PROGRESS IN ELECTRICITY 



constantly employed by the various writers of that 

 day. Among these writers was the English scientist 

 William Watson, who was not only a most prolific 

 writer but a tireless investigator. Many of the words 

 coined by him are now obsolete, but one at least, "cir- 

 cuit," still remains in use. 



In 1746, a French scientist, Louis Guillaume le 

 Monnier, had made a circuit including metal and water 

 by laying a chain half-way around the edge of a pond, 

 a man at either end holding it. One of these men 

 dipped his free hand in the water, the other presenting 

 a Ley den jar to a rod suspended on a cork float on the 

 water, both men receiving a shock simultaneously. 

 Watson, a year later, attempted the same experiment 

 on a larger scale. He laid a wire about twelve hun- 

 dred feet long across Westminster Bridge over the 

 Thames, bringing the ends to the water's edge on the 

 opposite banks, a man at one end holding the wire and 

 touching the water. A second man on the opposite side 

 held the wire and a Ley den jar; and a third touched 

 the jar with one hand, while with the other he grasped 

 a wire that extended into the river. In this way they 

 not only received the shock, but fired alcohol as readily 

 across the stream as could be done in the laboratory. 

 In this experiment Watson discovered the superiority 

 of wire over chain as a conductor, rightly ascribing 

 this superiority to the continuity of the metal. 



Watson continued making similar experiments over 

 longer watercourses, some of them as long as eight 

 thousand feet, and while engaged in making one of these 

 he made the discovery so essential to later inventions, 

 that the earth could be used as part of the circuit in 



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