t magnetum."

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 nesoi kaloumenai Maniolai en
ais phasi ta siderous echonta helous ploia katechesthai, mepote tes
Herikleias lithou peri autas genomenes, kai dia touto epiourois
naupegeisthai.] 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 considerates 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 vllae propinquiores sint illis montibus, ferrum
omne ear[~u] cuellitur, propter quod nauigijs incolae 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._):

"Primum igitur vtrum sub Polo sint. Magnetis m[~o]tes, nec ne, sub ambiguo
relinquamus, scimus enim esse, qui scribat planas magis esse eas regiones,
de quo Paulus Iouius E[~p]us Nucerinus Lucul[~e]tus historiar[~u] nostri
t[~e]poris scriptor, circa ea Sarmatiae partem, quae Moscouia n[~u]c
dicitur, diligent[~e] inquisitionem ab incolis fecit, qui ne eos etia
inueniri montes retulere, qui Rhyphei ab antiquis dicti sunt: meminimus
tam[~e] nos quasdam chartas vidisse earum, quas mundi mappas appellat, in
quibus sub polo montes notati erant (qui Magnetis montes inscripti
fuerant). Siue igitur sint, siue non sint ij montes, nihil ad nos in
praesen