Figure 6o. — Bell's "harp" apparatus. From 

 G. Prescott, The Speaking Telephone, New York, 

 1878, p. 67. 



Bell had visited Joseph Henry at the Smithsonian 

 Institution and discussed with him some of the prob- 

 lems involved in the reproduction of sound. Bell 

 showed Henry how an empty coil might produce 

 audible sound, and Henry demonstrated a Reis 

 telephone to Bell.*' 



Some experiments that Bell performed in June 1875 

 indicated that his speculations of the previous summer 

 concerning a magneto telephone might be feasible 

 after all. During an attempt to send three messages 

 over his nrultiple telegraph. Bell found that one 

 magnetized reed could actuate another one without 

 a battery in the circuit. Thereupon Bell instructed 

 his associate, Thomas A. Watson,^" to make two 

 instruments, and to use in each instrument a magne- 

 tized reed attached to a membrane diaphragm. The 

 reed acted as an armature to an electromagnet, and 

 the electromagnet was in turn connected to another 

 similar instrument. But while sounds and changes 

 of pitch were audible in its receiver, this membrane 

 telephone (fig. 61) could not reproduce speech. 



In spite of its failure to transmit articulate speech, 

 Bell drew up patent specifications (fig. 62) for his 



49 United States Reports, 1887, vol. 126, pp. 1-584; Alexander 

 G. Bell, The Bell Telephone: The Deposition oj Alexander Graham 

 Bell in the Suit Brought by the United States to Annul the Bell Patents, 

 Boston, 1908; Catherine Mackenzie, Alexander Graham Bell: 

 The Man Who Contracted Space, Boston and New York, 1928; 

 F. L. Rhodes, Beginnings oj Telephony, New York, 1929; A. G. 

 Bell, U.S. patent 161739 (April 6, 1875). Many of Bell's 

 instruments for harmonic telegraphy and for telephony are 

 preserved in the Museum of History and Technology of the 

 Smithsonian Institution. The Reis instrument that Henry 

 showed Bell may be seen in the Museum {USNM 1S09T7). 



5" Thomas A. Watson, Exploring Life: The Autobiography of 

 Thomas A. Watson, New York and London, 1926. 



Figure 61. — Reproduction of Bell's diaphragm 

 magneto telephone of 1875. This model was 

 made under Bell's direction to serve as an 

 exhibit in one of the many patent trials in 

 which he was involved. {USNM 251533; 

 Smithsonian photo sg3io.) 



membrane telephone, and his patent was granted on 

 March 7, 1876. Among his claims, Bell included 

 the basic method of electrical telephony — electrical 

 currents repeating the wave forms of sounds — as well 

 as all instruments for producing these currents and 

 all instruments for reproducing sound from these cur- 

 rents. Bell's claims to the basic method of telephony 

 were so broad that they were attacked by some 600 

 patent suits, all of which were withstood. 



Bell and Watson were unable to reduce their 

 method to practice until a month after Bell had 

 applied for a patent on it, when Bell tried another 

 kind of transmitter. This transmitter was of a type 

 that modulated the current from a battery and was 

 similar to the one described above in the discussion 

 of Gray's caveat. On March 9, 1876, Bell's first 

 model of this instrument transmitted a few sounds 

 that were audible in a membrane receiver, and the 

 next day a better model (fig. 63) transmitted the 

 following famous words well enough to be understood: 

 "Mr. Watson, come here; I want you." This one 

 instrument that worked enabled Bell to modify his 

 others so they were all brought into operation. 



320 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



