the manifest properties of the lodestone, because this -tract will form part of a work on the construction of philosophical -instruments. The disclosing of the hidden properties of this stone is -like the art of the sculptor by which he brings figures and seals into -existence. Although I may call the matters about which you inquire -evident and of inestimable value, they are considered by common folk to -be illusions and mere creations of the imagination. But the things that -are hidden from the multitude will become clear to astrologers and -students of nature, and will constitute their delight, as they will also -be of great help to those that are old and more learned. - - - CHAPTER II - QUALIFICATIONS OF THE EXPERIMENTER - -You must know, my dear friend, that whoever wishes to experiment, should -be acquainted with the nature of things, and should not be ignorant of -the motion of the celestial bodies. He must also be skilful in -manipulation in order that, by means of this stone, he may produce these -marvelous effects. Through his own industry he can, to some extent, -indeed, correct the errors that a mathematician would inevitably make if -he were lacking in dexterity. Besides, in such occult experimentation, -great skill is required, for very frequently without it the desired -result cannot be obtained, because there are many things in the domain -of reason which demand this manual dexterity. - - - CHAPTER III - CHARACTERISTICS OF A GOOD LODESTONE - -The lodestone selected must be distinguished by four marks—its color, -homogeneity, weight and strength. Its color should be iron-like, pale, -slightly bluish or indigo, just as polished iron becomes when exposed to -the corroding atmosphere. I have never yet seen a stone of such -description which did not produce wonderful effects. Such stones are -found most frequently in northern countries, as is attested by sailors -who frequent places on the northern seas, notably in Normandy, Flanders -and Picardy. This stone should also be of homogeneous material; one -having reddish spots and small holes in it should not be chosen; yet a -lodestone is hardly ever found entirely free from such blemishes. On -account of uniformity in its composition and the compactness of its -innermost parts, such a stone is heavy and therefore more valuable. Its -strength is known by its vigorous attraction for a large mass of iron; -further on I will explain the nature of this attraction. If you chance -to see a stone with all these characteristics, secure it if you can. - - - CHAPTER IV - HOW TO DISTINGUISH THE POLES OF A LODESTONE - -I wish to inform you that this stone bears in itself the likeness of the -heavens, as I will now clearly demonstrate. There are in the heavens two -points more important than all others, because on them, as on pivots, -the celestial sphere revolves: these points are called, one the arctic -or north pole, the other the antarctic or south pole. Similarly you must -fully realize that in this stone there are two points styled -respectively the north pole and the south pole. If you are very careful, -you can discover these two points in a general way. One method for doing -so is the following: With an instrument with which crystals and other -stones are rounded let a lodestone be made into a globe and then -polished. A needle or an elongated piece of iron is then placed on top -of the lodestone and a line is drawn in the direction of the needle or -iron, thus dividing the stone into two equal parts. The needle is next -placed on another part of the stone and a second median line drawn. If -desired, this operation may be performed on many different parts, and -undoubtedly all these lines will meet in two points just as all meridian -or azimuth circles meet in the two opposite poles of the globe. One of -these is the north pole, the other the south pole. Proof of this will be -found in a subsequent chapter of this tract. - -A second method for determining these important points is this: Note the -place on the above-mentioned spherical lodestone where the point of the -needle clings most frequently and most strongly; for this will be one of -the poles as discovered by the previous method. In order to determine -this point exactly, break off a small piece of the needle or iron so as -to obtain a fragment about the length of two fingernails; then put it on -the spot which was found to be the pole by the former operation. If the -fragment stands perpendicular to the stone, then that is, -unquestionably, the pole sought; if not, then move the iron fragment -about until it becomes so; mark this point carefully; on the opposite -end another point may be found in a similar manner. If all this has been -done rightly, and if the stone is homogeneous throughout and a choice -specimen, these two points will be diametrically opposite, like the -poles of a sphere. - - - CHAPTER V -HOW TO DISCOVER THE POLES OF A LODESTONE AND HOW TO TELL WHICH IS NORTH - AND WHICH SOUTH - -The poles of a lodestone having been located in a general way, you will -determine which is north and which south in the following manner: Take a -wooden vessel rounded like a platter or dish, and in it place the stone -in such a way that the two poles will be equidistant from the edge of -the vessel; then place the dish in another and larger vessel full of -water, so that the stone in the first-mentioned dish may be like a -sailor in a boat. The second vessel should be of considerable size so -that the first may resemble a ship floating in a river or on the sea. I -insist upon the larger size of the second vessel in order that the -natural tendency of the lodestone may not be impeded by contact of one -vessel against the sides of the other. When the stone has been thus -placed, it will turn the dish round until the north pole lies in the -direction of the north pole of the heavens, and the south pole of the -stone points to the south pole of the heavens. Even if the stone be -moved a thousand times away from its position, it will return thereto a -thousand times, as by natural instinct. Since the north and south parts -of the heavens are known, these same points will then be easily -recognized in the stone because each part of the lodestone will turn to -the corresponding one of the heavens. - - - CHAPTER VI - HOW ONE LODESTONE ATTRACTS ANOTHER - -When you have discovered the north and the south pole in your lodestone, -mark them both carefully, so that by means of these indentations they -may be distinguished whenever necessary. Should you wish to see how one -lodestone attracts another, then, with two lodestones selected and -prepared as mentioned in the preceding chapter, proceed as follows: -Place one in its dish that it may float about as a sailor in a skiff, -and let its poles which have already been determined be equidistant from -the horizon, i. e., from the edge of the vessel. Taking the other stone -in your hand, approach its north pole to the south pole of the lodestone -floating in the vessel; the latter will follow the stone in your hand as -if longing to cling to it. If, conversely, you bring the south end of -the lodestone in your hand toward the north end of the floating -lodestone, the same phenomenon will occur; namely, the floating -lodestone will follow the one in your hand. Know then that this is the -law: the north pole of one lodestone attracts the south pole of another, -while the south pole attracts the north. Should you proceed otherwise -and bring the north pole of one near the north pole of another, the one -you hold in your hand will seem to put the floating one to flight. If -the south pole of one is brought near the south pole of another, the -same will happen. This is because the north pole of one seeks the south -pole of the other, and therefore repels the north pole. A proof of this -is that finally the north pole becomes united with the south pole. -Likewise if the south pole is stretched out towards the south pole of -the floating lodestone, you will observe the latter to be repelled, -which does not occur, as said before, when the north pole is extended -towards the south. Hence the silliness of certain persons is manifest, -who claim that just as scammony attracts jaundice on account of a -similarity between them, so one lodestone attracts another even more -strongly than it does iron, a fact which they suppose to be false -although really true as shown by experiment. - - - CHAPTER VII - HOW IRON TOUCHED BY A LODESTONE TURNS TOWARDS THE POLES OF THE WORLD - -It is well known to all who have made the experiment, that when an -elongated piece of iron has touched a lodestone and is then fastened to -a light block of wood or to a straw and made float on water, one end -will turn to the star which has been called the Sailor’s star because it -is near the pole; the truth is, however, that it does not point to the -star but to the pole itself. A proof of this will be furnished in a -following chapter. The other end of the iron will point in an opposite -direction. But as to which end of the iron will turn towards the north -and which to the south, you will observe that that part of the iron -which has touched the south pole of the lodestone will point to the -north and conversely, that part which had been in contact with the north -pole will turn to the south. Though this appears marvelous to the -uninitiated, yet it is known with certainty to those who have tried the -experiment. - - - CHAPTER VIII - HOW A LODESTONE ATTRACTS IRON - -If you wish the stone, according to its natural desire, to attract iron, -proceed as follows: Mark the north end of the iron and towards this end -approach the south pole of the stone, when it will be found to follow -the latter. Or, on the contrary, to the south part of the iron present -the north pole of the stone and the latter will attract it without any -difficulty. Should you, however, do the opposite, namely, if you bring -the north end of the stone towards the north pole of the iron, you will -notice the iron turn round until its south pole unites with the north -end of the lodestone. The same thing will occur when the south end of -the lodestone is brought near the south pole of the iron. Should force -be exerted at either pole, so that when the south pole of the iron is -made touch the south end of the stone, then the virtue in the iron will -be easily altered in such a manner that what was before the south end -will now become the north and conversely. The cause is that the last -impression acts, confounds, or counteracts and alters the force of the -original movement. - - - CHAPTER IX - WHY THE NORTH POLE OF ONE LODESTONE ATTRACTS THE SOUTH POLE OF ANOTHER - AND VICE VERSA - -As already stated, the north pole of one lodestone attracts the south -pole of another and conversely; in this case the virtue of the stronger -becomes active, whilst that of the weaker becomes obedient or passive. I -consider the following to be the cause of this phenomenon: the active -agent requires a passive subject, not merely to be joined to it, but -also to be united with it, so that the two make but one by nature. In -the case of this wonderful lodestone this may be shown in the following -manner: Take a lodestone which you may call _A D_, in which _A_ is the -north pole and _D_ the south; cut this stone into two parts, so that you -may have two distinct stones; place the stone having the pole _A_ so -that it may float on water and you will observe that _A_ turns towards -the north as before; the breaking did not destroy the properties of the -parts of the stone, since it is homogeneous; hence it follows that the -part of the stone at the point of fracture, which may be marked _B_, -must be a south pole; this broken part of which we are now speaking may -be called _A B_. The other, which contains _D_, should then be placed so -as to float on water, when you will see _D_ point towards the south -because it is a south pole; but the other end at the point of fracture, -lettered _C_, will be a north pole; this stone may now be named _C D_. -If we consider the first stone as the active agent, then the second, or -_C D_, will be the passive subject. You will also notice that the ends -of the two stones which before their separation were together, after -breaking will become one a north pole and the other a south pole. If now -these same broken portions are brought near each other, one will attract -the other, so that they will again be joined at the points _B_ and _C_, -where the fracture occurred. Thus, by natural instinct, one single stone -will be formed as before. This may be demonstrated fully by cementing -the parts together, when the same effects will be produced as before the -stone was broken. As you will perceive from this experiment, the active -agent desires to become one with the passive subject because of the -similarity that exists between them. Hence _C_, being a north pole, must -be brought close to _B_, so that the agent and its subject may form one -and the same straight line in the order _A B_, _C D_ and _B_ and _C_ -being at the same point. In this union the identity of the extreme parts -is retained and preserved just as they were at first; for _A_ is the -north pole in the entire line as it was in the divided one; so also _D_ -is the south pole as it was in the divided passive subject, but _B_ and -_C_ have been made effectually into one. In the same way it happens that -if _A_ be joined to _D_ so as to make the two lines one, in virtue of -this union due to attraction in the order _C D A B_, then _A_ and _D_ -will constitute but one point, the identity of the extreme parts will -remain unchanged just as they were before being brought together, for -_C_ is a north pole and _B_ a south, as during their separation. If you -proceed in a different fashion, this identity or similarity of parts -will not be preserved; for you will perceive that if _C_, a north pole, -be joined to _A_, a north pole, contrary to the demonstrated truth, and -from these two lines a single one, _B A C D_, is formed, as _D_ was a -south pole before the parts were united, it is then necessary that the -other extremity should be a north pole, and as _B_ is a south pole, the -identity of the parts of the former similarity is destroyed. If you make -_B_ the south pole as it was before they united, then _D_ must become -north, though it was south in the original stone; in this way neither -the identity nor similarity of parts is preserved. It is becoming that -when the two are united into one, they should bear the same likeness as -the agent, otherwise nature would be called upon to do what is -impossible. The same incongruity would occur if you were to join _B_ -with _D_ so as to make the line _A B D C_, as is plain to any person who -reflects a moment. Nature, therefore, aims at being and also at acting -in the best manner possible; it selects the former motion and order -rather than the second because the identity is better preserved. From -all this it is evident why the north pole attracts the south and -conversely, and also why the south pole does not attract the south pole -and the north pole does not attract the north. - - - CHAPTER X - AN INQUIRY INTO THE CAUSE OF THE NATURAL VIRTUE OF THE LODESTONE - -Certain persons who were but poor investigators of nature held the -opinion that the force with which a lodestone draws iron, is found in -the mineral veins themselves from which the stone is obtained; whence -they claim that the iron turns towards the poles of the earth, only -because of the numerous iron mines found there. But such persons are -ignorant of the fact that in many different parts of the globe the -lodestone is found; from which it would follow that the iron needle -should turn in different directions according to the locality; but this -is contrary to experience. Secondly, these individuals do not seem to -know that the places under the poles are uninhabitable because there -one-half the year is day and the other half night. Hence it is most -silly to imagine that the lodestone should come to us from such places. -Since the lodestone points to the south as well as to the north, it is -evident from the foregoing chapters that we must conclude that not only -from the north pole but also from the south pole rather than from the -veins of the mines virtue flows into the poles of the lodestone. This -follows from the consideration that wherever a man may be, he finds the -stone pointing to the heavens in accordance with the position of the -meridian; but all meridians meet in the poles of the world; hence it is -manifest that from the poles of the world, the poles of the lodestone -receive their virtue. Another necessary consequence of this is that the -needle does not point to the pole star, since the meridians do not -intersect in that star but in the poles of the world. In every region, -the pole star is always found outside the meridian except twice in each -complete revolution of the heavens. From all these considerations, it is -clear that the poles of the lodestone derive their virtue from the poles -of the heavens. As regards the other parts of the stone, the