Them and the Loadstone, to recoil:
Brass in the middle made this broil.”
In Chap. XXXII he tells us that an Italian “whose name was Amalphus ... knew not the Mariner’s Card, but stuck the needle in a reed, or a piece of wood, cross over: and he put the needles into a vessel full of water that they might flote freely: then carrying about the loadstone, the needles would follow it: which being taken away, as by a certain natural motion, the points of the needles would turn to the north pole: and, having found that, stand still.... Now the Mariner’s Compass is made, and a needle touched with the Loadstone, is so fitted to it, that, by discovering the pole by it, all other parts of the heavens are known. There is made a rundle with a Latin-navel upon a point of the same metal, that it may run roundly freely. Whereupon, by the touching onely of one end, the needle not alone partakes of the vertues of it, but of the other end also, whether it will or not....”
Chap. XLVIII is headed “Whether Garlick can hinder the vertues of the loadstone.” By Porta we are informed that “Plutarch saith Garlick is at great enmity with the loadstone; and such antipathy and hatred there is between these invisible creatures, that if a loadstone be smeered with Garlick, it will drive away iron from it,” which is confirmed by Ptolemy, who states “that the loadstone will not draw iron, if it be anoynted with Garlick; as Amber will no more draw straws, and other light things to it, if they be first steeped in oyl.” He found that when the loadstone “was all anoynted over the juice of Garlick, it did perform its office as well as if it had never been touched with it.”
In Chap. LIII Porta denies “that the diamond doth hinder the loadstone’s vertue.” “Some pretend,” says he, “there is so much discord between the qualities of the loadstone and the diamond, and they are so hateful, one against the other, and secret enemies, that if the diamond be put to the loadstone, it presently faints and loses all its forces. (Pliny.) The loadstone so disagreeth with the diamond, that if iron be laid by it, it will not let the loadstone draw it; and if the loadstone do attract it, it will snatch it away again from it. (St. Augustine.) I will say that I have read of the loadstone: how that, if the diamond be by it, it will not draw iron; and, if it do when it comes neer the diamond, it will let it fall” (Marbodeus, of the Loadstone ... Marbodei Galli ... de lapidibus pretiosis Enchiridion ... Freiburg, 1530, 1531):
“All loadstones by their vertue iron draw;
But of the diamond it stands in awe:
Taking the iron from’t by Nature’s Law.”
“I tried this often, and found it false; and that there is no truth in it.”
With reference to the above, see Plat (at A.D. 1653), who also alludes to the fact of the softening of the diamond with Goat’s blood. This is alluded to by Porta in the next chapter.