. Bulletin. Science. A^B_ Fi^.S. ^'3:/. Figure 62.—Drawings from Bell's famous patent of 1876, showing how his invention could be used to transmit and receive both continuous and dis- continuous sound waves. From patent 174465 (March 7, 1876). Bell's backers deemed his progress sufficient for a demonstration in June 1876 of several forms of his membrane telephone (fig. 64) together with his multiple telegraph at the Philadelphia Centennial Exposition. It was at this exposition that the famous Dom Pedro incident occurred, which is now so familiar that it need not be repeated again. Bell wa
. Bulletin. Science. A^B_ Fi^.S. ^'3:/. Figure 62.—Drawings from Bell's famous patent of 1876, showing how his invention could be used to transmit and receive both continuous and dis- continuous sound waves. From patent 174465 (March 7, 1876). Bell's backers deemed his progress sufficient for a demonstration in June 1876 of several forms of his membrane telephone (fig. 64) together with his multiple telegraph at the Philadelphia Centennial Exposition. It was at this exposition that the famous Dom Pedro incident occurred, which is now so familiar that it need not be repeated again. Bell was so discouraged, however, by the poor efficiency of his membrane telephones that he felt it necessary to drop work on his multiple telegraph in order to devote all his time to the telephones. They would work moderately well over a short line, but the apparatus was delicate and did not articulate sounds distinctly enough for practical use. Bell never eliminated the necessity of shouting into his magneto telephone, but he did succeed in improving it somewhat. Early in October of 1876 Bell replaced the steel reed that he had been using on the membrane by a steel plate almost as large as the membrane and glued to it. About the same time Watson re- placed the soft iron core of the electromagnet with a compound permanent magnet. After these changes were made. Bell and Watson tested the new apparatus between two rooms in the building where their laboratory was located and found they had no dif- ficulty in carrying on a "sustained ; On October 9, 1876, "sustained conversation was successfully carried on for the first time upon a real line several miles in ; These improvements inspired Bell a week later to replace the membrane by an all-metal diaphragm clamped around the edge. After placing the resulting structure in a box as large as a professional photog- rapher's camera of the time. Bell and Watson tested this "box" telephone (fig.
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Keywords: ., bookauthorunitedstatesdepto, bookcentury1900, booksubjectscience
