Several attempts at translation have been made, notably by Guillaume Libri (“Histoire des Sciences Mathématiques ...” Paris, 1838, Vol. II. p. 487) who admitted that, with the aid of several paleographers, he could not decipher many of the abbreviated faint characters existing in the Bibliothèque Nationale manuscript (No. 7378A in quarto, at folio 67), and by Tiberius Cavallo, who does scarcely better with the Leyden copy (Fol. Cod. No. 227) which was discovered by him, and but a portion of which he transcribes in the supplement to his “Treatise on Magnetism,” London, 1800, pp. 299–320. A translation was also made by Brother Arnold, of the La Salle Institute in Troy, N.Y., and published during 1904, but the most meritorious version now existing is the one entitled “Done into English by Silvanus P. Thompson from the printed Latin versions of Gasser 1558, Bertelli 1868, and Hellmann 1898, and amended by reference to the manuscript copy in his possession, formerly amongst the Phillipps’ manuscripts, dated 1391.” This translation, “printed in the year 1902, in the Caxton type, to the number of 250 copies,” reflects very great credit upon Prof. Thompson, who has given us such a faithful interpretation of the original work as would naturally be expected at his hands, and who has, besides, rubricated this right royal little volume and caused it to be issued in one of the most attractive typographical fashions of the Chiswick Press. The Hellmann 1898 Berlin version just alluded to, which appeared in “Neudrucke von Schriften und Karten ...” No. 10 (_Rara Magnetica_), contains a photographic reproduction of the Augsburg 1558 title-page, and, it may be added, the volume of Phillipps’ manuscripts, of which Prof. Thompson became the fortunate possessor, includes one of Chaucer’s treatises on the Astrolabe, besides the Peregrinus’ manuscript in question. During the year 1562 much of the original epistle was pilfered by Joannes Taisnier Hannonius, who badly condensed and deformed it and incorporated it as new matter, conjointly with some papers of his own, in a book entitled “Oposculum ... de Natura Magnetis et ejus effectibus ...” Coloniæ, 1562; and that much was translated “into Englishe” by Richarde Eden, London, about 1579, under title of “A very necessarie and profitable booke concerning navigation.” Much has been said at different times regarding the contents of the above-named epistle, the full title of the Paris MS. No. 7378 of which reads “_Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt militem de magnete_,” but no _résumé_ of it could better be given than by quoting here its first page, which has been translated as follows: This treatise on the magnet contains two parts, of which Part I is complete in ten chapters, and Part II in three. Of Part I: Chap. I states the object of the work; Chap. II, of what the investigator in this line of work should be; Chap. III, of a knowledge of the loadstone;