Bell. Alexander Graham. The Second Bell Telephone Patent. Improvements in Electric Telephony. U.S. Patent No. 186,787 , issued on January 15, 1877. 4to. 3 pp., 2 p. of illustrations and diagrams. P. Norris, Photo-Lithographer, Washington D.C. on illustrations, letterpress on patent text.ONE OF BELL’S TWO FUNDAMENTAL PATENTS FOR THE TELEPHONE. Prior to this patent, and after the first patent in 1876, Bell continuously worked on improving the sound and transmission quality of the telephone. As he was able to demonstrate single direction communication over distance in early 1876, by the end of the year Bell performed the first two-way communication via the telephone. This patent details the movement of sound along several devices to the intended receiving device, inadvertently necessitating the need for the telephone exchange or switchboard. Along with Bell's first patent for the telephone issued in March of 1876, this second patent allowed for the domination of the Atlantic Telephone and Telegraph company in the markets and the courts. This second patent insured that no telephone in the United State would be free of Bell’s legal claims until its expiration on February 1st, 1894.“In this patent, [Bell] explicitly laid out a system of “electric telephony” and described his working telephone, now vastly more practical than the flimsy device sketched in the first grant. The receiver contained a permanent electromagnet that vibrated a metallic “armature”, or diaphragm, to produce a sound corresponding to that made at the transmitter. The magneto would remain the basic principle of the telephone receiver for decades.” (Beauchamp 46-7).

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