"Magnes lapis optimus est, qui ferrum facile trahit, colore ad coeruleum uergente, densus, nec admodum gravis. Datur cum aqua mulsa, trium obolorum pondere, ut crassos humores eliciat. Sunt qui magnetem cremat[=u] pro hæmatite vendant...." In the _Scholia_ of Joannes Lonicerus upon Dioscorides _In Dioscoridæ {31} Anazarbei de re medica libros a Virgilio Marcello versos, Scholia nova, Ioanne Lonicero autore_ (Marburgi, 1543, p. 77), occurs the following: "_De recremento ferri._ Cap. XLIX. "[Greek: Skôria sidêrou]. scoria vel recrementum ferri. Quæ per ignem à ferro et cupro sordes separantur ac reijciuntur, et ab aliis metallis [Greek: skôria] uocantur. Omnis scoria, maxime uero ferri exiccat. Acerrimo aceto macerauit Galenus ferri scoriam, ac deinde excocto, pharmacum efficax confecit ad purulentas quæ multo tempore uexatæ erant, aures, admirando spectantium effectu. Ardenti scoria uel recrementum [Greek: helkusma], inquit Galenus." See also the _Enarrationes eruditissimæ_ of Amatus Lusitanus (Venet., 1597), pp. 482 and 507, upon iron and the loadstone. [98] PAGE 36, LINE 27. Page 36, line 29. _eijcitur_ for _ejicitur_. [99] PAGE 37, LINE 18. Page 37, line 22. _ut Cardanus philosophatur._--Cardan's nonsense about the magnet feeding on iron is to be found in _De Subtilitate_, lib. vii. (Basil., 1611, p. 381). [100] PAGE 38, LINE 4. Page 38, line 7. _ferramenta ... in usum navigantium._--Compare Marke Ridley's _A Short Treatise of Magneticall Bodies and Motions_ (Lond., 1613), p. _a2_ in the _Preface Magneticall_, where he speaks of the "iron-workes" used in building ships. The phraseology of Marke Ridley throws much light on the Latin terms used by Gilbert. [101] PAGE 38, LINE 36. Page 38, line 42. _vruntur;_ changed in ink to _vrantur_ in the folio of 1600; but _uruntur_ appears in the editions of 1628 and 1633. [102] PAGE 39, LINE 12. Page 39, line 12. _virumque;_ altered in ink to _virunque_ in all copies of the folio edition of 1600. [103] PAGE 40, LINE 32. Page 40, line 33. _ad tantos labores exantlandos._--Pumping, as it was in mining before the invention of the steam engine, may best be realized by examining the woodcuts in the _De re metallica_ of Georgius Agricola (Basil., Froben, 1556). [104] PAGE 40, LINE 34. Page 40, line 36. _quingentas orgyas._--Gilbert probably had in his mind the works of the Rorerbühel, in the district of Kitzbühl, which in the sixteenth century had reached the depth of 3,107 feet. See Humboldt's _Cosmos_ (Lond., 1860, vol. i., p. 149). [105] PAGE 43, LINE 34. Page 43, line 33. _glis._--This word, here translated _grit_, does not appear to be classical Latin; it may mean _ooze or slime_. [106] PAGE 45, LINE 25. Page 45, line 26. _Motus igitur ... quinque._ The five kinds of magnetic motions correspond in fact to the remaining sections of the book; as follows: _Coitio_, Book II.; _Directio_, Book III.; _Variatio_, Book IV.; _Declinatio_, Book V.; and _Revolutio_, Book VI.