A REVIEW. 251 



mass to form an armature or keeper. Porta, however, as 

 has been recounted in the last chapter, retorted by bury- 

 ing a magnet with iron filings and occasionally digging it 

 up to see how much of the latter the magnet had de- 

 voured : a literal interpretation of Cardan's directions, 

 which, it is needless to add, was not attended with results. 

 On the other hand, Porta cordially agrees with Cardan, 

 that the virtue of the magnet cannot be destroyed by gar- 

 lic nor by the presence of the diamond. 



I have now reached the end of that epoch which im- 

 mediately precedes the earliest attempt to systemize elec- 

 trical and magnetic knowledge and thus to reduce it to a 

 science. In the rise of that knowledge through the cen- 

 turies we have seen the conception of the soul animating 

 the amber and the magnet give place to more material 

 hypotheses indeed to many of them in turn and ulti- 

 mately become degraded to a mere physical emanation or 

 to an appetite. We have found the phenomenon of mag- 

 netic attraction, familiar for centuries to the western 

 world, and that of magnetic polarity known for as long a 

 period to the nations of the east, and yet that there was 

 practically no interchange of this knowledge. In time, 

 however, we have seen this interchange take place, and 

 in tracing the separate items to their coalescence, we have 

 at the same time followed the evolution of the first great 

 electrical invention the mariner's compass. 



We have seen the enormous advance in human progress 

 directly owing to this instrument. We have perceived 

 that, although the amber phenomenon found no practical 

 application to the uses of man, still the inherent mystery, 

 the unexplained nature of it, was sufficient to impart to it 

 all the vitality inherent to a problem which constantly and 

 automatically forces itself upon generation after generation 

 for solution. After the compass had begun its great work, 

 after it had revealed the New World to the Old, the alii- 



