CHAPTER XVIII 

 ELECTRICITY. 



DERIVATION OF ELECTRICITY SEALING-WAX EXPERIMENT THE 



ELECTROPHORUS LEYDEN JAR POSITIVE AND NEGATIVE THE 



ELECTROSCOPE ELECTRIC MACHINES. 



WE have now briefly and of course imperfectly reviewed the phenomena of 

 Vibration, as exemplified in what we term Heat, Light, and Sound. We 

 now come to a most mysterious servant of mankind, as mysterious as any 

 Djinn of romance ; viz., ELECTRICITY. 



The term Electricity is derived from the Greek word electron, meaning 

 " amber " ; because from amber the properties of what we call " Electricity " 

 were first discovered. Six hundred years before the Christian Era, Thales 

 wrote concerning the attraction which amber, when rubbed, possessed for 

 light and dry bodies. But it is to an Englishman named Gilbert that we 

 owe the word " Electricity," which he derived from the Greek, and in his 

 works (about 1 600 A.D.) he discusses the force of the so-called " fluid." 

 Otto von Guerike, of " air-pump " celebrity, and many other philosophers 

 after him, continued the investigation of the subject. At the beginning of 

 the last century great attention was paid to the Electric Machine. The 

 Leyden Jar was, as its name denotes, discovered by Muschenbrock, of Leyden, 

 (though the honour was disputed). Franklin made the first lightning conductor 

 in 1760. Volta and Galvani, to whose invention we owe "Voltaic Electri- 

 city " and " Galvanism," and Faraday in more modern times gave a great 

 impetus to electrical science. The great part that electricity has been 

 playing in the domestic history of the world since Faraday's lamented death, 

 is probably known to the youngest of our readers. What the future of this 

 agent may be we can only guess, but even now we may regard electricity 

 as only in its infancy. 



There are few scientific studies more attractive to the general reader 

 than electricity, and few admit of more popular demonstration. The success 

 of the late electrical exhibition in Paris, and its successor in London at the 

 present time, are proofs of the interest taken in this great and mysterious 

 agent whose origin we are in ignorance of, and of whose nature and powers 

 we are daily discovering more and more, and finding there is still an 

 immense field for its application. 



Some fundamental facts regarding electricity may very easily be 

 studied with the assistance of every-day objects at hand. Amber was the 



