[156] PAGE 64, LINE 16. Page 64, line 24. _Cardinalis etiam Cusanus._--Cardinal de Cusa (Nicolas Khrypffs) wrote a set of dialogues on Statics, _Nicolai Cusani de staticis experimentis dialogus_ (1550), of which an English version appeared in London in 1650 with the title, _The Idiot in four books; the first and second of wisdom, the third of the minde, the fourth of statick experiments. By the famous and learned C. Cusanus._ In the fourth book _of statick Experiments, Or experiments of the Ballance_, occurs (p. 186) the following: "_Orat._ Tell me, if thou hast any device whereby the vertues of stones may be weighed. "_Id._ I thinke the vertue of the Load-stone might be weighed, if putting some Iron in one scale, and a Load-stone in the other, untill the ballance were even, then taking away the Load-stone, and some other thing of the same weight being put into the scale, the Load-stone were holden over the Iron, so that that scale wou'd begin to rise; by reason of the Load-stones attraction of the Iron, then take out some of the weight of the other scale, untill the scale wherein the iron is, doe sinke againe to the æquilibrium, or equality still holding the Load-stone unmovable as it was; I beleeve that by weight of what was taken out of the contrary scale, one might come proportionably to the weight of the vertue or power of the Load-stone. And in like manner, the vertue of a Diamond, might be found hereby, because {46} they say it hinders the Load-stone from drawing of Iron; and so other vertues of other stones, consideration, being alwayes had of the greatnesse of the bodyes, because in a greater body, there is a greater power and vertue." In the 1588 edition of Baptista Porta's _Magiæ Naturalis Libri xx._, in lib. vii., cap. xviii., occurs the description of the use of the balance to which Gilbert refers. [157] PAGE 67, LINE 21. Page 67, line 22. _aëris rigore._--All editions read thus, but the sense seems to require _frigore_. [158] PAGE 67, LINE 27. Page 67, line 31. _Fracastorius._--See his _De Sympathia_, lib. i., cap. 5 (Giunta edition, 1574, p. 60). [159] PAGE 68, LINE 5. Page 68, line 6. _Thaletis Milesij._--See the note to p. 11, line 26.