"Sagda is a stone, which the Chaldeans find sticking to ships, and they say it is greene as Porrets or Leekes."
[192] Page 111, line 8. Page 111, line 8. Euace.—Evax, king of the Arabs, is said to have written to Nero a treatise on the names, colours, and properties of stones. See the [note] on Marbodæus, p. [7], line 20.
[193] Page 113, line 14. Page 113, line 19. repulsus sit. The words read thus in all editions, but the sense requires repulsa sint.
[194] Page 113, line 23. Page 113, line 29. Electrica omnia alliciunt cuncta, nihil omninò fugant vnquam, aut propellunt. This denial of electrical repulsion probably arose from the smallness of the pieces of electric material with which Gilbert worked. He could hardly have failed to notice it had he used large pieces of amber or of sealing-wax. Electrical repulsion was first observed by Nicolas Cabeus, Philosophia Magnetica, Ferrara, 1629; but first systematically announced by Otto von Guericke in his treatise Experimenta Nova (ut vocantur) Magdeburgica, de Vacuo Spatio (Amstel., 1672).
[195] Page 113, line 29. Page 113, line 37. cùm de calore quid sit disputabimus.—The discussion of the nature of heat is to be found in Gilbert's De Mundo nostro Sublunari (Amstel., 1651), lib. i., cap. xxvi., pp. 77-88.
[196] Page 115, line 23. Page 115, line 23. trium vel quatuor digitorum.—Here as in all other places in Gilbert, digitus means a finger's breadth, so that three or four digits means a length of two or three inches, or from six to eight centimetres.
[197] Page 117, line 26. Page 117, line 25. ille Thebit Bencoræ trepidationis motus.
"Trepidation in the ancient Astronomy denotes a motion which in the Ptolemaic system was attributed to the firmament, in order to account for
several changes and motions observed in the axis of the world, and for which they could not account on any other principle." (Barlow's Mathematical Dictionary.)
[198] Page 118, line 10. Page 118, line 8. cuspis is aut lilium.—Gilbert uses cuspis or lilium always of the North-pointing end of the needle. Sir Thomas Browne speaks of "the lilly or northern point"; but he differs from Gilbert in saying "the cuspis or Southern point" (Pseudodoxia Epidemica, 1650, p. 46). Only in one place (p. [101], line 5) does Gilbert speak of cuspis meridionalis. Everywhere else the south-pointing end is called the crux.