OF ARTS AND SCIENCES. 5 



lions of the current are timed to its movements. For instance, present 

 an electro-magnet to the strings of a piano. It will be found that the 

 etrinjj which is in unison with the rheotome included in the circuit 

 will be thrown into vibration by the attraction of the magnet. 



liehnholtz,* in his experiments upon the synthesis of vowel sounds 

 caused continuous vibration in tuning-forks which were used as the 

 armatures of electro-magnets. One of the forks was employed as a 

 rheotome. Platinum wires attached to the prongs dipped into mer- 

 cury. 



The intermittent current occasioned by the vibration of the fork 

 traversed a circuit containing a number of electro-magnets between 

 the poles of which were placed tuning-forks whose normal rates of 

 vibration were multiples of that of the transmitting fork. All the 

 forks were kejjt in continuous vibration by the passage of the inter- 

 rupted current. By re-enforcing the tones of the forks in different 

 degrees by means of resonators, Helmholtz succeeded in reproducing 

 artificially certain vowel sounds. 



I have caused intense vibration in a steel strip, one extremity of 

 which was firmly clamped to the pole of a U-shaped electro-magnet, the 

 free end overhanging the otlier pole. The amplitude of the vibration 

 was greatest when the coil was removed from the leg of the magnet to 

 which the armature was attached. 



7. All the effects noted above result from rapid interruptions of a 

 voltaic current, but sounds may be produced electrically in many other 

 ways. 



The Canon Gottoin de Coma,t in 1785, observed that noises were 

 emitted by iron rods placed in the open air during certain electrical 

 conditions of the atmosphere ; Beatson $ produced a sound from an 

 iron wire by the discharge of a Leyden jar; Gore § obtained loud 

 musical notes from mercury, accompanied by singularly beautiful cris- 

 pations of the surface during the course of experiments in electrolysis ; 

 and PagH || produced musical tones from Trevelyan's bars by the action 

 of the galvanic current. 



8. When an intermittent current is passed through the thick wires 

 of a Ruhmkorff's coil, very curious audible effects are produced by the 



* Helmholtz. Die Lelire von dem Tonempfindungen. 



t See " Treatise on Electricity," by De la Rive, I., p. 300. 



X Ihid. 



§ Gore. Proceedings of "Royal Society, XII., p. 217. 



II Page. " Vibration of Trevelyan's bars by the galvanic current." SiUi- 

 man's Journal, 1850, IX., pp. 105-108. 



