6 PROCEEDINGS OF THE AMERICAN ACADEMY 



currents induced in the secondary wires. A rheotome was placed in 

 circuit with the thick wires of a Ruhmkorff's coil, and the fine wires 

 were connected with two strips of brass (A and B), insulated from one 

 another by means of a sheet of paper. Upon placing the ear against 

 one of the strips of brass, a sound was perceived like that described 

 above as proceeding from an empty helix of wire during the passage of 

 an intermittent voltaic current. A similar sound, only much more 

 intense, was emitted by a tin-foil condenser when connected with the 

 fine wires of the coil. 



One of the strips of brass, A (mentioned above), was held closely 

 against the ear. A loud sound came from A whenever the slijs B was 

 touched with the other hand. It is doubtful in all these cases whether 

 the sounds proceeded from the metals or from the imperfect conductors 

 interposed between them. Further experiments seem to favor the 

 latter supposition. The strips of brass A and B were held one in each 

 hand. The induced currents occasioned a muscular tremor in the 

 fingei'S. 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 e.ar, but heard nothing. I 

 requested him to hold the strips A and B himself. He was then dis- 

 tinctly conscious of a noise (which I was unable to jierceive) proceed- 

 ing from his finger. In these cases a portion of the induced currents 

 passed through the head of the observer when he placed his ear against 

 his own finger ; and it is possible that the sound was occasioned 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 

 other a loud sound comes from the parts in contact. When the arm 

 of one is placed against the arm of the other, the noise produced can be 

 heard at a distance of several feet. In all these cases a slight shock 

 is experienced so long as the contact is preserved. The introduction 

 of a piece of paper between the parts in contact does not materially 

 interfere with the production of the sounds, while the unpleasant 

 effects of the shock are avoided. 



When a powerful current is passed through the body, a musical note 

 can be perceived when the ear is closely applied to the arm of the 

 person experimented upon. The sound seems to proceed from the 

 muscles of the fore-arm and from the biceps muscle. The musical 

 note is the unison of the rheotome employed to interrupt the primary 