right -conclusion is, that they obtain their virtue from the other parts of the -heavens, so that we may infer that not only the poles of the stone -receive their virtue and influence from the poles of the world, but -likewise also the other parts, or the entire stone from the entire -heavens. You may test this in the following manner: A round lodestone on -which the poles are marked is placed on two sharp styles as pivots -having one pivot under each pole so that the lodestone may easily -revolve on these pivots. Having done this, make sure that it is equally -balanced and that it turns smoothly on the pivots. Repeat this several -times at different hours of the day and always with the utmost care. -Then place the stone with its axis in the meridian, the poles resting on -the pivots. Let it be moved after the manner of bracelets so that the -elevation and depression of the poles may equal the elevation and -depressions of the poles of the heavens of the place in which you are -experimenting. If now the stone be moved according to the motion of the -heavens, you will be delighted in having discovered such a wonderful -secret; but if not, ascribe the failure to your own lack of skill rather -than to a defect in nature. Moreover, in this position I consider the -strength of the lodestone to be best preserved. When it is placed -differently, i. e., not in the meridian, I think its virtue is weakened -or obscured rather than maintained. With such an instrument you will -need no timepiece, for by it you can know the ascendant at any hour you -please, as well as all other dispositions of the heavens which are -sought for by astrologers. - - - - - PART II - - - PART II - CHAPTER I - THE CONSTRUCTION OF AN INSTRUMENT FOR MEASURING THE AZIMUTH OF THE SUN - THE MOON OR ANY STAR ON THE HORIZON - -Having fully examined all the properties of the lodestone and the -phenomena connected therewith, let us now come to those instruments -which depend for their operation on the knowledge of those facts. Take a -rounded lodestone,[4] and after determining its poles in the manner -already mentioned, file its two sides so that it becomes elongated at -its poles and occupies less space. The lodestone prepared in this wise -is then enclosed within two capsules after the fashion of a mirror. Let -these capsules be so joined together that they cannot be separated and -that water cannot enter; they should be made of light wood and fastened -with cement suited to the purpose. Having done this, place them in a -large vessel of water on the edges of which the two parts of the world, -i. e., the north and south points, have been found and marked. These -points may be united by a thread stretched across from north to south. -Then float the capsules and place a smooth strip of wood over them in -the manner of a diameter. Move the strip until it is equally distant -from the meridian-line, previously determined and marked by a thread, or -else until it coincides therewith. Then mark a line on the capsules -according to the position of the strip, and this will indicate forever -the meridian of that place. Let this line be divided at its middle by -another cutting it at right angles, which will give the east and west -line; thus the four cardinal points will be determined and indicated on -the edge of the capsules. Each quarter is to be subdivided into 90 -parts, making 360 in the circumference of the capsules. Engrave these -divisions on them as usually done on the back of an astrolabe. On the -top or edge of the capsules thus marked place a thin ruler like the -pointer on the back of the astrolabe; instead of the sights attach two -perpendicular pins, one at each end. If, therefore, you desire to take -the azimuth of the sun, place the capsules in water and let them move -freely until they come to rest in their natural position. Hold them -firmly in one hand, while with the other you move the ruler until the -shadow of the pins falls along the length of the ruler; then the end of -the ruler which is towards the sun will indicate the azimuth of the sun. -Should it be windy, let the capsules be covered with a suitable vessel -until they have taken their position north and south. The same method, -namely, by sighting, may be followed at night for determining the -azimuth of the moon and stars; move the ruler until the ends of the pins -are in the same line with the moon or star; the end of the ruler will -then indicate the azimuth just as in the case of the sun. By means of -the azimuth may then be determined the hour of the day, the ascendant, -and all those other things usually determined by the astrolabe. A form -of the instrument is shown in the following figure. - - [Illustration: FIG. 1.—AZIMUTH COMPASS] - - - CHAPTER II - THE CONSTRUCTION OF A BETTER INSTRUMENT FOR THE SAME PURPOSE - -In this chapter I will describe the construction of a better and more -efficient instrument. Select a vessel of wood, brass or any solid -material you like, circular in shape, moderate in size, shallow but of -sufficient width, with a cover of some transparent substance, such as -glass or crystal; it would be even better to have both the vessel and -the cover transparent. At the centre of this vessel fasten a thin axis -of brass or silver, having its extremities in the cover above and the -vessel below. At the middle of this axis let there be two apertures at -right angles to each other; through one of them pass an iron stylus or -needle, through the other a silver or brass needle crossing the iron one -at right angles. Divide the cover first into four parts and subdivide -these into 90 parts, as was mentioned in describing the former -instrument. Mark the parts north, south, east and west. Add thereto a -ruler of transparent material with pins at each end. After this bring -either the north or the south pole of a lodestone near the cover so that -the needle may be attracted and receive its virtue from the lodestone. -Then turn the vessel until the needle stands in the north and south line -already marked on the instrument; after which turn the ruler towards the -sun if day-time, and towards the moon and stars at night, as described -in the preceding chapter. By means of this instrument you can direct -your course towards cities and islands and any other place wherever you -may wish to go by land or sea, provided the latitude and longitude of -the places are known to you. How iron remains suspended in air by virtue -of the lodestone, I will explain in my book on the action of mirrors. -Such, then, is the description of the instrument illustrated below. (See -Figs. 2 and 3.) - - [Illustration: FIG. 2.—DOUBLE-PIVOTED NEEDLE] - - [Illustration: FIG. 3.—PIVOTED COMPASS] - - - CHAPTER III - THE ART OF MAKING A WHEEL OF PERPETUAL MOTION - -In this chapter I will make known to you the construction of a wheel -which in a remarkable manner moves continuously. I have seen many -persons vainly busy themselves and even becoming exhausted with much -labor in their endeavors to invent such a wheel. But these invariably -failed to notice that by means of the virtue or power of the lodestone -all difficulty can be overcome. For the construction of such a wheel, -take a silver capsule like that of a concave mirror, and worked on the -outside with fine carving and perforations, not only for the sake of -beauty, but also for the purpose of diminishing its weight. You should -manage also that the eye of the unskilled may not perceive what is -cunningly placed inside. Within let there be iron nails or teeth of -equal weight fastened to the periphery of the wheel in a slanting -direction, close to one another so that their distance apart may not be -more than the thickness of a bean or a pea; the wheel itself must be of -uniform weight throughout. Fasten the middle of the axis about which the -wheel revolves so that the said axis may always remain immovable. Add -thereto a silver bar, and at its extremity affix a lodestone placed -between two capsules and prepared in the following way: When it has been -rounded and its poles marked as said before, let it be shaped like an -egg; leaving the poles untouched, file down the intervening parts so -that thus flattened and occupying less space, it may not touch the sides -of the capsules when the wheel revolves. Thus prepared, let it be -attached to the silver rod just as a precious stone is placed in a ring; -let the north pole be then turned towards the teeth or cogs of the wheel -somewhat slantingly so that the virtue of the stone may not flow -diametrically into the iron teeth, but at a certain angle; consequently -when one of the teeth comes near the north pole and owing to the impetus -of the wheel passes it, it then approaches the south pole from which it -is rather driven away than attracted, as is evident from the law given -in a preceding chapter. Therefore such a tooth would be constantly -attracted and constantly repelled. - - [Illustration: FIG. 4.—PERPETUAL MOTION WHEEL] - -In order that the wheel may do its work more speedily, place within the -box a small rounded weight made of brass or silver of such a size that -it may be caught between each pair of teeth; consequently as the -movement of the wheel is continuous in one direction, so the fall of the -weight will be continuous in the other. Being caught between the teeth -of a wheel which is continuously revolving, it seeks the centre of the -earth in virtue of its own weight, thereby aiding the motion of the -teeth and preventing them from coming to rest in a direct line with the -lodestone. Let the places between the teeth be suitably hollowed out so -that they may easily catch the body in its fall, as shown in the diagram -above. (Fig. 4.) - -Farewell: finished in camp at the siege of Lucera on the eighth day of -August, Anno Domini MCCLXIX. - - - - - NOTES - - - EARLY REFERENCES TO THE MARINER’S COMPASS - -The following are the passages referred to in the introductory notice: - -Abbot Neckam (1157-1217), in his _De Naturis Rerum_, writes: - -“The sailors, moreover, as they sail over the sea, when in cloudy -weather they can no longer profit by the light of the sun, or when the -world is wrapped up in the darkness of the shades of night and they are -ignorant to what point their ship’s course is directed, these mariners -touch the lodestone with a needle, which (the needle) is whirled round -in a circle until when its motion ceases, its point looks direct to the -north. (_Cuspis ipsius septentrionalem plagam respiciat._)” - -In his _De Utensilibus_, we read: - -“Among other stores of a ship, there must be a needle mounted on a dart -(_habeat etiam acum jaculo superpositam_) which will oscillate and turn -until the point looks to the north, and the sailors will thus know how -to direct their course when the pole star is concealed through the -troubled state of the atmosphere.”[5] - -Alexander Neckam was born at St. Albans in 1157, joined the Augustinian -Order and taught in the University of Paris from 1180 to 1187, after -which he returned to England to take charge of a College of his Order at -Dunstable. He was elected Abbot of Cirencester in 1213 and died at -Kemsey, near Worcester, in 1217. - - -The satirical poem of Guyot de Provins, written about 1208, contains the -following passage: - - The mariners employ an art which cannot deceive, - By the property of the lodestone, - An ugly stone and brown, - To which iron joints itself willingly - They have; they attend to where it points - After they have applied a needle to it; - And they lay the latter on a straw - And put it simply in the water - Where the straw makes it float. - Then the point turns direct - To the star with such certainty - That no man will ever doubt it, - Nor will it ever go wrong. - When the sea is dark and hazy, - That one sees neither star nor moon, - Then they put a light by the needle - And have no fear of losing their way. - The point turns towards the star; - And the mariners are taught - To follow the right way. - It is an art which cannot fail. - -Provins, from which Guyot took his surname, was a small town in the -vicinity of Paris. - - -Cardinal Jacques de Vitry, in his _Historia Orientalis_, Cap. 89, -writes: - -“An iron needle, after having been in contact with the lodestone, turns -towards the north star, so that it is very necessary for those who -navigate the seas.” - -Jacques de Vitry was born at Argenteuil, near Paris, joined the fourth -crusade, became Bishop of Ptolemais, and died in Rome in 1244. He wrote -his “Description of Palestine,” which forms the first book of his -_Historia Orientalis_, in the East, between 1215 and 1220. - - -Albertus Magnus (1193-1280) in his _De Mineralibus_, Lib. II., Tract 3, -Cap. 6, writes: - -“It is the end of the lodestone which makes the iron that touched it -turn to the north (_ad zoron_) and which is of use to mariners; but the -other end of the needle turns toward the south (_ad aphron_).” - -This illustrious Bavarian schoolman joined the Dominican Order in his -youth, lectured to great audiences in Cologne, became bishop of -Ratisbonne in 1260, and died in 1280. Thomas Aquinas the greatest of -schoolmen, was among his pupils. - - -In the Spanish code of laws, begun in 1256, during the reign of Alfonso -el Sabio, and known as _Las Siete Partidas_, we read: - -“Just as mariners are guided during the night by the needle, which -replaces for them the shores and pole star alike, by showing them the -course to pursue both in fair weather and foul, so those who are called -upon to advise the King must always be guided by a spirit of justice.” - - -Brunetto Latini, in his _Trésor des Sciences_, 1260, writes: - -“The sailors navigate the seas guided by the two stars called the -tramontanes, and each of the two parts of the lodestone directs the end -of the needle to the star to which that part itself turns.” - -Brunetto Latini (1230-1294) was a man of great eminence in the -thirteenth century; Dante was among his pupils at Florence. For -political reasons, he removed to Paris, where he wrote his _Trésor_ and -also his _Tesoretto_. He visited Roger Bacon at Oxford about 1260. - - -In his treatise _De Contemplatione_, begun in 1272, Raymond Lully -writes: - -“As the needle, after having touched the lodestone, turns to the north, -so the mariner’s needle (_acus nautica_) directs them over the sea.” - -Lully was born at Palma in the Island of Majorca in 1236; he joined the -Third Order of St. Francis, dying in 1315. - - -Ristoro d’Arezzo, in his _Libro della Composizione del Mundo_, written -in 1282, has the following: - -“Besides this, there is the needle which guides the mariner, and which -is itself directed by the star called the tramontane.”[6] - - -The following metrical translation of a poem by Guido Guinicelli, an -Italian priest, 1276, is from the pen of Dr. Park Benjamin, of New York: - - In what strange regions ’neath the polar star - May the great hills of massy lodestone rise, - Virtue imparting to the ambient air - To draw the stubborn iron; while afar - From that same stone, the hidden virtue flies - To turn the quivering needle to the Bear - In splendor blazing in the Northern skies. - -The above extracts show that the directive property of the magnetic -needle was well known in England, France, Germany, Spain and Italy in -the thirteenth century. In the passage from Neckam, the _acum jaculo -superpositam_ has been construed by some to mean a form of pivoted -needle, while in the letter of Peregrinus, 1269, the double pivoted form -is clearly described. - - - - - Footnotes - - -[1]With very few exceptions all the works referred to in this notice - will be found in the Wheeler Collection in the Library of the - American Institute of Electrical Engineers, New York. - -[2]It is probable that Flavio Gioja, an Italian pilot, some fifty years - later, added the compass-card and attached it to the magnet. - -[3]Annali di Matematica Pura ed Applicata, 1865. - -[4]A terrella, or earthkin. - -[5]The Chronicles and Memoirs of Great Britain and Ireland during the - Middle Ages, by Thomas Wright (1863). - -[6]The pole-star was thus named in the south of France and the north of - Italy because seen beyond the mountains (the Alps). - - - - - Transcriber’s Notes - - -—Retained publication and copyright information from the original; this - eBook is public-domain in the U.S. - -—Silently corrected a few palpable typographical errors. - -—In the text versions, enclosed italicized text in _underscore_. - - - - - - - -End of the Project Gutenberg EBook of The Letter of Petrus Peregrinus on the -Magnet, A.D. 1269, by Petrus Peregrinus - -*** END OF THIS PROJECT GUTENBERG EBOOK LETTER OF PETRUS PEREGRINUS ON MAGNET *** - -***** This file should be named 50524-0.txt or 50524-0.