[122] PAGE 48, LINE 18. Page 48, line 20. _Similes etiam attrahendi vires habere videntur vitrum ... sulphur, mastix, & cera dura sigillaris._ If, as shown above, the electric powers of diamond and ruby had already been observed, yet Gilbert was the first beyond question to extend the list of _electrics_ beyond the class of precious stones, and his discovery that _glass_, _sulphur_, and _sealing-wax_ acted, when rubbed, like amber, was of capital importance. Though he did not pursue the discovery into mechanical contrivances, he left the means of that extension to his followers. To Otto von Guericke we owe the application of sulphur to make the first electrical machine out of a revolving globe; to Sir Isaac Newton the suggestion of glass as affording a more mechanical construction. Electrical attraction by natural products other than amber after they have been rubbed must have been observed by the primitive races of mankind. Indeed Humboldt in his _Cosmos_ (Lond., 1860, vol. i., p. 182) records a striking instance: "I observed with astonishment, on the woody banks of the Orinoco, in the sports of the natives, that the excitement of electricity by friction was known to these savage races, who occupy the very lowest place in the scale of humanity. Children may be seen to rub the dry, flat and shining seeds or husks of a trailing plant (probably a _Negretia_) until they are able to attract threads of cotton and pieces of bamboo cane." [123] PAGE 48, LINE 23. Page 48, line 25. _arsenicum_.--This is _orpiment_. See the _Dictionary of metallick words_ at the end of Pettus's _Fleta Minor_. [124] PAGE 48, LINE 23. Page 48, line 26. _in convenienti coelo sicco_.--The observation that only in a dry climate do rock-salt, mica, and rock-alum act as electrics is also of capital importance. Compare page 56. [125] PAGE 48, LINE 27. Page 48, line 31. _Alliciunt hæc omnia non festucas modo & paleas._--Gilbert himself marks the importance of this discovery by the large asterisk in the margin. The logical consequence was his invention of the first _electroscope_, the _versorium non magneticum_, made of any metal, figured on p. 49. [126] PAGE 48, LINE 34. Page 48, line 36. _quod tantum siccas attrahat paleas, nec folia ocimi._--This silly tale that basil leaves were not attracted by amber arose in the _Quæstiones Convivales_ of Plutarch. It is repeated by Marbodeus and was quoted by Levinus Lemnius as true. Gilbert denounced it as nonsense. Cardan (_De Subtilitate_, Norimb., 1550, p. 132) had already contradicted the fable. "Trahit enim," he says, "omnia levia, paleas, festucas, ramenta {42} tenuia metallorum, & ocimi folia, perperam contradicente Theophrasto." Sir Thomas Browne specifically refuted it. "For if," he says, "the leaves thereof or dried stalks be stripped into small strawes, they arise unto Amber, Wax, and other Electricks, no otherwise then those of Wheat or Rye."