Chap. I. He takes a round, or an ovoid magnet, and, after noting its poles, files it between the two poles on both sides so that it may be like a compressed sphere and thus occupy less space. He then encloses this magnet between two light wooden capsules, or boxes (_cassulas_) after the manner of a mirror ... so fastened (with glue) that they cannot be opened and water cannot enter. Then, says he, “place the capsules thus adjusted in a large vessel full of water in which the two quarters of the globe, viz. the South and the North, are found and marked, and let them be indicated by a thread extending from the Northern to the Southern part of the vessel; allow the capsules, or boxes, to float and let there be above them a slender piece of wood in the form (position) of a diameter. Then move this piece of wood above the boxes until it is equidistant from the meridianal line previously found and indicated by the thread, or is the same (line) itself. This being done, according to the piece of wood so situated, draw a line on the capsules, or boxes, and it will be the perpetual meridianal line in all countries. That line, therefore, when cut at right angles by another will be divided in the centre and will be the line of the East and West. You will thus have four quadrants actually marked on the capsules, or boxes, representing the four quarters of the globe, of which each will be divided into ninety, so that there may be in the universe CCCLX parts (degrees) in the entire circumference of the capsules, or boxes. Inscribe divisions on it as they were formerly inscribed on the back of the astrolabe. There should be, besides, a slender and light ruler above the capsules so inscribed after the manner of the ruler on the back of the astrolabe. Instead, however, of the sights (_pinnularum_), should be erected at right angles two pins over the ends of the ruler.” This floating compass and the pivoted compass described in the following chapter are to be found illustrated, pp. 67–77, figs. 10 and 12, at end of Part II of Bertelli Barnabita’s Memoirs above referred to.