OF ARTS AND SCIENCES. 273 



III. As the same kind of motion, due to change of form, is taking 

 place when a ring is vibrating at its harmonic rate, producing what we 

 call sound vibrations, it was thought probable that a magnetized ring, 

 having a coil of wire about it in connection with a telephone, would 

 set up vibratory currents when it was struck ; and this was found to 

 be true, for when the coil containing the heavy iron core was put in 

 circuit with a telephone in another room, the sound of the stroke and 

 the pitch of the ring could jjlaiuly be heard. In the first case, the 

 number of turns of wire was small, perhaps fifty or thereabouts. I 

 therefore had two larger rings made, each about one foot in diameter 

 and half an inch thick. 



IV. One of these was wound with six or seven hundred turns of 

 No. 32 wire. Before it was magnetized, it was connected with the 

 telephone, and tested for its magnetic condition by striking. The ring 

 could plainly be heard, which showed that it had some degree of 

 magnetism. 



V. Then about two hundred turns of coarse wire were wound upon 

 it, and a strong current sent through it to magnetize it. After this 

 magnetizing coil had been removed, the nng was again tested as in IV. 

 The sound was very much louder. Indeed, the telephone could be 

 held a foot from the ear and be heard. 



VI. With the ring in V. still in circuit, the companion ring, with- 

 out any wire upon it, was brought near it and struck. The sound was 

 easily heard in the telephone circuit. 



VII. This second ring was now magnetized in the same way as 

 the first, when the magnetizing helix was removed, and experiment 

 VI. repeated. The sound was very much louder. 



VIII. The ring was now struck and moved away from the first ring 

 by stages of an inch or two at a time. It was found possible to hear 

 its pitch in the second circuit, wiien it was a yard or more away 

 from it. 



IX. As the pitch of the two rings was not quite the same, the 

 higher one was loaded so as to bring them to unison. The sound was 

 then louder and more persi.stent than before. This gave evidence that 

 it was a case of sympathetic vibration, while the former were forced 

 vibrations. 



X. A common horseshoe permanent macrnet, with legs about six 

 inches long, had perhaps fifty ohms of No. 32 wire wound about the 

 bend, and this was put in circuit with the telephone, and struck like 

 a tuning fork. The sound in the telephone was remarkably loud, 

 indeed too strong to be held comfortably at the ear. 



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