Figure 58. — Reproductions of Gray's telephone transmitter 

 and receiver of 1876. (USNM J0821 1 , 308312; Smithsonian photo 

 17204.) 



of acidulated water so that when sound entered the 

 cylinder, its diaphragm vibrated and moved the wire 

 attached to it up and down in the liquid. If the liquid 

 and the wire were made part of an electrical circuit 

 with a battery and a Gray receiver, the varying liquid- 

 wire contact would modulate the current produced 

 by the battery, and the receiver would reproduce this 

 modulation in the form of sound. 



In January 1876 Gray went to Washington to 

 patent some further improvements on his harmonic 

 telegraph and while there drew up a caveat for his 

 method of transmitting and reproducing speech 

 (fig. 58). This caveat was filed on February 14, 

 1876.« 



Gray did not test one of his liquid transmitters 

 until he attended the Philadelphia Centennial Ex- 

 position in July 1876 as one of the judges of the 

 electrical exhibits. He had a transmitter made and 



■" George B. Prescott, The Speaking Telephone, Talking Phono- 

 graph and Other Novelties, New York, 1878, pp. 202-205. 



demonstrated it to some of his friends who were in 

 attendance at the exposition. 



On the same day that Gray applied for a caveat 

 on the transmission of speech, another inventor 

 applied for a patent on an invention having the 

 same purpose. This other invention received U.S. 

 patent 174465, a number which came to represent 

 one of the most valuable patents ever issued. The 

 man who applied for and received this patent was 

 Alexander Graham Bell. 



Bell, born in Scotland in 1847, had emigrated to 

 Canada with his parents. He had followed in his 

 family's tradition of studying human speech and 

 acoustics, and before he left Edinburgh in 1870 he 

 had begun the study of Helmholtz's Die Lehre der 

 Tonempfindungen. Sometime between 1867 and 1870 

 further study of the apparatus described in this 

 work — in particular of the tuning forks that were 

 driven by an electromagnet — suggested to him the 

 possibility of a harmonic multiple telegraph. In the 

 fall of 1872, after he had moved from Braritford, 



318 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



