ELECTRICAL CONFERENCE AT PHILADELPHIA 625 



forth from the amber, which was so feeble as only to attract dust, now 

 flashed forth with light and sound and heat, and could cause the strength 

 of the giant to vanish. To the world at large there was now something 

 worth looking into. But do we think that the spark from the Leyden 

 jar is more wonderful than the gentle attraction of the amber? By no 

 means, for, to the scientist, they are both equally remarkable, and be- 

 yond our powers of explanation. It is only to the vulgar and unedu- 

 cated taste that the tinsel and gewgaws of an electric spark appeal more 

 strongly than the subtle spirit of the amber. Nevertheless, despicable 

 as the means, the spark of the Leyden jar acted as a trumpet call to 

 Europe and even America to come to the study of the wonderful science 

 of electricity. At no other time has there been such excitement over 

 any electrical discovery, and electrical experiments became general. 



It was only after the discovery of the Leyden jar that the idea of an 

 electric current occurred to mankind, and this current was even trans- 

 mitted to a distance by a wire and a shock given to a person across the 

 Thames, the water forming the return circuit. And the English ex- 

 perimenters even went so far as to form a circuit with the two observ- 

 ers two miles apart, using the earth as the return circuit. Thus the 

 fundamental fact which forms the basis of the telegraph was early ob- 

 served. 



But isolated facts are of little value unless connected together by 

 something which we call a theory, and in this line we owe much to 

 Franklin, whose letters upon this subject appeared between 1747 and 

 1754. To him we owe the theory of positive and negative electricity, 

 and the fact that they are always generated in equal amounts, a law 

 whose importance can scarcely be estimated. He investigated the Ley- 

 den jar, and showed that the coatings had equal positive and negative 

 charges, and explained the fact that the jar cannot be charged when 

 the outside coating is insulated. He invented the charge and discharge 

 by cascade and showed that it was the glass of the jar and not the 

 coatings which contained the charge. He discovered the property of 

 points in discharging an electrified body, and the identity of lightning 

 with electricity. He also made the first experiments upon atmospheric 

 electricity. 



To Canton is due the honor of giving the first experiments on induc- 

 tion, but Franklin is the first who gave the general law of this species 

 of action. Truly our country and this city should honor the memory 

 of this man. 



But it is not my purpose to repeat to you in detail the familiar history 

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