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/0/5/2/50524/ - -Produced by deaurider, Stephen Hutcheson, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The Letter of Petrus Peregrinus on the Magnet, A.D. 1269 - -Author: Petrus Peregrinus - -Translator: Brother Arnold - -Release Date: November 21, 2015 [EBook #50524] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK LETTER OF PETRUS PEREGRINUS ON MAGNET *** - - - - -Produced by deaurider, Stephen Hutcheson, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - - - - - THE LETTER OF - PETRUS - PEREGRINUS - ON THE MAGNET, A.D. 1269 - - - TRANSLATED BY - BROTHER ARNOLD, M.Sc. - PRINCIPAL OF LA SALLE INSTITUTE, TROY - WITH - INTRODUCTORY NOTICE - BY - BROTHER POTAMIAN, D.Sc. - PROFESSOR OF PHYSICS IN MANHATTAN - COLLEGE, NEW YORK - - - NEW YORK - McGRAW PUBLISHING COMPANY - MCMIV - - Copyright, 1904, by - McGraw Publishing Company - - - - - INTRODUCTORY - - -The magnetic lore of classic antiquity was scanty indeed, being limited -to the attraction which the lodestone manifests for iron. Lucretius -(99-55 B. C.), however, in his poetical dissertation on the magnet, -contained in _De Rerum Natura_, Book VI.[1] recognizes magnetic -repulsion, magnetic induction, and to some extent the magnetic field -with its lines of force, for in verse 1040 he writes: - - Oft from the magnet, too, the steel recedes, - Repelled by turns and re-attracted close. - -And in verse 1085: - - Its viewless, potent virtues men surprise; - Its strange effects, they view with wond'ring eyes - When without aid of hinges, links or springs - A pendant chain we hold of steely rings - Dropt from the stone--the stone the binding source-- - Ring cleaves to ring and owns magnetic force: - Those held above, the ones below maintain, - Circle 'neath circle downward draws in vain - Whilst free in air disports the oscillating chain. - -The poet Claudian (365-408 A. D.) wrote a short idyll on the attractive -virtue of the lodestone and its symbolism; St. Augustine (354-430), in -his work _De Civitate Dei_, records the fact that a lodestone, held -under a silver plate, draws after it a scrap of iron lying on the plate. -Abbot Neckam, the Augustinian (1157-1217), distinguishes between the -properties of the two ends of the lodestone, and gives in his _De -Utensilibus_, what is perhaps the earliest reference to the mariner's -compass that we have. Albertus Magnus, the Dominican (1193-1280), in his -treatise, _De Mineralibus_, enumerates different kinds of natural -magnets and states some of the properties commonly attributed to them; -the minstrel, Guyot de Provins, in a famous satirical poem, written -about 1208, refers to the directive quality of the lodestone and its use -in navigation, as do also Cardinal de Vitry in his _Historia Orientalis_ -(1215-1220); Brunetto Latini, poet, orator and philosopher, in his -_Trsor des Sciences_, a veritable library, written in Paris in 1260; -Raymond Lully, the Enlightened Doctor, in his treatise, _De -Contemplatione_, begun in 1272, and Guido Guinicelli, the poet-priest of -Bologna, who died in 1276. - -The authors of these learned works were too busy with the pen to find -time to devote to the close and prolonged study of natural phenomena -necessary for fruitful discovery, and so had to content themselves with -recording and discussing in their tomes the scientific knowledge of -their age without making any notable additions to it. - -But this was not the case with such contemporaries of theirs as Roger -Bacon, the Franciscan, and his Gallic friend, Pierre de Maricourt, -commonly called Petrus Peregrinus, the subject of the present notice, a -man of academic culture and of a practical rather than speculative turn -of mind. Of the early years of Peregrinus nothing is known save that he -studied probably at the University of Paris, and that he graduated with -the highest scholastic honors. He owes his surname to the village of -Maricourt, in Picardy, and the appellation Peregrinus, or Pilgrim, to -his having visited the Holy Land as a member of one of the crusading -expeditions of the time. - -In 1269 we find him in the engineering corps of the French army then -besieging Lucera, in Southern Italy, which had revolted from the -authority of its French master, Charles of Anjou. To Peregrinus was -assigned the work of fortifying the camp and laying mines as well as of -constructing engines for projecting stones and fire-balls into the -beleaguered city. - -It was in the midst of such warlike preoccupations that the idea seems -to have occurred to him of devising a piece of mechanism to keep the -astronomical sphere of Archimedes in uniform rotation for a definite -time. In the course of his work over the new motor, Peregrinus was -gradually led to consider the more fascinating problem of perpetual -motion itself with the result that he showed, at least diagrammatically, -and to his own evident satisfaction, how a wheel might be driven round -forever by the power of magnetic attraction. - -Elated over his imaginary success, Peregrinus hastened to inform a -friend of his at home; and that his friend might the more readily -comprehend the mechanism of the motor and the functions of its parts, he -proceeds to set forth in a methodical manner all the properties of the -lodestone, most of which he himself had discovered. It is a fortunate -circumstance that this Picard friend of his was not a man learned in the -sciences, otherwise we would probably never have had the remarkable -exposition which Peregrinus gives of the phenomena and laws of -magnetism. This letter of 3,500 words is the first great landmark in the -domain of magnetic philosophy, the next being Gilbert's _De Magnete_, in -1600. - -The letter was addressed from the trenches at Lucera, Southern Italy, in -August, 1269, to Sigerus de Foucaucourt, his "amicorum intimus," the -dearest of friends. A more enlightened friend, however, than the knight -of Foucaucourt was Roger Bacon, who held Peregrinus in the very highest -esteem, as the following glowing testimony shows: "There are but two -perfect mathematicians," wrote the English monk, "John of London and -Petrus de Maharne-Curia, a Picard." Further on in his _Opus Tertium_, -Bacon thus appraises the merits of the Picard: "I know of only one -person who deserves praise for his work in experimental philosophy, for -he does not care for the discourses of men and their wordy warfare, but -quietly and diligently pursues the works of wisdom. Therefore, what -others grope after blindly, as bats in the evening twilight, this man -contemplates in all their brilliancy because he is a master of -experiment. Hence, he knows all natural science whether pertaining to -medicine and alchemy, or to matters celestial and terrestrial. He has -worked diligently in the smelting of ores as also in the working of -minerals; he is thoroughly acquainted with all sorts of arms and -implements used in military service and in hunting, besides which he is -skilled in agriculture and in the measurement of lands. It is impossible -to write a useful or correct treatise in experimental philosophy without -mentioning this man's name. Moreover, he pursues knowledge for its own -sake; for if he wished to obtain royal favor, he could easily find -sovereigns who would honor and enrich him." - -This last statement is worthy of the best utterances of the twentieth -century. Say what they will, the most ardent pleaders of our day for -original work and laboratory methods cannot surpass the Franciscan monk -of the thirteenth century in his denunciation of mere book learning or -in his advocacy of experiment and research, while in Peregrinus, the -medivalist, they have Bacon's impersonation of what a student of -science ought to be. Peregrinus was a hard worker, nor a mere theorizer, -preferring, Procrustean-like, to make theory fit the facts rather than -facts the theory; he was a brilliant discoverer who knew at the same -time how to use his discoveries for the benefit of mankind; he was a -pioneer of science and a leader in the progress of the world. - -An analysis of the "Epistola" shows that - -(_a_) Peregrinus was the first to assign a definite position to the -poles of a lodestone, and to give directions for determining which is -north and which south; - -(_b_) He proved that unlike poles attract each other, and that similar -ones repel; - -(_c_) He established by experiment that every fragment of a lodestone, -however small, is a complete magnet, thus anticipating one of our -fundamental laboratory illustrations of the molecular theory; - -(_d_) He recognized that a pole of a magnet may neutralize a weaker one -of the same name, and even reverse its polarity; - -(_e_) He was the first to pivot a magnetized needle and surround it with -a graduated circle, Figs. 2 and 3.[2] - -(_f_) He determined the position of an object by its magnetic bearing as -done to-day in compass surveying; and - -(_g_) He introduced into his perpetual motion machine, Fig. 4, the idea -of a magnetic motor, a clever idea, indeed, for a thirteenth century -engineer. - -This rapid summary will serve to show that the letter of Peregrinus is -one of great interest in physics as well as in navigation and geodesy. -For nearly three centuries, it lay unnoticed among the libraries of -Europe, but it did not escape Gilbert, who makes frequent mention of it -in his _De Magnete_, 1600; nor the illustrious Jesuit writers, Cabus, -who refers to it in his _Philosophia Magnetica_, 1629, and Kircher, who -quotes from it in his _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 _De Natura Magnetis_, 1562, without a -word of acknowledgment. By this piece of fraud, Taisnier acquired -considerable celebrity, a fact that goes to show the meritorious -character of the work which he unscrupulously copied. - -This memorable letter is divided into two parts: the first contains ten -chapters on the general properties of the lodestone; the second has but -three chapters, and shows how the author proposed to use a lodestone for -the purpose of producing continuous rotation. - -There are many manuscript copies of the letter in European libraries: -the Bodleian has six; the Vatican, two; Trinity College, Dublin, one; -the Bibliothque Nationale, Paris, one; Leyden, Geneva and Turin, one -each. The Leyden MS. has acquired special notoriety from a passage which -appears near the end of it in which reference is made to magnetic -declination and its value given: but Prof. W. Wenckebach, of The Hague, -has shown[3] that the lines are spurious, having been interpolated in -the manuscript in the early part of the sixteenth century. - -The Leyden manuscript has also led some writers to believe in a -fictitious author of the letter, one Peter Adsiger, or Petrus Adsigerus. -As said above, Sigerus was the name of his countryman, to whom -Peregrinus addressed his letter, the _Epistola ad Sigerum_, from the -trenches at Lucera, in August, 1269. - -Magnetic declination was unknown to Peregrinus, else he would not have -written the following words: "Wherever a man may be, he finds the -lodestone pointing to the heavens in accordance with the position of the -meridian" (Chapter X). Of course, the geographical meridian is the one -here meant, as the necessity of a distinct magnetic meridian had not yet -occurred to any one. - -Nor was this important magnetic element known to Columbus when he sailed -from the shores of the Old World in 1492 as appears from the surprise -with which he noticed the deviation of the needle from North as well as -from the consternation of his pilots. Columbus has the unquestionable -merit of being the first to observe and record the change of declination -with change of place. - -The first printed edition of the Epistola, now very rare, was prepared -by Achilles Gasser, a physician of Lindau, a man well versed in -mathematics, astronomy, history and philosophy. The work was printed in -Augsburg in 1558. A copy of this early print is among the treasures of -the Wheeler collection in the library of the American Institute of -Electrical Engineers, New York. It was from this text that the -translation which follows was made. - -Besides the Latin edition of Gasser, 1558, there is also that of Libri -in his _Histoire des Sciences Mathmatiques_, 1838; of Bertelli, 1868, -and Hellmann, 1898. Bertelli's is a learned and exhaustive work in which -the Barnabite monk, sometimes called by mistake, Barnabita, instead of -Bertelli, collates and compares the readings of the two Vatican codices -with other texts, adding copious references and explanatory notes. It -appeared in the _Bulletino di Bibliografia e di Storia delle Scienze -Matematiche e Fisiche_ for 1868. - -Of translations, we have that which Richard Eden made from Taisnier's -pirated extracts, the first dated edition appearing in 1579. Cavallo's -_Treatise on Magnetism_, 1800, also contains some of the more remarkable -passages. The only complete English translation that we have, appeared -in 1902 from the scholarly pen of Prof. Silvanus P. Thompson, of London. -It is an _dition de luxe_ beautifully rubricated, but limited to 250 -copies. The translation was based on the texts of Gasser and Hellmann, -amended by reference to a manuscript in the author's possession, dated -1391. We are informed that Mr. Fleury P. Mottelay, of New York, the -learned translator of Gilbert's _De Magnete_, possesses a manuscript -version by Prof. Peirce, of Harvard, of the Paris codex, of which he -made a careful study in an endeavor to decipher the illegible parts. - - - - - PART I - - - - - THE LETTER OF - PEREGRINUS - - - PART I - CHAPTER I - PURPOSE OF THIS WORK - -Dearest of Friends: - -At your earnest request, I will now make known to you, in an unpolished -narrative, the undoubted though hidden virtue of the lodestone, -concerning which philosophers up to the present time give us no -information, because it is characteristic of good things to be hidden in -darkness until they are brought to light by application to public -utility. Out of affection for you, I will write in a simple style about -things entirely unknown to the ordinary individual. Nevertheless I will -speak only of the manifest properties of the lodestone, because this -tract will form part of a work on the construction of philosophical -instruments. The disclosing of the hidden properties of this stone is -like the art of the sculptor by which he brings figures and seals into -existence. Although I may call the matters about which you inquire -evident and of inestimable value, they are considered by common folk to -be illusions and mere creations of the imagination. But the things that -are hidden from the multitude will become clear to astrologers and -students of nature, and will constitute their delight, as they will also -be of great help to those that are old and more learned. - - - CHAPTER II - QUALIFICATIONS OF THE EXPERIMENTER - -You must know, my dear friend, that whoever wishes to experiment, should -be acquainted with the nature of things, and should not be ignorant of -the motion of the celestial bodies. He must also be skilful in -manipulation in order that, by means of this stone, he may produce these -marvelous effects. Through his own industry he can, to some extent, -indeed, correct the errors that a mathematician would inevitably make if -he were lacking in dexterity. Besides, in such occult experimentation, -great skill is required, for very frequently without it the desired -result cannot be obtained, because there are many things in the domain -of reason which demand this manual dexterity. - - - CHAPTER III - CHARACTERISTICS OF A GOOD LODESTONE - -The lodestone selected must be distinguished by four marks--its color, -homogeneity, weight and strength. Its color should be iron-like, pale, -slightly bluish or indigo, just as polished iron becomes when exposed to -the corroding atmosphere. I have never yet seen a stone of such -description which did not produce wonderful effects. Such stones are -found most frequently in northern countries, as is attested by sailors -who frequent places on the northern seas, notably in Normandy, Flanders -and Picardy. This stone should also be of homogeneous material; one -having reddish spots and small holes in it should not be chosen; yet a -lodestone is hardly ever found entirely free from such blemishes. On -account of uniformity in its composition and the compactness of its -innermost parts, such a stone is heavy and therefore more valuable. Its -strength is known by its vigorous attraction for a large mass of iron; -further on I will explain the nature of this attraction. If you chance -to see a stone with all these characteristics, secure it if you can. - - - CHAPTER IV - HOW TO DISTINGUISH THE POLES OF A LODESTONE - -I wish to inform you that this stone bears in itself the likeness of the -heavens, as I will now clearly demonstrate. There are in the heavens two -points more important than all others, because on them, as on pivots, -the celestial sphere revolves: these points are called, one the arctic -or north pole, the other the antarctic or south pole. Similarly you must -fully realize that in this stone there are two points styled -respectively the north pole and the south pole. If you are very careful, -you can discover these two points in a general way. One method for doing -so is the following: With an instrument with which crystals and other -stones are rounded let a lodestone be made into a globe and then -polished. A needle or an elongated piece of iron is then placed