Single-pole magneto telephone 



Figure 64. — Telephones exhibited by Alexander Graham Bell at the Philadelphia Centennial 

 Exposition of 1876. From The Bell Telephone: The Deposition of Alexander Graham Bell in the 

 Suit Brought by the United States to Annul the Bell Patents, Boston, igo8, pp. 97-100. 



PAPER 29: DEVELOPMENT OF ELECTRICAL TECHNOLOGY IN THE 19TH CENTURY: II 



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