250 THE INTELLECTUAL RISE IN ELECTRICITY. 



removal of foreign matters or a scale, of which he else- 

 where speaks, attached to the natural lodestone, which he 

 supposed impaired its force. He knew that the power 

 could not thus be cut off. 



This having been said in the sixteenth century and not 

 in the nineteenth, the necessity obtruded itself of reconcil- 

 ing his plainly experimental results with his previously- 

 announced theory. He sees that the link must be a physical 

 and not a metaphysical one. Instinctively the leech finds 

 his analogy in an instrument of torture still lingering in 

 the chirurgical armament. The hotter the amber, he 

 thinks, the more it draws just like the action of "the 

 cupping glass due to fire and hot things;" and there he 

 rests content, oblivious of the hopeless inconsistency of 

 this notion with that part of his theory which accounts 

 for the phenomenon by the attraction between dry and 

 moist bodies. The cupping-glass idea was his own the 

 rest of the analogy he borrowed from the ancients. 



That Sarpi knew of this remarkable differentiation of 

 magnet and amber, is hardly to be doubted ; and it may 

 be surmised that his master mind perceived the conse- 

 quences, which others pointed out. But there is nothing 

 in Porta's reflection of Sarpi's light to support this ; and 

 the loss of Sarpi's writings leaves the matter probably 

 forever in obscurity. Porta himself seems to have attached 

 no importance to the subject, although he shows abundant 

 familiarity with Cardan's work. Indeed, at times he fairly 

 revels in disputing the assertions of the Milanese physician, 

 in terms so much more vigorous than refined, that it is 

 not difficult to imagine that the Neapolitan philosopher 

 had imbibed his notions of Cardan from those life-long 

 rivals who had furnished the older scholar abundant basis 

 for his epigrammatic definition of envy as "mild hate." 



Cardan, for example, avers that iron is the magnet's 

 food ; so not only accounts for magnetic attraction, but in- 

 sists that a magnet is best preserved in iron filings : which 

 may be perfectly true if the filings are packed in a dense 