on top -of the lodestone and a line is drawn in the direction of the needle or -iron, thus dividing the stone into two equal parts. The needle is next -placed on another part of the stone and a second median line drawn. If -desired, this operation may be performed on many different parts, and -undoubtedly all these lines will meet in two points just as all meridian -or azimuth circles meet in the two opposite poles of the globe. One of -these is the north pole, the other the south pole. Proof of this will be -found in a subsequent chapter of this tract. - -A second method for determining these important points is this: Note the -place on the above-mentioned spherical lodestone where the point of the -needle clings most frequently and most strongly; for this will be one of -the poles as discovered by the previous method. In order to determine -this point exactly, break off a small piece of the needle or iron so as -to obtain a fragment about the length of two fingernails; then put it on -the spot which was found to be the pole by the former operation. If the -fragment stands perpendicular to the stone, then that is, -unquestionably, the pole sought; if not, then move the iron fragment -about until it becomes so; mark this point carefully; on the opposite -end another point may be found in a similar manner. If all this has been -done rightly, and if the stone is homogeneous throughout and a choice -specimen, these two points will be diametrically opposite, like the -poles of a sphere. - - - CHAPTER V -HOW TO DISCOVER THE POLES OF A LODESTONE AND HOW TO TELL WHICH IS NORTH - AND WHICH SOUTH - -The poles of a lodestone having been located in a general way, you will -determine which is north and which south in the following manner: Take a -wooden vessel rounded like a platter or dish, and in it place the stone -in such a way that the two poles will be equidistant from the edge of -the vessel; then place the dish in another and larger vessel full of -water, so that the stone in the first-mentioned dish may be like a -sailor in a boat. The second vessel should be of considerable size so -that the first may resemble a ship floating in a river or on the sea. I -insist upon the larger size of the second vessel in order that the -natural tendency of the lodestone may not be impeded by contact of one -vessel against the sides of the other. When the stone has been thus -placed, it will turn the dish round until the north pole lies in the -direction of the north pole of the heavens, and the south pole of the -stone points to the south pole of the heavens. Even if the stone be -moved a thousand times away from its position, it will return thereto a -thousand times, as by natural instinct. Since the north and south parts -of the heavens are known, these same points will then be easily -recognized in the stone because each part of the lodestone will turn to -the corresponding one of the heavens. - - - CHAPTER VI - HOW ONE LODESTONE ATTRACTS ANOTHER - -When you have discovered the north and the south pole in your lodestone, -mark them both carefully, so that by means of these indentations they -may be distinguished whenever necessary. Should you wish to see how one -lodestone attracts another, then, with two lodestones selected and -prepared as mentioned in the preceding chapter, proceed as follows: -Place one in its dish that it may float about as a sailor in a skiff, -and let its poles which have already been determined be equidistant from -the horizon, i. e., from the edge of the vessel. Taking the other stone -in your hand, approach its north pole to the south pole of the lodestone -floating in the vessel; the latter will follow the stone in your hand as -if longing to cling to it. If, conversely, you bring the south end of -the lodestone in your hand toward the north end of the floating -lodestone, the same phenomenon will occur; namely, the floating -lodestone will follow the one in your hand. Know then that this is the -law: the north pole of one lodestone attracts the south pole of another, -while the south pole attracts the north. Should you proceed otherwise -and bring the north pole of one near the north pole of another, the one -you hold in your hand will seem to put the floating one to flight. If -the south pole of one is brought near the south pole of another, the -same will happen. This is because the north pole of one seeks the south -pole of the other, and therefore repels the north pole. A proof of this -is that finally the north pole becomes united with the south pole. -Likewise if the south pole is stretched out towards the south pole of -the floating lodestone, you will observe the latter to be repelled, -which does not occur, as said before, when the north pole is extended -towards the south. Hence the silliness of certain persons is manifest, -who claim that just as scammony attracts jaundice on account of a -similarity between them, so one lodestone attracts another even more -strongly than it does iron, a fact which they suppose to be false -although really true as shown by experiment. - - - CHAPTER VII - HOW IRON TOUCHED BY A LODESTONE TURNS TOWARDS THE POLES OF THE WORLD - -It is well known to all who have made the experiment, that when an -elongated piece of iron has touched a lodestone and is then fastened to -a light block of wood or to a straw and made float on water, one end -will turn to the star which has been called the Sailor's star because it -is near the pole; the truth is, however, that it does not point to the -star but to the pole itself. A proof of this will be furnished in a -following chapter. The other end of the iron will point in an opposite -direction. But as to which end of the iron will turn towards the north -and which to the south, you will observe that that part of the iron -which has touched the south pole of the lodestone will point to the -north and conversely, that part which had been in contact with the north -pole will turn to the south. Though this appears marvelous to the -uninitiated, yet it is known with certainty to those who have tried the -experiment. - - - CHAPTER VIII - HOW A LODESTONE ATTRACTS IRON - -If you wish the stone, according to its natural desire, to attract iron, -proceed as follows: Mark the north end of the iron and towards this end -approach the south pole of the stone, when it will be found to follow -the latter. Or, on the contrary, to the south part of the iron present -the north pole of the stone and the latter will attract it without any -difficulty. Should you, however, do the opposite, namely, if you bring -the north end of the stone towards the north pole of the iron, you will -notice the iron turn round until its south pole unites with the north -end of the lodestone. The same thing will occur when the south end of -the lodestone is brought near the south pole of the iron. Should force -be exerted at either pole, so that when the south pole of the iron is -made touch the south end of the stone, then the virtue in the iron will -be easily altered in such a manner that what was before the south end -will now become the north and conversely. The cause is that the last -impression acts, confounds, or counteracts and alters the force of the -original movement. - - - CHAPTER IX - WHY THE NORTH POLE OF ONE LODESTONE ATTRACTS THE SOUTH POLE OF ANOTHER - AND VICE VERSA - -As already stated, the north pole of one lodestone attracts the south -pole of another and conversely; in this case the virtue of the stronger -becomes active, whilst that of the weaker becomes obedient or passive. I -consider the following to be the cause of this phenomenon: the active -agent requires a passive subject, not merely to be joined to it, but -also to be united with it, so that the two make but one by nature. In -the case of this wonderful lodestone this may be shown in the following -manner: Take a lodestone which you may call _A D_, in which _A_ is the -north pole and _D_ the south; cut this stone into two parts, so that you -may have two distinct stones; place the stone having the pole _A_ so -that it may float on water and you will observe that _A_ turns towards -the north as before; the breaking did not destroy the properties of the -parts of the stone, since it is homogeneous; hence it follows that the -part of the stone at the point of fracture, which may be marked _B_, -must be a south pole; this broken part of which we are now speaking may -be called _A B_. The other, which contains _D_, should then be placed so -as to float on water, when you will see _D_ point towards the south -because it is a south pole; but the other end at the point of fracture, -lettered _C_, will be a north pole; this stone may now be named _C D_. -If we consider the first stone as the active agent, then the second, or -_C D_, will be the passive subject. You will also notice that the ends -of the two stones which before their separation were together, after -breaking will become one a north pole and the other a south pole. If now -these same broken portions are brought near each other, one will attract -the other, so that they will again be joined at the points _B_ and _C_, -where the fracture occurred. Thus, by natural instinct, one single stone -will be formed as before. This may be demonstrated fully by cementing -the parts together, when the same effects will be produced as before the -stone was broken. As you will perceive from this experiment, the active -agent desires to become one with the passive subject because of the -similarity that exists between them. Hence _C_, being a north pole, must -be brought close to _B_, so that the agent and its subject may form one -and the same straight line in the order _A B_, _C D_ and _B_ and _C_ -being at the same point. In this union the identity of the extreme parts -is retained and preserved just as they were at first; for _A_ is the -north pole in the entire line as it was in the divided one; so also _D_ -is the south pole as it was in the divided passive subject, but _B_ and -_C_ have been made effectually into one. In the same way it happens that -if _A_ be joined to _D_ so as to make the two lines one, in virtue of -this union due to attraction in the order _C D A B_, then _A_ and _D_ -will constitute but one point, the identity of the extreme parts will -remain unchanged just as they were before being brought together, for -_C_ is a north pole and _B_ a south, as during their separation. If you -proceed in a different fashion, this identity or similarity of parts -will not be preserved; for you will perceive that if _C_, a north pole, -be joined to _A_, a north pole, contrary to the demonstrated truth, and -from these two lines a single one, _B A C D_, is formed, as _D_ was a -south pole before the parts were united, it is then necessary that the -other extremity should be a north pole, and as _B_ is a south pole, the -identity of the parts of the former similarity is destroyed. If you make -_B_ the south pole as it was before they united, then _D_ must become -north, though it was south in the original stone; in this way neither -the identity nor similarity of parts is preserved. It is becoming that -when the two are united into one, they should bear the same likeness as -the agent, otherwise nature would be called upon to do what is -impossible. The same incongruity would occur if you were to join _B_ -with _D_ so as to make the line _A B D C_, as is plain to any person who -reflects a moment. Nature, therefore, aims at being and also at acting -in the best manner possible; it selects the former motion and order -rather than the second because the identity is better preserved. From -all this it is evident why the north pole attracts the south and -conversely, and also why the south pole does not attract the south pole -and the north pole does not attract the north. - - - CHAPTER X - AN INQUIRY INTO THE CAUSE OF THE NATURAL VIRTUE OF THE LODESTONE - -Certain persons who were but poor investigators of nature held the -opinion that the force with which a lodestone draws iron, is found in -the mineral veins themselves from which the stone is obtained; whence -they claim that the iron turns towards the poles of the earth, only -because of the numerous iron mines found there. But such persons are -ignorant of the fact that in many different parts of the globe the -lodestone is found; from which it would follow that the iron needle -should turn in different directions according to the locality; but this -is contrary to experience. Secondly, these individuals do not seem to -know that the places under the poles are uninhabitable because there -one-half the year is day and the other half night. Hence it is most -silly to imagine that the lodestone should come to us from such places. -Since the lodestone points to the south as well as to the north, it is -evident from the foregoing chapters that we must conclude that not only -from the north pole but also from the south pole rather than from the -veins of the mines virtue flows into the poles of the lodestone. This -follows from the consideration that wherever a man may be, he finds the -stone pointing to the heavens in accordance with the position of the -meridian; but all meridians meet in the poles of the world; hence it is -manifest that from the poles of the world, the poles of the lodestone -receive their virtue. Another necessary consequence of this is that the -needle does not point to the pole star, since the meridians do not -intersect in that star but in the poles of the world. In every region, -the pole star is always found outside the meridian except twice in each -complete revolution of the heavens. From all these considerations, it is -clear that the poles of the lodestone derive their virtue from the poles -of the heavens. As regards the other parts of the stone, the right -conclusion is, that they obtain their virtue from the other parts of the -heavens, so that we may infer that not only the poles of the stone -receive their virtue and influence from the poles of the world, but -likewise also the other parts, or the entire stone from the entire -heavens. You may test this in the following manner: A round lodestone on -which the poles are marked is placed on two sharp styles as pivots -having one pivot under each pole so that the lodestone may easily -revolve on these pivots. Having done this, make sure that it is equally -balanced and that it turns smoothly on the pivots. Repeat this several -times at different hours of the day and always with the utmost care. -Then place the stone with its axis in the meridian, the poles resting on -the pivots. Let it be moved after the manner of bracelets so that the -elevation and depression of the poles may equal the elevation and -depressions of the poles of the heavens of the place in which you are -experimenting. If now the stone be moved according to the motion of the -heavens, you will be delighted in having discovered such a wonderful -secret; but if not, ascribe the failure to your own lack of skill rather -than to a defect in nature. Moreover, in this position I consider the -strength of the lodestone to be best preserved. When it is placed -differently, i. e., not in the meridian, I think its virtue is weakened -or obscured rather than maintained. With such an instrument you will -need no timepiece, for by it you can know the ascendant at any hour you -please, as well as all other dispositions of the heavens which are -sought for by astrologers. - - - - - PART II - - - PART II - CHAPTER I - THE CONSTRUCTION OF AN INSTRUMENT FOR MEASURING THE AZIMUTH OF THE SUN - THE MOON OR ANY STAR ON THE HORIZON - -Having fully examined all the properties of the lodestone and the -phenomena connected therewith, let us now come to those instruments -which depend for their operation on the knowledge of those facts. Take a -rounded lodestone,[4] and after determining its poles in the manner -already mentioned, file its two sides so that it becomes elongated at -its poles and occupies less space. The lodestone prepared in this wise -is then enclosed within two capsules after the fashion of a mirror. Let -these capsules be so joined together that they cannot be separated and -that water cannot enter; they should be made of light wood and fastened -with cement suited to the purpose. Having done this, place them in a -large vessel of water on the edges of which the two parts of the world, -i. e., the north and south points, have been found and marked. These -points may be united by a thread stretched across from north to south. -Then float the capsules and place a smooth strip of wood over them in -the manner of a diameter. Move the strip until it is equally distant -from the meridian-line, previously determined and marked by a thread, or -else until it coincides therewith. Then mark a line on the capsules -according to the position of the strip, and this will indicate forever -the meridian of that place. Let this line be divided at its middle by -another cutting it at right angles, which will give the east and west -line; thus the four cardinal points will be determined and indicated on -the edge of the capsules. Each quarter is to be subdivided into 90 -parts, making 360 in the circumference of the capsules. Engrave these -divisions on them as usually done on the back of an astrolabe. On the -top or edge of the capsules thus marked place a thin ruler like the -pointer on the back of the astrolabe; instead of the sights attach two -perpendicular pins, one at each end. If, therefore, you desire to take -the azimuth of the sun, place the capsules in water and let them move -freely until they come to rest in their natural position. Hold them -firmly in one hand, while with the other you move the ruler until the -shadow of the pins falls along the length of the ruler; then the end of -the ruler which is towards the sun will indicate the azimuth of the sun. -Should it be windy, let the capsules be covered with a suitable vessel -until they have taken their position north and south. The same method, -namely, by sighting, may be followed at night for determining the -azimuth of the moon and stars; move the ruler until the ends of the pins -are in the same line with the moon or star; the end of the ruler will -then indicate the azimuth just as in the case of the sun. By means of -the azimuth may then be determined the hour of the day, the ascendant, -and all those other things usually determined by the astrolabe. A form -of the instrument is shown in the following figure. - - [Illustration: FIG. 1.