EXPLANATION OF ELECTRICITY 



latter was the passage of a quantity of electricity 

 from a positive or negative to a more nearly neutral 

 stage. 



Then other discoveries intervened. The matter 

 hardly seemed so simple. First came Volta's in- 

 vention of the voltaic pile, as it came to be called 

 that from an alternate arrangement of different 

 metals, like copper and zinc, with bits of moist 

 paper in between, an electric current would arise. 

 From this came the modern battery, such as runs 

 our telephones and fans and electric- bells, and it 

 was with this that Davy produced such marvel- 

 lous effects, dissolving substances hitherto thought 

 to be elements, and showing the intimate relations 

 of electricity and chemical affinity. And after 

 this, Faraday, revealing how the armature of a 

 magnet, swung round mechanically in the mag- 

 netic field, would give rise to a new kind of cur- 

 rent, one that seemed to pulsate backward and 

 forward with extraordinary rapidity what used 

 to be called, to distinguish it from the voltaic cur- 

 rent, faradic electricity, as the first was called, 

 quite wrongfully, galvanic electricity, after Gal- 

 vani, the predecessor of Volta. Nowadays the lat- 

 ter is regarded simply as a continuous current, the 

 former the alternating current. 



Finally came the measurement of the speed at 

 which electricity travels. It was found to be the 



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