Figure 75. — Commercial type of Blake Telephone transmitter. 

 From Scientific American, 1879, ^°^- 4'; P- 274. 



patents on their own transmitters. A long period 

 of litigation ensued, which lasted until 1903. 



Emile Berliner,'''' a German immigrant who had 

 come to the United States in 1870, spent his spare 

 time experimenting with electricity. On April 14, 1877, 

 Berliner filed a caveat on a metal-to-metal imperfect 

 contact transmitter (fig. 69) that was similar to that 

 of the Reis telephone but of a more sturdy construc- 

 tion. In this transmitter, modulation was achieved 

 by the variable resistance of the imperfect contact. 

 After applying for a patent on this device on June 4, 

 1877 (U.S. patent 463569, November 17, 1891), 

 Berliner sold his patent rights to the Bell Company. 

 While few commercial instruments were manufac- 

 tured on the basis of the Berliner patent, it was useful 



5< Frederic W. Wile, Emile Berliner; Malcer of the Microphone, 

 Indianapolis, 1926. Many of Berliner's instruments are pre- 

 served in the Museum of History and Technology of the 

 Smithsonian Institution. 



to the Bell Telephone Company in establishing 

 claims to patent priority. 



Thomas A. Edison was a well-known telegraph 

 inventor whose ability to invent "to order" was 

 exploited on several occasions during the struggle 

 for control of the remunerative telephone patents. 

 Edison had worked on the harmonic multiple tele- 

 graph, and much of his work ran parallel with that 

 of Bell and Gray. In 1875 he devised an electro- 

 magnetic receiver similar to the receivers of Bell and 

 Gray, and he subsequently found that this receiver 

 could be used as part of a magneto telephone. Edi- 

 son started his work in telephony in 1876, trying to 

 change Reis' telephone into a commercial device by 

 modifying the contacts. Edison obtained some suc- 

 cess in this experimentation by placing a drop of 

 water between the contacts; however, it was not until 

 the spring of 1876, after replacing Reis' metallic 

 contacts by semiconducting ones, that he was • able 

 to transmit sentences. In January 1877 Edison fur- 



328 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