--AZIMUTH COMPASS] - - - CHAPTER II - THE CONSTRUCTION OF A BETTER INSTRUMENT FOR THE SAME PURPOSE - -In this chapter I will describe the construction of a better and more -efficient instrument. Select a vessel of wood, brass or any solid -material you like, circular in shape, moderate in size, shallow but of -sufficient width, with a cover of some transparent substance, such as -glass or crystal; it would be even better to have both the vessel and -the cover transparent. At the centre of this vessel fasten a thin axis -of brass or silver, having its extremities in the cover above and the -vessel below. At the middle of this axis let there be two apertures at -right angles to each other; through one of them pass an iron stylus or -needle, through the other a silver or brass needle crossing the iron one -at right angles. Divide the cover first into four parts and subdivide -these into 90 parts, as was mentioned in describing the former -instrument. Mark the parts north, south, east and west. Add thereto a -ruler of transparent material with pins at each end. After this bring -either the north or the south pole of a lodestone near the cover so that -the needle may be attracted and receive its virtue from the lodestone. -Then turn the vessel until the needle stands in the north and south line -already marked on the instrument; after which turn the ruler towards the -sun if day-time, and towards the moon and stars at night, as described -in the preceding chapter. By means of this instrument you can direct -your course towards cities and islands and any other place wherever you -may wish to go by land or sea, provided the latitude and longitude of -the places are known to you. How iron remains suspended in air by virtue -of the lodestone, I will explain in my book on the action of mirrors. -Such, then, is the description of the instrument illustrated below. (See -Figs. 2 and 3.) - - [Illustration: FIG. 2.--DOUBLE-PIVOTED NEEDLE] - - [Illustration: FIG. 3.--PIVOTED COMPASS] - - - CHAPTER III - THE ART OF MAKING A WHEEL OF PERPETUAL MOTION - -In this chapter I will make known to you the construction of a wheel -which in a remarkable manner moves continuously. I have seen many -persons vainly busy themselves and even becoming exhausted with much -labor in their endeavors to invent such a wheel. But these invariably -failed to notice that by means of the virtue or power of the lodestone -all difficulty can be overcome. For the construction of such a wheel, -take a silver capsule like that of a concave mirror, and worked on the -outside with fine carving and perforations, not only for the sake of -beauty, but also for the purpose of diminishing its weight. You should -manage also that the eye of the unskilled may not perceive what is -cunningly placed inside. Within let there be iron nails or teeth of -equal weight fastened to the periphery of the wheel in a slanting -direction, close to one another so that their distance apart may not be -more than the thickness of a bean or a pea; the wheel itself must be of -uniform weight throughout. Fasten the middle of the axis about which the -wheel revolves so that the said axis may always remain immovable. Add -thereto a silver bar, and at its extremity affix a lodestone placed -between two capsules and prepared in the following way: When it has been -rounded and its poles marked as said before, let it be shaped like an -egg; leaving the poles untouched, file down the intervening parts so -that thus flattened and occupying less space, it may not touch the sides -of the capsules when the wheel revolves. Thus prepared, let it be -attached to the silver rod just as a precious stone is placed in a ring; -let the north pole be then turned towards the teeth or cogs of the wheel -somewhat slantingly so that the virtue of the stone may not flow -diametrically into the iron teeth, but at a certain angle; consequently -when one of the teeth comes near the north pole and owing to the impetus -of the wheel passes it, it then approaches the south pole from which it -is rather driven away than attracted, as is evident from the law given -in a preceding chapter. Therefore such a tooth would be constantly -attracted and constantly repelled. - - [Illustration: FIG. 4.--PERPETUAL MOTION WHEEL] - -In order that the wheel may do its work more speedily, place within the -box a small rounded weight made of brass or silver of such a size that -it may be caught between each pair of teeth; consequently as the -movement of the wheel is continuous in one direction, so the fall of the -weight will be continuous in the other. Being caught between the teeth -of a wheel which is continuously revolving, it seeks the centre of the -earth in virtue of its own weight, thereby aiding the motion of the -teeth and preventing them from coming to rest in a direct line with the -lodestone. Let the places between the teeth be suitably hollowed out so -that they may easily catch the body in its fall, as shown in the diagram -above. (Fig. 4.) - -Farewell: finished in camp at the siege of Lucera on the eighth day of -August, Anno Domini MCCLXIX. - - - - - NOTES - - - EARLY REFERENCES TO THE MARINER'S COMPASS - -The following are the passages referred to in the introductory notice: - -Abbot Neckam (1157-1217), in his _De Naturis Rerum_, writes: - -"The sailors, moreover, as they sail over the sea, when in cloudy -weather they can no longer profit by the light of the sun, or when the -world is wrapped up in the darkness of the shades of night and they are -ignorant to what point their ship's course is directed, these mariners -touch the lodestone with a needle, which (the needle) is whirled round -in a circle until when its motion ceases, its point looks direct to the -north. (_Cuspis ipsius septentrionalem plagam respiciat._)" - -In his _De Utensilibus_, we read: - -"Among other stores of a ship, there must be a needle mounted on a dart -(_habeat etiam acum jaculo superpositam_) which will oscillate and turn -until the point looks to the north, and the sailors will thus know how -to direct their course when the pole star is concealed through the -troubled state of the atmosphere."[5] - -Alexander Neckam was born at St. Albans in 1157, joined the Augustinian -Order and taught in the University of Paris from 1180 to 1187, after -which he returned to England to take charge of a College of his Order at -Dunstable. He was elected Abbot of Cirencester in 1213 and died at -Kemsey, near Worcester, in 1217. - - -The satirical poem of Guyot de Provins, written about 1208, contains the -following passage: - - The mariners employ an art which cannot deceive, - By the property of the lodestone, - An ugly stone and brown, - To which iron joints itself willingly - They have; they attend to where it points - After they have applied a needle to it; - And they lay the latter on a straw - And put it simply in the water - Where the straw makes it float. - Then the point turns direct - To the star with such certainty - That no man will ever doubt it, - Nor will it ever go wrong. - When the sea is dark and hazy, - That one sees neither star nor moon, - Then they put a light by the needle - And have no fear of losing their way. - The point turns towards the star; - And the mariners are taught - To follow the right way. - It is an art which cannot fail. - -Provins, from which Guyot took his surname, was a small town in the -vicinity of Paris. - - -Cardinal Jacques de Vitry, in his _Historia Orientalis_, Cap. 89, -writes: - -"An iron needle, after having been in contact with the lodestone, turns -towards the north star, so that it is very necessary for those who -navigate the seas." - -Jacques de Vitry was born at Argenteuil, near Paris, joined the fourth -crusade, became Bishop of Ptolemais, and died in Rome in 1244. He wrote -his "Description of Palestine," which forms the first book of his -_Historia Orientalis_, in the East, between 1215 and 1220. - - -Albertus Magnus (1193-1280) in his _De Mineralibus_, Lib. II., Tract 3, -Cap. 6, writes: - -"It is the end of the lodestone which makes the iron that touched it -turn to the north (_ad zoron_) and which is of use to mariners; but the -other end of the needle turns toward the south (_ad aphron_)." - -This illustrious Bavarian schoolman joined the Dominican Order in his -youth, lectured to great audiences in Cologne, became bishop of -Ratisbonne in 1260, and died in 1280. Thomas Aquinas the greatest of -schoolmen, was among his pupils. - - -In the Spanish code of laws, begun in 1256, during the reign of Alfonso -el Sabio, and known as _Las Siete Partidas_, we read: - -"Just as mariners are guided during the night by the needle, which -replaces for them the shores and pole star alike, by showing them the -course to pursue both in fair weather and foul, so those who are called -upon to advise the King must always be guided by a spirit of justice." - - -Brunetto Latini, in his _Trsor des Sciences_, 1260, writes: - -"The sailors navigate the seas guided by the two stars called the -tramontanes, and each of the two parts of the lodestone directs the end -of the needle to the star to which that part itself turns." - -Brunetto Latini (1230-1294) was a man of great eminence in the -thirteenth century; Dante was among his pupils at Florence. For -political reasons, he removed to Paris, where he wrote his _Trsor_ and -also his _Tesoretto_. He visited Roger Bacon at Oxford about 1260. - - -In his treatise _De Contemplatione_, begun in 1272, Raymond Lully -writes: - -"As the needle, after having touched the lodestone, turns to the north, -so the mariner's needle (_acus nautica_) directs them over the sea." - -Lully was born at Palma in the Island of Majorca in 1236; he joined the -Third Order of St. Francis, dying in 1315. - - -Ristoro d'Arezzo, in his _Libro della Composizione del Mundo_, written -in 1282, has the following: - -"Besides this, there is the needle which guides the mariner, and which -is itself directed by the star called the tramontane."[6] - - -The following metrical translation of a poem by Guido Guinicelli, an -Italian priest, 1276, is from the pen of Dr. Park Benjamin, of New York: - - In what strange regions 'neath the polar star - May the great hills of massy lodestone rise, - Virtue imparting to the ambient air - To draw the stubborn iron; while afar - From that same stone, the hidden virtue flies - To turn the quivering needle to the Bear - In splendor blazing in the Northern skies. - -The above extracts show that the directive property of the magnetic -needle was well known in England, France, Germany, Spain and Italy in -the thirteenth century. In the passage from Neckam, the _acum jaculo -superpositam_ has been construed by some to mean a form of pivoted -needle, while in the letter of Peregrinus, 1269, the double pivoted form -is clearly described. - - - - - Footnotes - - -[1]With very few exceptions all the works referred to in this notice - will be found in the Wheeler Collection in the Library of the - American Institute of Electrical Engineers, New York. - -[2]It is probable that Flavio Gioja, an Italian pilot, some fifty years - later, added the compass-card and attached it to the magnet. - -[3]Annali di Matematica Pura ed Applicata, 1865. - -[4]A terrella, or earthkin. - -[5]The Chronicles and Memoirs of Great Britain and Ireland during the - Middle Ages, by Thomas Wright (1863). - -[6]The pole-star was thus named in the south of France and the north of - Italy because seen beyond the mountains (the Alps). - - - - - Transcriber's Notes - - ---Retained publication and copyright information from the original; this - eBook is public-domain in the U.S. - ---Silently corrected a few palpable typographical errors. - ---In the text versions, enclosed italicized text in _underscore_. - - - - - - - -End of the Project Gutenberg EBook of The Letter of Petrus Peregrinus on the -Magnet, A.D. 1269, by Petrus Peregrinus - -*** END OF THIS PROJECT GUTENBERG EBOOK LETTER OF PETRUS PEREGRINUS ON MAGNET *** - -***** This file should be named 50524-8.txt or 50524-8.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/0/5/2/50524/ - -Produced by deaurider, Stephen Hutcheson, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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} -p.book { margin-left:2em; text-indent:-2em; } -p.review { margin-left:2em; text-indent:-2em; font-size:80%; } -p.pcap { margin-left:0em; text-indent:0em; text-align:center; margin-top:0em; font-weight:bold; font-size:90%; } -p.pcapc { margin-left:4.7em; text-indent:0em; text-align:justify; } -span.pn { display:inline-block; width:4.7em; text-align:left; margin-left:0; text-indent:0; } -div.sidenote { max-width:50%; float:left; clear:left; - - margin-bottom:1em; font-weight:bold; font-size:90%; } - - -</style> -</head> -<body> - - -<pre> - -The Project Gutenberg EBook of The Letter of Petrus Peregrinus on the -Magnet, A.D. 1269, by Petrus Peregrinus - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The Letter of Petrus Peregrinus on the Magnet, A.D. 1269 - -Author: Petrus Peregrinus - -Translator: Brother Arnold - -Release Date: November 21, 2015 [EBook #50524] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK LETTER OF PETRUS PEREGRINUS ON MAGNET *** - - - - -Produced by deaurider, Stephen Hutcheson, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - -</pre> - -<div id="cover" class="img"> -<img id="coverpage" src="images/cover.jpg" alt="Letter of Petrus Peregrinus on the Magnet A.D. 1269" width="500" height="699" /> -</div> -<div class="box"> -<h1><span class="small">THE LETTER OF -<br />PETRUS</span> -<br />PEREGRINUS -<br /><span class="smaller">ON THE MAGNET, A.D. 1269</span></h1> -<p class="tbcenter"><span class="smaller">TRANSLATED BY</span> -<br />BROTHER ARNOLD, M.Sc. -<br /><span class="smaller">PRINCIPAL OF LA SALLE INSTITUTE, TROY -<br />WITH</span> -<br />INTRODUCTORY NOTICE -<br /><span class="smaller">BY</span> -<br />BROTHER POTAMIAN, D.Sc. -<br /><span class="smaller">PROFESSOR OF PHYSICS IN MANHATTAN -<br />COLLEGE, NEW YORK</span></p> -<p class="tbcenter"><span class="small">NEW YORK -<br />McGRAW PUBLISHING COMPANY -<br />MCMIV</span></p> -</div> -<div class="pb" id="Page_vi">vi</div> -<p class="center small">Copyright, 1904, by -<br /><span class="sc">McGraw Publishing Company</span></p> -<div class="pb" id="Page_vii">vii</div> -<h2 id="c1">INTRODUCTORY</h2> -<p>The magnetic lore of classic antiquity was -scanty indeed, being limited to the attraction -which the lodestone manifests -for iron. Lucretius (99-55 B. C.), however, in -his poetical dissertation on the magnet, contained -in <i>De Rerum Natura</i>, Book VI.<a class="fn" id="fr_1" href="#fn_1">[1]</a> recognizes magnetic -repulsion, magnetic induction, and to some -extent the magnetic field with its lines of force, -for in verse 1040 he writes:</p> -<div class="verse"> -<p class="t0">Oft from the magnet, too, the steel recedes,</p> -<p class="t0">Repelled by turns and re-attracted close.</p> -</div> -<p>And in verse 1085:</p> -<div class="verse"> -<p class="t0">Its viewless, potent virtues men surprise;</p> -<p class="t0">Its strange effects, they view with wond’ring eyes</p> -<div class="pb" id="Page_viii">viii</div> -<p class="t0">When without aid of hinges, links or springs</p> -<p class="t0">A pendant chain we hold of steely rings</p> -<p class="t0">Dropt from the stone—the stone the binding source—</p> -<p class="t0">Ring cleaves to ring and owns magnetic force:</p> -<p class="t0">Those held above, the ones below maintain,</p> -<p class="t0">Circle ’neath circle downward draws in vain</p> -<p class="t0">Whilst free in air disports the oscillating chain.