726 COSKOS. 



1600, under the title of "Physiology of magnets and of th 

 earth as a great magnet (de magno magnete tellure.)" " The 

 property," says Gilbert, " of attracting light substances, 

 when rubbed, be their nature what it may, is not peculiar 

 to amber, which is a condensed earthy juice cast up by the 

 waves of the sea, and in which flying insects, ants, and 

 worms lie entombed as in eternal sepulchres (aBternis sepul- 

 chris). The force of attraction belongs to a whole class of 

 very different substances, as glass, sulphur, sealing-wax, and 

 all resinous substances, rock crystal, and all precious stones, 

 alum, and rock salt." Gilbert measured the strength of the 

 excited electricity by means of a small needle, not made of 

 iron, which moved freely on a pivot (versortum electricum), 

 and perfectly similar to the apparatus used by Hauy and 

 Brewster in testing the electricity excited in minerals by heat 

 and friction. " Friction," says Gilbert further, " is produc- 

 tive of a stronger effect in dry than in humid air ; and rub- 

 bing with silk cloths is most advantageous. The globe is 

 held together as by an electric force (?) Globus telluris per 



effluvia electrica, attractiones electricae. We do not find either the 

 abstract expression electricitas, or the barbarous word magnetismus 

 introduced in the eighteenth century. On the derivation of ijXeicTpov, 

 "the attractor and the attracting stone," from *Ai and sXicsiv already 

 indicated in the Timaeus of Plato, p. 80 c, and the probable transition 

 through a harder tXtKTpov, see Buttmann, Mythologus, bd. ii. (1829), 

 g. 357. Among the theoretical propositions put forward by Gilbert 

 (which are not always expressed with equal clearness), I give the follow- 

 ing : " Cum duo sint corporum genera, quae manifestis sensibus nostris 

 motionibus corpora allicere videntur, Electrica et Magnetica ; Electrica 

 naturalibus ab humore effluviis ; Magnetica formalibus efficicntiis seu 

 potius primariis vigoribus, incitationes faciunt. Facile est homini- 

 bus ingeriio acutis, absque experimentis et usu rerum labi, et errare. 

 Substantive proprietates aut familiaritates, sunt generales nimis, nee 

 tamen verae designatae causae, atque, ut ita dicam, verba quaedam 

 Bonant, re ipsa nihil in specie ostendunt. Neque ista succini credita 

 attractio, a singular! aliquot proprietate substantiae, aut familiaritate 

 assurgit; cum in pluribus aliis corporibus eundem effectum, majori indus- 

 tria invenimus, et omnia etiam corpora cujusmodicunque proprietatis, 

 ab omnibus illiis alliciuntur." (De Magnete, pp. 50, 51, 60, and 65.) 

 Gilbert's principal labours appear to fall between the years from 1590 to 

 1600. Whe well justly assigns him an important place among those whom 

 he terms "practical reformers of the physical sciences." Gilbert was 

 Burgeon to Queen Elizabeth and James I., and died in 1603. After hia 

 death there appeared a second work, entitled " De Mundo nwtro sub- 

 lunari Philosophia Nova" 



