Masterpieces of Science 



thought that the change of the density of the 

 current at the receiving end would cause the 

 magnet there to attract the reed A' in such a 

 manner that it should copy the motion of the 

 reed A, in which case its movements would oc- 

 casion a sound from the membrane n r similar 

 in timbre to that which had occasioned the origi- 

 nal vibration. 



Fig. 7 



The results, however, were unsatisfactory and 

 discouraging. My friend, Mr. Thomas A. Wat- 

 son, who assisted me in this first experiment, 

 declared that he heard a faint sound proceed 

 from the telephone at his end of the circuit, but I 

 was unable to verify his assertion. After many 

 experiments, attended by the same only partially 

 successful results, I determined to reduce the 

 size and weight of the spring as much as possible. 

 For tin's purpose I glued a piece of clock spring 

 about the size and shape of my thumb nail, 

 firmly to the centre of the diaphragm, and had 

 a similar instrument at the other end (Fig. 8) ; 

 we were then enabled to obtain distinctly audi- 

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