</p> -</div> -<p>The poet Claudian (365-408 A. D.) wrote a -short idyll on the attractive virtue of the lodestone -and its symbolism; St. Augustine (354-430), -in his work <i>De Civitate Dei</i>, records the -fact that a lodestone, held under a silver plate, -draws after it a scrap of iron lying on the plate. -Abbot Neckam, the Augustinian (1157-1217), -distinguishes between the properties of the two -ends of the lodestone, and gives in his <i>De Utensilibus</i>, -what is perhaps the earliest reference to -the mariner’s compass that we have. Albertus -Magnus, the Dominican (1193-1280), in his -treatise, <i>De Mineralibus</i>, enumerates different kinds -of natural magnets and states some of the properties -commonly attributed to them; the minstrel, -Guyot de Provins, in a famous satirical poem, -written about 1208, refers to the directive quality -<span class="pb" id="Page_ix">ix</span> -of the lodestone and its use in navigation, as -do also Cardinal de Vitry in his <i>Historia Orientalis</i> -(1215-1220); Brunetto Latini, poet, orator -and philosopher, in his <i>Trésor des Sciences</i>, a veritable -library, written in Paris in 1260; Raymond -Lully, the Enlightened Doctor, in his -treatise, <i>De Contemplatione</i>, begun in 1272, and -Guido Guinicelli, the poet-priest of Bologna, -who died in 1276.</p> -<p>The authors of these learned works were too -busy with the pen to find time to devote to the -close and prolonged study of natural phenomena -necessary for fruitful discovery, and so had to content -themselves with recording and discussing in -their tomes the scientific knowledge of their age -without making any notable additions to it.</p> -<p>But this was not the case with such contemporaries -of theirs as Roger Bacon, the Franciscan, -and his Gallic friend, Pierre de Maricourt, -commonly called Petrus Peregrinus, the subject -of the present notice, a man of academic culture -and of a practical rather than speculative turn of -mind. Of the early years of Peregrinus nothing -<span class="pb" id="Page_x">x</span> -is known save that he studied probably at the University -of Paris, and that he graduated with the highest -scholastic honors. He owes his surname to -the village of Maricourt, in Picardy, and the appellation -Peregrinus, or Pilgrim, to his having -visited the Holy Land as a member of one of the -crusading expeditions of the time.</p> -<p>In 1269 we find him in the engineering corps -of the French army then besieging Lucera, in -Southern Italy, which had revolted from the authority -of its French master, Charles of Anjou. To -Peregrinus was assigned the work of fortifying -the camp and laying mines as well as of constructing -engines for projecting stones and fire-balls -into the beleaguered city.</p> -<p>It was in the midst of such warlike preoccupations -that the idea seems to have occurred to -him of devising a piece of mechanism to keep -the astronomical sphere of Archimedes in uniform -rotation for a definite time. In the course -of his work over the new motor, Peregrinus was -gradually led to consider the more fascinating -problem of perpetual motion itself with the result -<span class="pb" id="Page_xi">xi</span> -that he showed, at least diagrammatically, and to -his own evident satisfaction, how a wheel might -be driven round forever by the power of magnetic -attraction.</p> -<p>Elated over his imaginary success, Peregrinus -hastened to inform a friend of his at home; and -that his friend might the more readily comprehend -the mechanism of the motor and the functions -of its parts, he proceeds to set forth in a -methodical manner all the properties of the lodestone, -most of which he himself had discovered. -It is a fortunate circumstance that this Picard -friend of his was not a man learned in the sciences, -otherwise we would probably never have -had the remarkable exposition which Peregrinus -gives of the phenomena and laws of magnetism. -This letter of 3,500 words is the first great landmark -in the domain of magnetic philosophy, the -next being Gilbert’s <i>De Magnete</i>, in 1600.</p> -<p>The letter was addressed from the trenches -at Lucera, Southern Italy, in August, 1269, to Sigerus -de Foucaucourt, his “amicorum intimus,” -the dearest of friends. A more enlightened friend, -<span class="pb" id="Page_xii">xii</span> -however, than the knight of Foucaucourt was -Roger Bacon, who held Peregrinus in the very -highest esteem, as the following glowing testimony -shows: “There are but two perfect mathematicians,” -wrote the English monk, “John of -London and Petrus de Maharne-Curia, a Picard.” -Further on in his <i>Opus Tertium</i>, Bacon thus appraises -the merits of the Picard: “I know of -only one person who deserves praise for his work -in experimental philosophy, for he does not care -for the discourses of men and their wordy warfare, -but quietly and diligently pursues the works -of wisdom. Therefore, what others grope after -blindly, as bats in the evening twilight, this man -contemplates in all their brilliancy because he is -a master of experiment. Hence, he knows all -natural science whether pertaining to medicine -and alchemy, or to matters celestial and terrestrial. -He has worked diligently in the smelting -of ores as also in the working of minerals; he is -thoroughly acquainted with all sorts of arms and -implements used in military service and in hunting, -besides which he is skilled in agriculture and -<span class="pb" id="Page_xiii">xiii</span> -in the measurement of lands. It is impossible to -write a useful or correct treatise in experimental -philosophy without mentioning this man’s name. -Moreover, he pursues knowledge for its own sake; -for if he wished to obtain royal favor, he could -easily find sovereigns who would honor and enrich -him.”</p> -<p>This last statement is worthy of the best utterances -of the twentieth century. Say what they -will, the most ardent pleaders of our day for original -work and laboratory methods cannot surpass -the Franciscan monk of the thirteenth century -in his denunciation of mere book learning -or in his advocacy of experiment and research, -while in Peregrinus, the mediævalist, they have -Bacon’s impersonation of what a student of science -ought to be. Peregrinus was a hard worker, -nor a mere theorizer, preferring, Procrustean-like, -to make theory fit the facts rather than facts -the theory; he was a brilliant discoverer who -knew at the same time how to use his discoveries -for the benefit of mankind; he was a pioneer of -science and a leader in the progress of the world.</p> -<div class="pb" id="Page_xiv">xiv</div> -<p>An analysis of the “Epistola” shows that</p> -<p>(<i>a</i>) Peregrinus was the first to assign a definite -position to the poles of a lodestone, and to -give directions for determining which is north and -which south;</p> -<p>(<i>b</i>) He proved that unlike poles attract each -other, and that similar ones repel;</p> -<p>(<i>c</i>) He established by experiment that every -fragment of a lodestone, however small, is a complete -magnet, thus anticipating one of our fundamental -laboratory illustrations of the molecular -theory;</p> -<p>(<i>d</i>) He recognized that a pole of a magnet -may neutralize a weaker one of the same name, -and even reverse its polarity;</p> -<p>(<i>e</i>) He was the first to pivot a magnetized -needle and surround it with a graduated circle, -Figs. <a href="#fig2">2</a> and <a href="#fig3">3</a>.<a class="fn" id="fr_2" href="#fn_2">[2]</a></p> -<p>(<i>f</i>) He determined the position of an object -by its magnetic bearing as done to-day in compass -surveying; and</p> -<div class="pb" id="Page_xv">xv</div> -<p>(<i>g</i>) He introduced into his perpetual motion -machine, <a href="#fig4">Fig. 4</a>, the idea of a magnetic motor, -a clever idea, indeed, for a thirteenth century engineer.</p> -<p>This rapid summary will serve to show that -the letter of Peregrinus is one of great interest -in physics as well as in navigation and geodesy. -For nearly three centuries, it lay unnoticed among -the libraries of Europe, but it did not escape Gilbert, -who makes frequent mention of it in his -<i>De Magnete</i>, 1600; nor the illustrious Jesuit writers, -Cabæus, who refers to it in his <i>Philosophia -Magnetica</i>, 1629, and Kircher, who quotes from -it in his <i>De Arte Magnetica</i>, 1641; it was well -known to Jean Taisnier, the Belgian plagiarist, -who transferred a great part of it verbatim to the -pages of his <i>De Natura Magnetis</i>, 1562, without -a word of acknowledgment. By this piece of -fraud, Taisnier acquired considerable celebrity, -a fact that goes to show the meritorious character -of the work which he unscrupulously -copied.</p> -<p>This memorable letter is divided into two -<span class="pb" id="Page_xvi">xvi</span> -parts: the first contains ten chapters on the general -properties of the lodestone; the second has -but three chapters, and shows how the author proposed -to use a lodestone for the purpose of producing -continuous rotation.</p> -<p>There are many manuscript copies of the letter -in European libraries: the Bodleian has six; -the Vatican, two; Trinity College, Dublin, one; -the Bibliothèque Nationale, Paris, one; Leyden, -Geneva and Turin, one each. The Leyden MS. -has acquired special notoriety from a passage which -appears near the end of it in which reference is -made to magnetic declination and its value given: -but Prof. W. Wenckebach, of The Hague, has -shown<a class="fn" id="fr_3" href="#fn_3">[3]</a> that the lines are spurious, having been interpolated -in the manuscript in the early part of -the sixteenth century.</p> -<p>The Leyden manuscript has also led some -writers to believe in a fictitious author of the letter, -one Peter Adsiger, or Petrus Adsigerus. As -said above, Sigerus was the name of his countryman, -to whom Peregrinus addressed his letter, -<span class="pb" id="Page_xvii">xvii</span> -the <i>Epistola ad Sigerum</i>, from the trenches at Lucera, -in August, 1269.</p> -<p>Magnetic declination was unknown to Peregrinus, -else he would not have written the following -words: “Wherever a man may be, he finds -the lodestone pointing to the heavens in accordance -with the position of the meridian” (Chapter X). Of course, the geographical meridian is the -one here meant, as the necessity of a distinct -magnetic meridian had not yet occurred to any -one.</p> -<p>Nor was this important magnetic element -known to Columbus when he sailed from the -shores of the Old World in 1492 as appears from -the surprise with which he noticed the deviation -of the needle from North as well as from the -consternation of his pilots. Columbus has the -unquestionable merit of being the first to observe -and record the change of declination with change -of place.</p> -<p>The first printed edition of the Epistola, now -very rare, was prepared by Achilles Gasser, a physician -of Lindau, a man well versed in mathematics, -<span class="pb" id="Page_xviii">xviii</span> -astronomy, history and philosophy. The -work was printed in Augsburg in 1558. A copy -of this early print is among the treasures of the -Wheeler collection in the library of the American -Institute of Electrical Engineers, New York. -It was from this text that the translation which -follows was made.</p> -<p>Besides the Latin edition of Gasser, 1558, -there is also that of Libri in his <i>Histoire des Sciences -Mathématiques</i>, 1838; of Bertelli, 1868, and -Hellmann, 1898. Bertelli’s is a learned and exhaustive -work in which the Barnabite monk, sometimes -called by mistake, Barnabita, instead of Bertelli, -collates and compares the readings of the -two Vatican codices with other texts, adding copious -references and explanatory notes. It appeared -in the <i>Bulletino di Bibliografia e di Storia delle Scienze -Matematiche e Fisiche</i> for 1868.</p> -<p>Of translations, we have that which Richard -Eden made from Taisnier’s pirated extracts, the -first dated edition appearing in 1579. Cavallo’s -<i>Treatise on Magnetism</i>, 1800, also contains some -of the more remarkable passages. The only complete -<span class="pb" id="Page_xix">xix</span> -English translation that we have, appeared -in 1902 from the scholarly pen of Prof. Silvanus -P. Thompson, of London. It is an <i>édition de luxe</i> -beautifully rubricated, but limited to 250 copies. -The translation was based on the texts of Gasser -and Hellmann, amended by reference to a manuscript -in the author’s possession, dated 1391. -We are informed that Mr. Fleury P. Mottelay, -of New York, the learned translator of Gilbert’s -<i>De Magnete</i>, possesses a manuscript version by -Prof. Peirce, of Harvard, of the Paris codex, of -which he made a careful study in an endeavor to -decipher the illegible parts.</p> -<div class="pb" id="Page_1">1</div> -<h2 id="c2">PART I</h2> -<div class="pb" id="Page_3">3</div> -<h2 id="c3">THE LETTER OF -<br />PEREGRINUS</h2> -<h3>PART I -<br />CHAPTER I -<br />PURPOSE OF THIS WORK</h3> -<p><span class="sc">Dearest of Friends</span>:</p> -<p>At your earnest request, I will now make -known to you, in an unpolished narrative, -the undoubted though hidden virtue of the lodestone, -concerning which philosophers up to the -present time give us no information, because it -is characteristic of good things to be hidden in -darkness until they are brought to light by application -to public utility. Out of affection for -you, I will write in a simple style about things -entirely unknown to the ordinary individual. -Nevertheless I will speak only of the manifest -properties of the lodestone, because this tract will -form part of a work on the construction of philosophical -instruments. The disclosing of the -<span class="pb" id="Page_4">4</span> -hidden properties of this stone is like the art of -the sculptor by which he brings figures and seals -into existence. Although I may call the matters -about which you inquire evident and of inestimable -value, they are considered by common -folk to be illusions and mere creations of the imagination. -But the things that are hidden from -the multitude will become clear to astrologers -and students of nature, and will constitute their -delight, as they will also be of great help to those -that are old and more learned.</p> -<h3>CHAPTER II -<br />QUALIFICATIONS OF THE EXPERIMENTER</h3> -<p>You must know, my dear friend, that whoever -wishes to experiment, should be acquainted -with the nature of things, and should -not be ignorant of the motion of the celestial -bodies. He must also be skilful in manipulation -in order that, by means of this stone, he may produce -these marvelous effects. Through his own -industry he can, to some extent, indeed, correct -<span class="pb" id="Page_5">5</span> -the errors that a mathematician would inevitably -make if he were lacking in dexterity. Besides, -in such occult experimentation, great skill is required, -for very frequently without it the desired -result cannot be obtained, because there are many -things in the domain of reason which demand -this manual dexterity.</p> -<h3>CHAPTER III -<br />CHARACTERISTICS OF A GOOD LODESTONE</h3> -<p>The lodestone selected must be distinguished -by four marks—its color, homogeneity, -weight and strength. Its color should be iron-like, -pale, slightly bluish or indigo, just as polished -iron becomes when exposed to the corroding -atmosphere. I have never yet seen a stone -of such description which did not produce wonderful -effects. Such stones are found most frequently -in northern countries, as is attested by -sailors who frequent places on the northern seas, -notably in Normandy, Flanders and Picardy. -This stone should also be of homogeneous material; -<span class="pb" id="Page_6">6</span> -one having reddish spots and small holes -in it should not be chosen; yet a lodestone is -hardly ever found entirely free from such blemishes. -On account of uniformity in its composition -and the compactness of its innermost parts, -such a stone is heavy and therefore more valuable. -Its strength is known by its vigorous attraction -for a large mass of iron; further on I -will explain the nature of this attraction. If you -chance to see a stone with all these characteristics, -secure it if you can.</p> -<h3>CHAPTER IV -<br />HOW TO DISTINGUISH THE POLES OF A LODESTONE</h3> -<p>I wish to inform you that this stone bears in -itself the likeness of the heavens, as I will -now clearly demonstrate. There are in the heavens -two points more important than all others, -because on them, as on pivots, the celestial sphere -revolves: these points are called, one the arctic -or north pole, the other the antarctic or south -pole. Similarly you must fully realize that in -<span class="pb" id="Page_7">7</span> -this stone there are two points styled respectively -the north pole and the south pole. If you -are very careful, you can discover these two -points in a general way. One method for doing -so is the following: With an instrument with -which crystals and other stones are rounded let -a lodestone be made into a globe and then polished. -A needle or an elongated piece of iron -is then placed on top of the lodestone and a line -is drawn in the direction of the needle or iron, -thus dividing the stone into two equal parts. -The needle is next placed on another part of the -stone and a second median line drawn. If desired, -this operation may be performed on many -different parts, and undoubtedly all these lines -will meet in two points just as all meridian or -azimuth circles meet in the two opposite poles -of the globe. One of these is the north pole, -the other the south pole. Proof of this will be -found in a subsequent chapter of this tract.