cum rediens, ui ferrum fecum rapit & trahit. At
Electrum uim quandam flammae similem & spiritalem continet, quam quidem
{44} tritu summae partis, quo aperiuntur meatus, foras eijcit. Nam
leuissima corpuscula & aridissima quae prope sunt, sua tenuitate atque
imbecillitate ad seipsum ducit & rapit, cum non sit adeo ualens, nec tantum
habeat ponderis & momenti ad expellendam aeris copiam, ut maiora corpora
more Magnetis superare possit & uincere."

[138] PAGE 54, LINE 16. Page 54, line 18. _Gemma Vincentij rupis._--See the
note to p. 48 _supra_, where the name _Vincentina_ occurs.

[139] PAGE 54, LINE 30. Page 54, line 35. _orobi._--The editions of 1628
and 1633 read _oribi_.

[140] PAGE 55, LINE 34. Page 55, line 42. _in euacuati._--The editions of
1628 and 1633 read _inevacuati_.

[141] PAGE 58, LINE 21. Page 58, line 25. _assurgentem vndam ... declinat
ab F._--These words are wanting in the Stettin editions.

[142] PAGE 59, LINE 9. Page 59, line 9. _fluore._--This word is conjectured
to be a misprint for _fluxu_ but it stands in all editions.

[143] PAGE 59, LINE 22. Page 59, line 25. _Ruunt ad electria._--This
appears to be a slip for _electrica_, which is the reading of the editions
of 1628 and 1633.

[144] PAGE 60, LINE 7. Page 60, line 9. _tan[=q] materiales radij._--The
suggestion here of material _rays_ as the _modus operandi_ of electric
forces seems to foreshadow the notion of electric lines of force.

[145] PAGE 60, LINE 10. Page 60, line 12. _Differentia inter magnetica &
electrica._--Though Gilbert was the first systematically to explore the
differences that exist between the magnetic attraction of iron and the
electric attraction of all light substances, the point had not passed
unheeded, for we find St. Augustine, in the _De Civitate Dei_, liber xxi.,
cap. 6, raising the question why the loadstone which attracts iron should
refuse to move straws. The many analogies between electric and magnetic
phenomena had led many experimenters to speculate on the possibility of
some connexion between electricity and magnetism. See, for example,
Tiberius Cavallo, _A Treatise on Magnetism_, London, 1787, p. 126. Also the
three volumes of J. H. van Swinden, _Receuil de Memoires sur l'Analogie de
Electricite et du Magnetisme_, La Haye, 1784. Aepinus wrote a treatise on
the subject, entitled _De Similitudine vis electricae et magneticae_
(Petropolis, 1758). This was, of course, long prior to the discovery, by
Oersted