Bell's Telephonic Researches 



passage of reversed intermittent currents through 

 the human body. A breaker was placed in 

 circuit with the primary wires of an induction 

 coil, and the fine wires were connected with two 

 strips of brass. One of these strips was held 

 closely against the ear, and a loud sound pro- 

 ceeded from it whenever the other slip was 

 touched with the other hand. The strips of 

 brass were next held one in each hand. The 

 induced currents occasioned a muscular tremor 

 in the fingers. Upon placing my forefinger to my 

 ear a loud crackling noise was audible, seemingly 

 proceeding from the finger itself. A friend who 

 was present placed my finger to his ear, but heard 

 nothing. I requested him to hold the strips 

 himself. He was then distinctly conscious of a 

 noise (which I was unable to perceive) proceed- 

 ing from his finger. In this case a portion of the 

 induced current passed through the head of the 

 observer when he placed his ear against his own 

 finger, and it is possible that the sound was oc- 

 casioned by a vibration of the surfaces of the ear 

 and finger in contact. 



When two persons receive a shock from a 

 Ruhmkorff's coil by clasping hands, each taking 

 hold of one wire of the coil with the free hand, a 

 sound proceeds from the clasped hands. The 

 effect is not produced when the hands are moist. 

 When either of the two touches the body of the 

 pther a loud sound comes from the parts in con- 

 tact. When the arm of one is placed against the 

 arm of the other, the noise produced can be heard 

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