Chap. IV, of the science of the discovery of the parts of the loadstone; Chap. V, of the source of the discovery of poles in the loadstone--which of them is the north and which the south; Chap. VI, in what manner a magnet attracts a magnet; Chap. VII, how iron touched with the magnet turns towards the poles of the globe; Chap. VIII, in what manner a magnet attracts iron; Chap. IX, why the northern part attracts the southern part, and the converse; Chap. X, of the inquiry whence the magnet derives the natural power it possesses. [Illustration: Petrus Peregrinus. “Epistola ... de Magnete.” The earliest known treatise of experimental science, now in the Bibliothèque Nationale, Paris.] Of Part II: Chap. I, on the construction of an instrument (floating compass) by which the azimuth of the sun and moon, and of any star above the horizon, can be ascertained; Chap. II, on the construction of a better instrument (pivoted compass) for like purpose; Chap. III, on the construction of a wheel for perpetual motion. An analyzation of each chapter in turn will show how satisfactorily Peregrinus has developed, in connected series, all of the early experiments upon which are based his theories of the loadstone. PART I Chap. I states that the intention or object of the work is to make known the hitherto hidden nature, occult properties, of the loadstone, the art of treating the latter, the making of scientific instruments, and matters of interest to students of nature, astrologers and sailors. Chap. II. The investigator in this line should know the natures of things and understand the motions of the heavenly bodies, but, above all, he should be assiduous in handiwork for experimental research. Chap. III indicates four different requisite qualities of the loadstone, and tells where they are to be found and how to select and test them--the best of them being free from flaws, of great density and of a bluish or celestial colour. Chap. IV shows how to find in the loadstone the two poles, one north and the other south, using preferably a globular magnet,[17] placing thereon a needle or an oblong piece of iron, and, either drawing lines in the direction taken by the needle, so that they “may meet at two points, just as all the meridian circles of the world meet at the two opposite poles of the world,” or, by merely marking the magnet so that “the opposite points will be correctly placed just as are the poles in a sphere.”