</p> -<p>A second method for determining these important -points is this: Note the place on the -above-mentioned spherical lodestone where the -point of the needle clings most frequently and -<span class="pb" id="Page_8">8</span> -most strongly; for this will be one of the poles -as discovered by the previous method. In order -to determine this point exactly, break off a small -piece of the needle or iron so as to obtain a fragment -about the length of two fingernails; then -put it on the spot which was found to be the -pole by the former operation. If the fragment -stands perpendicular to the stone, then that is, -unquestionably, the pole sought; if not, then -move the iron fragment about until it becomes -so; mark this point carefully; on the opposite -end another point may be found in a similar manner. -If all this has been done rightly, and if -the stone is homogeneous throughout and a -choice specimen, these two points will be diametrically -opposite, like the poles of a sphere.</p> -<h3>CHAPTER V -<br />HOW TO DISCOVER THE POLES OF A LODESTONE AND HOW TO TELL WHICH IS NORTH AND WHICH SOUTH</h3> -<p>The poles of a lodestone having been located -in a general way, you will determine which -is north and which south in the following manner: -<span class="pb" id="Page_9">9</span> -Take a wooden vessel rounded like a platter -or dish, and in it place the stone in such a -way that the two poles will be equidistant from -the edge of the vessel; then place the dish in -another and larger vessel full of water, so that -the stone in the first-mentioned dish may be like -a sailor in a boat. The second vessel should be -of considerable size so that the first may resemble -a ship floating in a river or on the sea. I insist -upon the larger size of the second vessel in order -that the natural tendency of the lodestone may -not be impeded by contact of one vessel against -the sides of the other. When the stone has been -thus placed, it will turn the dish round until the -north pole lies in the direction of the north pole -of the heavens, and the south pole of the stone -points to the south pole of the heavens. Even -if the stone be moved a thousand times away from -its position, it will return thereto a thousand -times, as by natural instinct. Since the north -and south parts of the heavens are known, these -same points will then be easily recognized in -the stone because each part of the lodestone will -turn to the corresponding one of the heavens.</p> -<div class="pb" id="Page_10">10</div> -<h3>CHAPTER VI -<br />HOW ONE LODESTONE ATTRACTS ANOTHER</h3> -<p>When you have discovered the north and -the south pole in your lodestone, mark -them both carefully, so that by means of these -indentations they may be distinguished whenever -necessary. Should you wish to see how one lodestone -attracts another, then, with two lodestones -selected and prepared as mentioned in the preceding -chapter, proceed as follows: Place one -in its dish that it may float about as a sailor in -a skiff, and let its poles which have already been -determined be equidistant from the horizon, i. e., -from the edge of the vessel. Taking the other -stone in your hand, approach its north pole to -the south pole of the lodestone floating in the -vessel; the latter will follow the stone in your -hand as if longing to cling to it. If, conversely, -you bring the south end of the lodestone in your -hand toward the north end of the floating lodestone, -the same phenomenon will occur; namely, -the floating lodestone will follow the one in your -hand. Know then that this is the law: the north -<span class="pb" id="Page_11">11</span> -pole of one lodestone attracts the south pole of -another, while the south pole attracts the north. -Should you proceed otherwise and bring the north -pole of one near the north pole of another, the -one you hold in your hand will seem to put the -floating one to flight. If the south pole of one -is brought near the south pole of another, the -same will happen. This is because the north -pole of one seeks the south pole of the other, -and therefore repels the north pole. A proof of -this is that finally the north pole becomes united -with the south pole. Likewise if the south pole -is stretched out towards the south pole of the -floating lodestone, you will observe the latter to -be repelled, which does not occur, as said before, -when the north pole is extended towards the -south. Hence the silliness of certain persons is -manifest, who claim that just as scammony attracts -jaundice on account of a similarity between -them, so one lodestone attracts another even more -strongly than it does iron, a fact which they suppose -to be false although really true as shown by -experiment.</p> -<div class="pb" id="Page_12">12</div> -<h3>CHAPTER VII -<br />HOW IRON TOUCHED BY A LODESTONE TURNS TOWARDS THE POLES OF THE WORLD</h3> -<p>It is well known to all who have made the -experiment, that when an elongated piece -of iron has touched a lodestone and is then fastened -to a light block of wood or to a straw and -made float on water, one end will turn to the -star which has been called the Sailor’s star because -it is near the pole; the truth is, however, -that it does not point to the star but to the pole -itself. A proof of this will be furnished in a -following chapter. The other end of the iron -will point in an opposite direction. But as to -which end of the iron will turn towards the -north and which to the south, you will observe -that that part of the iron which has touched the -south pole of the lodestone will point to the north -and conversely, that part which had been in contact -with the north pole will turn to the south. -Though this appears marvelous to the uninitiated, -yet it is known with certainty to those who -have tried the experiment.</p> -<div class="pb" id="Page_13">13</div> -<h3>CHAPTER VIII -<br />HOW A LODESTONE ATTRACTS IRON</h3> -<p>If you wish the stone, according to its natural -desire, to attract iron, proceed as follows: -Mark the north end of the iron and towards -this end approach the south pole of the stone, -when it will be found to follow the latter. Or, -on the contrary, to the south part of the iron -present the north pole of the stone and the latter -will attract it without any difficulty. Should -you, however, do the opposite, namely, if you -bring the north end of the stone towards the -north pole of the iron, you will notice the iron -turn round until its south pole unites with the -north end of the lodestone. The same thing -will occur when the south end of the lodestone -is brought near the south pole of the iron. -Should force be exerted at either pole, so that -when the south pole of the iron is made touch -the south end of the stone, then the virtue in -the iron will be easily altered in such a manner -that what was before the south end will now -become the north and conversely. The cause is -<span class="pb" id="Page_14">14</span> -that the last impression acts, confounds, or counteracts -and alters the force of the original movement.</p> -<h3>CHAPTER IX -<br />WHY THE NORTH POLE OF ONE LODESTONE ATTRACTS THE SOUTH POLE OF ANOTHER AND VICE VERSA</h3> -<p>As already stated, the north pole of one lodestone -attracts the south pole of another -and conversely; in this case the virtue of the -stronger becomes active, whilst that of the weaker -becomes obedient or passive. I consider the following -to be the cause of this phenomenon: the -active agent requires a passive subject, not merely -to be joined to it, but also to be united with it, -so that the two make but one by nature. In the -case of this wonderful lodestone this may be -shown in the following manner: Take a lodestone -which you may call <i>A D</i>, in which <i>A</i> is -the north pole and <i>D</i> the south; cut this stone -into two parts, so that you may have two distinct -<span class="pb" id="Page_15">15</span> -stones; place the stone having the pole <i>A</i> so -that it may float on water and you will observe -that <i>A</i> turns towards the north as before; the -breaking did not destroy the properties of the -parts of the stone, since it is homogeneous; -hence it follows that the part of the stone at -the point of fracture, which may be marked <i>B</i>, -must be a south pole; this broken part of which -we are now speaking may be called <i>A B</i>. The -other, which contains <i>D</i>, should then be placed -so as to float on water, when you will see <i>D</i> -point towards the south because it is a south -pole; but the other end at the point of fracture, -lettered <i>C</i>, will be a north pole; this stone may -now be named <i>C D</i>. If we consider the first -stone as the active agent, then the second, or -<i>C D</i>, will be the passive subject. You will also -notice that the ends of the two stones which -before their separation were together, after -breaking will become one a north pole and the -other a south pole. If now these same broken -portions are brought near each other, one will -attract the other, so that they will again be -<span class="pb" id="Page_16">16</span> -joined at the points <i>B</i> and <i>C</i>, where the fracture -occurred. Thus, by natural instinct, one single -stone will be formed as before. This may be -demonstrated fully by cementing the parts together, -when the same effects will be produced -as before the stone was broken. As you will -perceive from this experiment, the active agent -desires to become one with the passive subject -because of the similarity that exists between -them. Hence <i>C</i>, being a north pole, must be -brought close to <i>B</i>, so that the agent and its -subject may form one and the same straight line -in the order <i>A B</i>, <i>C D</i> and <i>B</i> and <i>C</i> being at -the same point. In this union the identity -of the extreme parts is retained and preserved -just as they were at first; for <i>A</i> is the north pole -in the entire line as it was in the divided one; -so also <i>D</i> is the south pole as it was in the divided -passive subject, but <i>B</i> and <i>C</i> have been -made effectually into one. In the same way it -happens that if <i>A</i> be joined to <i>D</i> so as to make -the two lines one, in virtue of this union due to -attraction in the order <i>C D A B</i>, then <i>A</i> and <i>D</i> -<span class="pb" id="Page_17">17</span> -will constitute but one point, the identity of the -extreme parts will remain unchanged just as they -were before being brought together, for <i>C</i> is a -north pole and <i>B</i> a south, as during their separation. -If you proceed in a different fashion, -this identity or similarity of parts will not be -preserved; for you will perceive that if <i>C</i>, a -north pole, be joined to <i>A</i>, a north pole, contrary -to the demonstrated truth, and from these -two lines a single one, <i>B A C D</i>, is formed, as -<i>D</i> was a south pole before the parts were united, -it is then necessary that the other extremity -should be a north pole, and as <i>B</i> is a south pole, -the identity of the parts of the former similarity -is destroyed. If you make <i>B</i> the south pole as -it was before they united, then <i>D</i> must become -north, though it was south in the original stone; -in this way neither the identity nor similarity -of parts is preserved. It is becoming that when -the two are united into one, they should bear -the same likeness as the agent, otherwise nature -would be called upon to do what is impossible. -The same incongruity would occur if you were -<span class="pb" id="Page_18">18</span> -to join <i>B</i> with <i>D</i> so as to make the line <i>A B D C</i>, -as is plain to any person who reflects a moment. -Nature, therefore, aims at being and also at acting -in the best manner possible; it selects the -former motion and order rather than the second -because the identity is better preserved. From -all this it is evident why the north pole attracts -the south and conversely, and also why the south -pole does not attract the south pole and the -north pole does not attract the north.</p> -<h3>CHAPTER X -<br />AN INQUIRY INTO THE CAUSE OF THE NATURAL VIRTUE OF THE LODESTONE</h3> -<p>Certain persons who were but poor investigators -of nature held the opinion that -the force with which a lodestone draws iron, is -found in the mineral veins themselves from which -the stone is obtained; whence they claim that -the iron turns towards the poles of the earth, only -because of the numerous iron mines found there. -But such persons are ignorant of the fact that in -<span class="pb" id="Page_19">19</span> -many different parts of the globe the lodestone -is found; from which it would follow that the iron -needle should turn in different directions according -to the locality; but this is contrary to experience. -Secondly, these individuals do not seem to -know that the places under the poles are uninhabitable -because there one-half the year is day -and the other half night. Hence it is most silly -to imagine that the lodestone should come to us -from such places. Since the lodestone points to the -south as well as to the north, it is evident from -the foregoing chapters that we must conclude -that not only from the north pole but also from -the south pole rather than from the veins of the -mines virtue flows into the poles of the lodestone. -This follows from the consideration that wherever -a man may be, he finds the stone pointing -to the heavens in accordance with the position -of the meridian; but all meridians meet in the -poles of the world; hence it is manifest that -from the poles of the world, the poles of the -lodestone receive their virtue. Another necessary -consequence of this is that the needle does -<span class="pb" id="Page_20">20</span> -not point to the pole star, since the meridians -do not intersect in that star but in the poles of -the world. In every region, the pole star is always -found outside the meridian except twice in -each complete revolution of the heavens. From -all these considerations, it is clear that the poles -of the lodestone derive their virtue from the -poles of the heavens. As regards the other parts -of the stone, the right conclusion is, that they -obtain their virtue from the other parts of the -heavens, so that we may infer that not only -the poles of the stone receive their virtue and -influence from the poles of the world, but likewise -also the other parts, or the entire stone from -the entire heavens. You may test this in the -following manner: A round lodestone on which -the poles are marked is placed on two sharp styles -as pivots having one pivot under each pole so -that the lodestone may easily revolve on these -pivots. Having done this, make sure that it is -equally balanced and that it turns smoothly on -the pivots. Repeat this several times at different -hours of the day and always with the utmost -<span class="pb" id="Page_21">21</span> -care. Then place the stone with its axis in -the meridian, the poles resting on the pivots. -Let it be moved after the manner of bracelets so -that the elevation and depression of the poles may -equal the elevation and depressions of the poles -of the heavens of the place in which you are experimenting. -If now the stone be moved according -to the motion of the heavens, you will -be delighted in having discovered such a wonderful -secret; but if not, ascribe the failure to -your own lack of skill rather than to a defect in -nature. Moreover, in this position I consider -the strength of the lodestone to be best preserved. -When it is placed differently, i. e., not in the meridian, -I think its virtue is weakened or obscured -rather than maintained. With such an instrument -you will need no timepiece, for by it you can know -the ascendant at any hour you please, as well as -all other dispositions of the heavens which are -sought for by astrologers.