264 PLEASANT IV A YS IN SCIENCE. 



intermittent current resulting from the tatter's vibiations. 

 So that, if there were several transmitting forks, each could 

 send its own message at the same time, each receiving fork 

 responding only to the vibrations of the corresponding trans- 

 mitting fork. La Cour proposed, in fact, that his instrument 

 should be used in combination with other methods of tele- 

 graphic communication. Thus, since the transmitting fork, 

 whenever put in vibration, sets the local battery of the 

 receiving station at work, it can be used to work a Morse 

 instrument, or it could work an ordinary Wheatstone and 

 Cook instrument, or it could be used for a pantelegraph. 

 The same wire, when different forks are used, could work 

 simultaneously several instruments at the receiving station. 

 One special use indicated by La Cour was the adaptation of 

 his system to the Caselli pantelegraph, whereby, instead of 

 one style, a comb of styles might be carried over the trans- 

 mitting and recording plates. It would be necessary, in all 

 such applications of his method (though, strangely enough, 

 La Cour's description makes no mention of the point), that 

 the vibrations of the transmitting fork should admit of being 

 instantly stopped or " damped" 



Mr. Gray's system is more directly telephonic, as aiming 

 rather at the development of sound itself than at the trans- 

 mission of messages by the vibrations corresponding to 

 sound. A series of tuning-forks are used, which are set in 

 separate vibration by fingering the notes of a key-board. 

 The vibrations are transmitted to a receiving instrument 

 consisting of a series of reeds, corresponding in note to the 

 series of transmitting forks, each reed being enclosed in a 

 sounding-box. These boxes vary in length from two feet to 

 six inches, and are connected by two wooden bars, one of 

 which carries an electro-magnet, round the coils of which 

 pass the currents from the transmitting instrument When 

 ^ tuning-fork is set in vibration by the performer at the 

 transmitting key-board, the electro-magnet is magnetized 

 and demagnetized synchronously with the vibrations of the 

 fork. Not only are vibrations thus imparted to the reed of 



