112 



ELECTRICITY. 



rases the spirits in all the spoons were inflamed apparently at the instant of the 

 discharge. 



Many of these properties were simultaneously discovered by Mr. Wilson, 

 who experimented in Dublin. He coated the external surface of the jar in the 

 first experiments by plunging it in water. He also made several experiments 

 with a view to affect by a shock one part of the human body without affecting 

 the otner parts. But the most remarkable discovery of this electrician was 

 the Inttrnl shock. He observed, that a person standing near the circuit through 

 which the shock is transmitted, would sustain a shock if he were only in con- 

 tact with any part of the circuit, or even placed very near it. 



Those who are conversant with the science, arid aware of the important 

 principle of induction, will see, with much interest, how nearly many of the 

 philosophers engaged in these researches touched, from time to time, on that 

 property, and yet missed the honor of its discovery. Without it, the explica- 

 tion of the phenomenon of the charge and discharge of the Leyden phial was 

 impossible. The lateral shock just adverted to, and observed by Wilson, was 

 almost a glaring instance of it; but a still more striking manifestation of the 

 theory of the Leyden phial was afforded by an experiment of Mr. Canton, who 

 showed that if a charged phial be insulated, the internal and external coat inns 

 would give alternate sparks, and then, by continuing the process, the phial 

 might be gradually discharged. Canton just touched on the discovery of dis- 

 simulated electricity. 



While these investigations were proceeding in England, the philosophers of 

 France were not wanting in that zeal and activity which they have always 

 manifested for the advancement of physical science. The Abbe Nollet, M. de 

 Monnier, and others, prosecuted similar experimental researches, and arrived 

 at the knowledge of several of the important circumstances developed in Eng- 

 land. Nollet showed that a phial containing rarefied air admitted of being 

 charged as readily as one which contained water, and stated that the water 

 in the Leyden experiment served no purpose except to conduct the electricity 

 to the glass. 



From this time to the period at which Dr. Franklin commenced his researches, 

 no important progress was made in the science, although at no former period 

 were experiments on so grand a scale projected and executed ; nor was public 

 attention ever before so powerfully attracted to any scientific subject. Nume- 

 rous and extensive experiments were made, both in England and France, to 

 determine the distance through which the electric shock could be transmitted, 

 the nature of the substances through which it could be propagated, and the 

 rate at which it moved. At Paris, M. Nollet transmitted it through a chain of 

 180 soldiers ; and at the convent of the Carthusians he formed a chain meas- 

 uring 5,100 feet, by means of iron wires extending between every two persons, 

 and the whole company gave a sudden spring, and sustained the shock at the 

 same instant. 



But it was in England that the experiments on this subject were made on 

 the most magnificent scale. Mr. Martin Folkes, then president of the Royal 

 Society, Lord Charles Cavendish, Dr. Bevis, and several other fellows of the 

 Society formed a committee to witness these experiments, the chief direction 

 and management of them being undertaken by Dr. Watson. A circuit was 

 first formed by a wire carried from one side of the Thames to the other over 

 Westminster bridge. One extremity of this wire communicated with the in- 

 terior of a charged jar ; the ether was held by a person on the opposite bank 



the river. This person held in his other hand an iron rod, which he dipped 

 into the river. On the other side, near the jar, stood another person, holding 

 in one hand a wire communicating with the exterior coating of the jar, and in 



