Physics 525 



reasonable distance was possible. This system was the germ 

 of all modern telegraphy. At about the same time its devel- 

 opment in Europe began, but at first and for many years all 

 European systems were based on the phenomena discovered 

 by Oersted, the deviation of a needle on the passage of an 

 electric current through a conductor near and parallel to it. 

 While Henry was exhibiting his perfectly-conceived and well- 

 executed scheme for electric transmission to visiting friends, 

 Baron Schilling, a Russian Councillor of State, set up a 

 model of his proposed electric telegraph before the Emperors 

 Alexander and Nicholas, the first of the many " needle " sys- 

 tems which prevailed in Europe for many years, but which 

 were finally driven out by the superior merits of the American 

 system. Schilling's telegraph required thirty-six needles for 

 its operation, besides a complicated device for an audible 

 signal, to attract the attention of the operator. 



In connection with his study of magnets, Henry also de- 

 vised what is now generally known as a "relay," which is an 

 arrangement by means of which an electro-magnet operated 

 by one current is made to close the circuit of another bat- 

 tery, thus enabling a feeble magnet, requiring only a feeble 

 current, to set into operation another, at any point in the 

 circuit. Thus he had evolved all the essentials of a complete 

 telegraph system, lacking only mechanical details which en- 

 gineering skill and ingenuity might easily have supplied. 



Had Henry been less a lover of pure science, or had his 

 commercial instinct been more highly developed, the Albany 

 Academy mile of wire would have grown into the telegraph 

 system of America, instead of furnishing, as it unquestionably 

 did ten years later, the principle upon which that system was 

 founded. It has required a good many years to dispel certain 

 illusions concerning the electric telegraph to which Ameri- 

 cans were inclined to cling, but it is now tolerably well known 

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