</p> -<div class="pb" id="Page_23">23</div> -<h2 id="c4">PART II</h2> -<div class="pb" id="Page_25">25</div> -<h3>PART II -<br />CHAPTER I -<br />THE CONSTRUCTION OF AN INSTRUMENT FOR MEASURING THE AZIMUTH OF THE SUN THE MOON OR ANY STAR ON THE HORIZON</h3> -<p>Having fully examined all the properties -of the lodestone and the phenomena connected -therewith, let us now come to those instruments -which depend for their operation on -the knowledge of those facts. Take a rounded -lodestone,<a class="fn" id="fr_4" href="#fn_4">[4]</a> and after determining its poles in the -manner already mentioned, file its two sides so -that it becomes elongated at its poles and occupies -less space. The lodestone prepared in this -wise is then enclosed within two capsules after -the fashion of a mirror. Let these capsules be -so joined together that they cannot be separated -<span class="pb" id="Page_26">26</span> -and that water cannot enter; they should -be made of light wood and fastened with cement -suited to the purpose. Having done this, place -them in a large vessel of water on the edges of -which the two parts of the world, i. e., the -north and south points, have been found and -marked. These points may be united by a -thread stretched across from north to south. -Then float the capsules and place a smooth strip -of wood over them in the manner of a diameter. -Move the strip until it is equally distant -from the meridian-line, previously determined -and marked by a thread, or else until it coincides -therewith. Then mark a line on the capsules -according to the position of the strip, and -this will indicate forever the meridian of that -place. Let this line be divided at its middle by -another cutting it at right angles, which will -give the east and west line; thus the four cardinal -points will be determined and indicated on -the edge of the capsules. Each quarter is to be -subdivided into 90 parts, making 360 in the circumference -of the capsules. Engrave these divisions -<span class="pb" id="Page_27">27</span> -on them as usually done on the back of -an astrolabe. On the top or edge of the capsules -thus marked place a thin ruler like the -pointer on the back of the astrolabe; instead of -the sights attach two perpendicular pins, one at -each end. If, therefore, you desire to take the -azimuth of the sun, place the capsules in water -and let them move freely until they come to -rest in their natural position. Hold them firmly -in one hand, while with the other you move the -ruler until the shadow of the pins falls along the -length of the ruler; then the end of the ruler -which is towards the sun will indicate the azimuth -of the sun. Should it be windy, let the -capsules be covered with a suitable vessel until -they have taken their position north and south. -The same method, namely, by sighting, may be -followed at night for determining the azimuth -of the moon and stars; move the ruler until the -ends of the pins are in the same line with the -moon or star; the end of the ruler will then indicate -the azimuth just as in the case of the sun. -By means of the azimuth may then be determined -<span class="pb" id="Page_28">28</span> -the hour of the day, the ascendant, and -all those other things usually determined by the -astrolabe. A form of the instrument is shown -in the following figure.</p> -<div class="img" id="ill1"> -<img id="fig1" src="images/i_p28.jpg" alt="FIG. 1.—AZIMUTH COMPASS" width="500" height="492" /> -<p class="pcap">FIG. 1.—AZIMUTH COMPASS</p> -</div> -<h3>CHAPTER II -<br />THE CONSTRUCTION OF A BETTER INSTRUMENT FOR THE SAME PURPOSE</h3> -<p>In this chapter I will describe the construction -of a better and more efficient instrument. -Select a vessel of wood, brass or any solid material -you like, circular in shape, moderate in -<span class="pb" id="Page_29">29</span> -size, shallow but of sufficient width, with a cover -of some transparent substance, such as glass or -crystal; it would be even better to have both -the vessel and the cover transparent. At the -centre of this vessel fasten a thin axis of brass -or silver, having its extremities in the cover -above and the vessel below. At the middle of -this axis let there be two apertures at right angles -to each other; through one of them pass -an iron stylus or needle, through the other a silver -or brass needle crossing the iron one at right -angles. Divide the cover first into four parts -and subdivide these into 90 parts, as was mentioned -in describing the former instrument. -Mark the parts north, south, east and west. Add -thereto a ruler of transparent material with pins -at each end. After this bring either the north -or the south pole of a lodestone near the cover -so that the needle may be attracted and receive -its virtue from the lodestone. Then turn the -vessel until the needle stands in the north and -south line already marked on the instrument; -after which turn the ruler towards the sun if -<span class="pb" id="Page_30">30</span> -day-time, and towards the moon and stars at -night, as described in the preceding chapter. -By means of this instrument you can direct your -course towards cities and islands and any other -place wherever you may wish to go by land or -sea, provided the latitude and longitude of the -places are known to you. How iron remains -suspended in air by virtue of the lodestone, I -will explain in my book on the action of mirrors. -Such, then, is the description of the instrument -illustrated below. (See Figs. <a href="#fig2">2</a> and <a href="#fig3">3</a>.)</p> -<div class="img" id="ill2"> -<img id="fig2" src="images/i_p30.jpg" alt="FIG. 2.—DOUBLE-PIVOTED NEEDLE" width="126" height="188" /> -<p class="pcap">FIG. 2.—DOUBLE-PIVOTED NEEDLE</p> -</div> -<div class="img" id="ill3"> -<img id="fig3" src="images/i_p30a.jpg" alt="FIG. 3.—PIVOTED COMPASS" width="500" height="134" /> -<p class="pcap">FIG. 3.—PIVOTED COMPASS</p> -</div> -<div class="pb" id="Page_31">31</div> -<h3>CHAPTER III -<br />THE ART OF MAKING A WHEEL OF PERPETUAL MOTION</h3> -<p>In this chapter I will make known to you the -construction of a wheel which in a remarkable -manner moves continuously. I have seen -many persons vainly busy themselves and even -becoming exhausted with much labor in their -endeavors to invent such a wheel. But these invariably -failed to notice that by means of the virtue -or power of the lodestone all difficulty can be -overcome. For the construction of such a wheel, -take a silver capsule like that of a concave mirror, -and worked on the outside with fine carving -and perforations, not only for the sake of -beauty, but also for the purpose of diminishing -its weight. You should manage also that the -eye of the unskilled may not perceive what is -cunningly placed inside. Within let there be -<span class="pb" id="Page_32">32</span> -iron nails or teeth of equal weight fastened to -the periphery of the wheel in a slanting direction, -close to one another so that their distance -apart may not be more than the thickness of a -bean or a pea; the wheel itself must be of uniform -weight throughout. Fasten the middle of -the axis about which the wheel revolves so that -the said axis may always remain immovable. Add -thereto a silver bar, and at its extremity affix a -lodestone placed between two capsules and prepared -in the following way: When it has been -rounded and its poles marked as said before, let -it be shaped like an egg; leaving the poles untouched, -file down the intervening parts so that -thus flattened and occupying less space, it may -not touch the sides of the capsules when the -wheel revolves. Thus prepared, let it be attached -to the silver rod just as a precious stone is placed -in a ring; let the north pole be then turned towards -the teeth or cogs of the wheel somewhat -slantingly so that the virtue of the stone may not -flow diametrically into the iron teeth, but at a -certain angle; consequently when one of the -<span class="pb" id="Page_33">33</span> -teeth comes near the north pole and owing to -the impetus of the wheel passes it, it then approaches -the south pole from which it is rather -driven away than attracted, as is evident from the -law given in a preceding chapter. Therefore such -a tooth would be constantly attracted and constantly -repelled.</p> -<div class="img" id="ill4"> -<img id="fig4" src="images/i_p33.jpg" alt="FIG. 4.—PERPETUAL MOTION WHEEL" width="500" height="499" /> -<p class="pcap">FIG. 4.—PERPETUAL MOTION WHEEL</p> -</div> -<p>In order that the wheel may -do its work more speedily, place within the box a -small rounded weight made of brass or silver of -such a size that it may be caught between each -pair of teeth; consequently as the movement of -<span class="pb" id="Page_34">34</span> -the wheel is continuous in one direction, so the -fall of the weight will be continuous in the other. -Being caught between the teeth of a wheel which -is continuously revolving, it seeks the centre of the -earth in virtue of its own weight, thereby aiding -the motion of the teeth and preventing them from -coming to rest in a direct line with the lodestone. -Let the places between the teeth be suitably -hollowed out so that they may easily catch -the body in its fall, as shown in the diagram -above. (<a href="#fig4">Fig. 4</a>.)</p> -<p>Farewell: finished in camp at the siege of -Lucera on the eighth day of August, Anno Domini -MCCLXIX.</p> -<div class="pb" id="Page_35">35</div> -<h2 id="c5">NOTES</h2> -<div class="pb" id="Page_37">37</div> -<h3>EARLY REFERENCES TO THE MARINER’S COMPASS</h3> -<p>The following are the passages referred to in the introductory -notice:</p> -<p>Abbot Neckam (1157-1217), in his <i>De Naturis Rerum</i>, -writes:</p> -<p>“The sailors, moreover, as they sail over the sea, when in -cloudy weather they can no longer profit by the light of the sun, -or when the world is wrapped up in the darkness of the shades -of night and they are ignorant to what point their ship’s course -is directed, these mariners touch the lodestone with a needle, -which (the needle) is whirled round in a circle until when its -motion ceases, its point looks direct to the north. (<i>Cuspis -ipsius septentrionalem plagam respiciat.</i>)”</p> -<p>In his <i>De Utensilibus</i>, we read:</p> -<p>“Among other stores of a ship, there must be a needle -mounted on a dart (<i>habeat etiam acum jaculo superpositam</i>) -which will oscillate and turn until the point looks to the north, -and the sailors will thus know how to direct their course when -<span class="pb" id="Page_38">38</span> -the pole star is concealed through the troubled state of the atmosphere.”<a class="fn" id="fr_5" href="#fn_5">[5]</a></p> -<p>Alexander Neckam was born at St. Albans in 1157, joined -the Augustinian Order and taught in the University of Paris -from 1180 to 1187, after which he returned to England to take -charge of a College of his Order at Dunstable. He was elected -Abbot of Cirencester in 1213 and died at Kemsey, near Worcester, -in 1217.</p> -<p class="tb">The satirical poem of Guyot de Provins, written about -1208, contains the following passage:</p> -<div class="verse"> -<p class="t0">The mariners employ an art which cannot deceive,</p> -<p class="t0">By the property of the lodestone,</p> -<p class="t0">An ugly stone and brown,</p> -<p class="t0">To which iron joints itself willingly</p> -<p class="t0">They have; they attend to where it points</p> -<p class="t0">After they have applied a needle to it;</p> -<p class="t0">And they lay the latter on a straw</p> -<p class="t0">And put it simply in the water</p> -<p class="t0">Where the straw makes it float.</p> -<p class="t0">Then the point turns direct</p> -<p class="t0">To the star with such certainty</p> -<p class="t0">That no man will ever doubt it,</p> -<p class="t0">Nor will it ever go wrong.</p> -<p class="t0">When the sea is dark and hazy,</p> -<p class="t0">That one sees neither star nor moon,</p> -<p class="t0">Then they put a light by the needle</p> -<p class="t0">And have no fear of losing their way.</p> -<p class="t0">The point turns towards the star;</p> -<div class="pb" id="Page_39">39</div> -<p class="t0">And the mariners are taught</p> -<p class="t0">To follow the right way.</p> -<p class="t0">It is an art which cannot fail.</p> -</div> -<p>Provins, from which Guyot took his surname, was a small -town in the vicinity of Paris.</p> -<p class="tb">Cardinal Jacques de Vitry, in his <i>Historia Orientalis</i>, Cap. -89, writes:</p> -<p>“An iron needle, after having been in contact with the -lodestone, turns towards the north star, so that it is very necessary -for those who navigate the seas.”</p> -<p>Jacques de Vitry was born at Argenteuil, near Paris, joined -the fourth crusade, became Bishop of Ptolemais, and died in -Rome in 1244. He wrote his “Description of Palestine,” -which forms the first book of his <i>Historia Orientalis</i>, in the -East, between 1215 and 1220.</p> -<p class="tb">Albertus Magnus (1193-1280) in his <i>De Mineralibus</i>, Lib. -II., Tract 3, Cap. 6, writes:</p> -<p>“It is the end of the lodestone which makes the iron that -touched it turn to the north (<i>ad zoron</i>) and which is of use to -mariners; but the other end of the needle turns toward the -south (<i>ad aphron</i>).”</p> -<p>This illustrious Bavarian schoolman joined the Dominican -Order in his youth, lectured to great audiences in Cologne, became -bishop of Ratisbonne in 1260, and died in 1280. Thomas -Aquinas the greatest of schoolmen, was among his pupils.</p> -<div class="pb" id="Page_40">40</div> -<p class="tb">In the Spanish code of laws, begun in 1256, during the -reign of Alfonso el Sabio, and known as <i>Las Siete Partidas</i>, we -read:</p> -<p>“Just as mariners are guided during the night by the -needle, which replaces for them the shores and pole star alike, -by showing them the course to pursue both in fair weather and -foul, so those who are called upon to advise the King must always -be guided by a spirit of justice.”</p> -<p class="tb">Brunetto Latini, in his <i>Trésor des Sciences</i>, 1260, writes:</p> -<p>“The sailors navigate the seas guided by the two stars -called the tramontanes, and each of the two parts of the lodestone -directs the end of the needle to the star to which that part -itself turns.”</p> -<p>Brunetto Latini (1230-1294) was a man of great eminence -in the thirteenth century; Dante was among his pupils at Florence. -For political reasons, he removed to Paris, where he -wrote his <i>Trésor</i> and also his <i>Tesoretto</i>. He visited Roger -Bacon at Oxford about 1260.</p> -<p class="tb">In his treatise <i>De Contemplatione</i>, begun in 1272, Raymond -Lully writes:</p> -<p>“As the needle, after having touched the lodestone, turns -to the north, so the mariner’s needle (<i>acus nautica</i>) directs them -over the sea.”</p> -<p>Lully was born at Palma in the Island of Majorca in -1236; he joined the Third Order of St. Francis, dying in 1315.</p> -<div class="pb" id="Page_41">41</div> -<p class="tb">Ristoro d’Arezzo, in his <i>Libro della Composizione del -Mundo</i>, written in 1282, has the following:</p> -<p>“Besides this, there is the needle which guides the mariner, -and which is itself directed by the star called the tramontane.”<a class="fn" id="fr_6" href="#fn_6">[6]</a></p> -<p class="tb">The following metrical translation of a poem by Guido -Guinicelli, an Italian priest, 1276, is from the pen of Dr. Park -Benjamin, of New York:</p> -<div class="verse"> -<p class="t0">In what strange regions ’neath the polar star</p> -<p class="t0">May the great hills of massy lodestone rise,</p> -<p class="t0">Virtue imparting to the ambient air</p> -<p class="t0">To draw the stubborn iron; while afar</p> -<p class="t0">From that same stone, the hidden virtue flies</p> -<p class="t0">To turn the quivering needle to the Bear</p> -<p class="t0">In splendor blazing in the Northern skies.</p> -</div> -<p>The above extracts show that the directive property of the -magnetic needle was well known in England, France, Germany, -Spain and Italy in the thirteenth century. In the passage from -Neckam, the <i>acum jaculo superpositam</i> has been construed by -some to mean a form of pivoted needle, while in the letter of -Peregrinus, 1269, the double pivoted form is clearly described.</p> -<h2 id="c6">Footnotes</h2> -<div class="fnblock"><div class="fndef"><a class="fn" id="fn_1" href="#fr_1">[1]</a>With very few exceptions all the works referred to in this notice will -be found in the Wheeler Collection in the Library of the American Institute -of Electrical Engineers, New York. -</div><div class="fndef"><a class="fn" id="fn_2" href="#fr_2">[2]</a>It is probable that Flavio Gioja, an Italian pilot, some fifty years -later, added the compass-card and attached it to the magnet. -</div><div class="fndef"><a class="fn" id="fn_3" href="#fr_3">[3]</a>Annali di Matematica Pura ed Applicata, 1865. -</div><div class="fndef"><a class="fn" id="fn_4" href="#fr_4">[4]</a>A terrella, or earthkin. -</div><div class="fndef"><a class="fn" id="fn_5" href="#fr_5">[5]</a>The Chronicles and Memoirs of Great Britain and Ireland during -the Middle Ages, by Thomas Wright (1863). -</div><div class="fndef"><a class="fn" id="fn_6" href="#fr_6">[6]</a>The -pole-star was thus named in the south of France and the north -of Italy because seen beyond the mountains (the Alps). -</div> -</div> -<h2 id="c7">Transcriber’s Notes</h2> -<ul><li>Retained publication and copyright information from the original; this eBook is public-domain in the U.S.</li> -<li>Silently corrected a few palpable typographical errors.</li> -<li>In the text versions, enclosed italicized text in _underscore_.</li></ul> - - - - - - - -<pre> - - - - - -End of the Project Gutenberg EBook of The Letter of Petrus Peregrinus on the -Magnet, A.D. 1269, by Petrus Peregrinus - -*** END OF THIS PROJECT GUTENBERG EBOOK LETTER OF PETRUS PEREGRINUS ON MAGNET *** - -***** This file should be named 50524-h.htm or 50524-h.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/0/5/2/50524/ - -Produced by deaurider, Stephen Hutcheson, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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