This myth of the magnetic mountains, probably originating with Nicander, appears, possibly from an independent source, in the East, in China, and in the tales of the Arabian Nights. Ptolemy gives the following account in his _Geographia_ (lib. vii., cap. 2): [Greek: Pherontai de kai allai sunecheis deka nêsoi kaloumenai Maniolai en ais phasi ta sidêrous echonta hêlous ploia katechesthai, mêpote tês Hêrikleias lithou peri autas genomenês, kai dia touto epiourois naupêgeisthai.] Some editions omit the name of the Manioles from the passage. No two authorities agree as to the place of these alleged magnetic mountains. Some place them in the Red Sea. Fracastorio, _De Sympathia et Antipathia_, cap. 7 (_Opera omnia_, Giunta edition, 1574, p. 63), gives the following reason for the variation of the compass: "Nos igitur diligentius rem considerãtes dicimus causam, [~q] perpendiculum illud ad polum vertatur, esse montes ferri, & magnetis, qui sub polo sunt, vt negociatores affirmant, quorum species per incredibilem distantiam vsque ad maria nostra propagata ad perpendiculum vsq;, vbi est magnes, consuetam attractionem facit: propter distantiam autem quum debilis sit, non moueret quidem magnetem, nisi esset in perpendiculo: quare & si non trahit vsq; ac. principium, vnde effluxit, at mouet tam[~e], & propinquiorem facit, quo potest. Quod si naues sorte vllæ propinquiores sint illis montibus, ferrum omne ear[~u] cuellitur, propter quod nauigijs incolæ vtuntur clauis ligneis astrictis." In the last chapter of his _De Sympathia_, Fracastorio returns to the subject {13} in consequence of some doubts expressed by Giambattista Rhamnusio, seeing that the loadstones in the Island of Elba do not sensibly deflect the magnet. Fracastorio replies thus (p. 76, _op. citat._):