Augustine
repeats the diamond myth in his _De Civitate Dei_, lib. xxi. Baptista Porta
says (p. 211 of the English version of 1658): "It is a common Opinion
amongst Sea-men, That Onyons and Garlick are at odds with the Loadstone:
and Steers-men, and such as tend the Mariners Card are forbid to eat Onyons
or Garlick, lest they make the Index of the Poles drunk. But when I tried
all these things, found them to be false: for not onely breathing and
belching upon the Loadstone after eating of Garlick, did not stop its
vertues: but when it was all anoynted over with the juice of Garlick, it
did perform its office as well as if it had never been touched with it: and
I could observe almost not the least difference, lest I should make void
the endeavours of the Ancients. {5} And again, When I enquired of Marines,
whether it were so, that they were forbid to eat Onyons and Garlick for
that reason; they said, they were old Wives fables, and things ridiculous;
and that Sea-men would sooner lose their lives, then abstain from eating
Onyons and Garlick."

The fables respecting the antipathy of garlick and of the diamond to the
operation of the magnet, although already discredited by Ruellius and by
Porta, died hard. In spite of the exposure and denunciations of
Gilbert--compare p. 32--these tales were oft repeated during the succeeding
century. In the appendix to Sir Hugh Plat's _Jewel House of Art and
Nature_, in the edition of 1653, by D. B. Gent, it is stated there (p.
218): "The Loadstone which ... hath an admirable vertue not onely to draw
Iron to it self, but also to make any Iron upon which it is rubbed to draw
iron also, it is written notwithstanding, that being rubbed with the juyce
of Garlick, it loseth that vertue, and cannot then draw iron, as likewise
if a Diamond be layed close unto it."

Pliny wrote of the alleged antipathy between diamond and goat's blood. The
passage as quoted from the English version of Pliny's _Natural Historie of
the World_, translated by Philemon Holland (London, 1601, p. 610, chap,
iv.), runs: "But I would gladly know whose invention this might be to soake
the Diamond in Goats bloud, whose head devised it first, or rather by what
chance was it found out and knowne? What conjecture should lead a man to
make an experiment of such a singular and admirable secret, especially in a
goat, the filthiest beast ... in the whole world? Certes I must ascribe
both this invention and all such like to the migh