DEVELOPMENT OF TELEPHONE SERVICE 427 



pitch, strength and quality unchanged; the comprehensive scope of the 

 newly-created art of speech transmission; the remarkable transmitting 

 qualities of the first of all electric-speaking telephones ; and the prompt- 

 ness with which the inventor placed before the public a full and com- 

 plete knowledge of his invention and of the essential steps leading to 

 his application for letters-patent, all go to prove the possession in. 

 187-1—6 of an unusual knowledge on the part of Alexander Graham 

 Bell, the more remarkable in view of the slight grasp electricians then 

 possessed of magnetic action and the interrelation of the magnetic 

 field and the electric current. 



II. The Telephone Exhibit at the Centennial Exposition 



In 1874, Alexander Graham Bell evolved his magnificent concep- 

 tion of the transmission of speech over long distances by means of the 

 electric-speaking telephone. Theoretically it was perfect; practically 

 it had no tangible existence. Men eminent in their respective pro- 

 fessions, to whom he confided his plans in the autumn of 1874, ad- 

 mitted that while in theory the undulating-current method ' was ade- 

 quate to the transmission of speech,' yet the electrical effect produced 

 by the vibration of a diaphragm-armature actuated only by the human 

 voice ' Avould be entirely too small to accomplish the desired end.' In 

 fact, so complete was the absence of practical knowledge concerning 

 the electrical effect that would be produced by causing the spoken word 

 to vibrate an armature in front of an electro-magnet that the experts, 

 most competent to pass upon the value of such an invention as the 

 electric-speaking telephone, testified that the state of the art was such 

 at the date of the patent that it could hardly have been supposed that 

 a magneto-generator moved by a force so slight as the spoken word, 

 ' would nnder any circumstances be able to generate an electric cur- 

 rent which would produce upon a receiving instrument any effect what- 

 ever which would be perceptible to the senses.' 



Discouraging though the advice and the suggestions of his friends 

 proved, and disheartened though he was by ill-health and the lack of 

 funds to carry on his telephone experiments, never did the inventor 

 allow aught to divert his firm purpose of transforming that marvelous 

 theory into a tangible speech-transmitting telephone. 



In 1874, Alexander Graham Bell occupied the chair of vocal physiol- 

 ogy in the Boston University, and supplemented his lectures ' by ex- 

 perimental demonstration of the practicability of correcting stammer- 

 ing, stuttering, lisping, burring and other defects of speech.' To a 

 class composed exclusively of teachers of the deaf who had been sent 

 to Boston by various institutions for the deaf throughout the United 

 States, he delivered courses of lectures upon the subject of teach- 

 ing articulation to deaf pupils, experimentally demonstrating his 

 methods by giving instruction to deaf-mutes. He also had a class of 



