1854 __ String telephone or lover’s telegraph
‣ Comment : Credited to Amos E. Dolbear in 1854, the "string telephone", pr "lover's telegraph", was undoubtedly inspired by Wheatstone's experiments. in this device, a string or wire is stretched between the closed ends of two cylindrical containers. Speaking into the open end of one container sends the voice vibrations over the string or wire to the distant container. In later years, children often made these telephones from discarded tin cans, hence the name "tin can telephone". By making the connecting link a taut metallic wire, carefully supported, ranges up to a quarter mile could be achieved. As made by children, the tin can telephones always seemed to work. Possibly this was because over the short distances usually involved, the shrill voices of the users could normally be heard with or without the telephone. (Lewis Coe, 1995, "The telephone and its several inventors : a History", Jefferson NC : MacFarland & Co, 2006, p. 41) — Amos Emerson Dolbear invented the string telephone this year. This device was never patented, and apparently re-invented about 25 years later, patented, and used commercially in Murray, Kentucky. In 1864, Professor Amos E. Dolbear invented a 'talking machine'. The model was lost and the device forgotten. It was said to be basically the same as the Bell telephone exhibited in 1876 at the Philadelphia Centennial Exposition. In 1876, Professor Amos E. Dolbear of Tufts College began experiments on the speaking telephone in August of this year. By autumn, he had come up with the idea of using a permanent magnet in the receiver. The same instrument could be used for sending or receiving. Although it was somewhat like Bell's first telephone, it required no battery. (Timeline of Related Developments, insulators.com). — Amos Emerson Dolbear (November 10, 1837 – February 23, 1910) was an American inventor. In 1853 he invented the string telephone, and in 1864 the electric writing telegraph. By 1876 he had devised a telephone operating on the same principle as Bell's. His patents interfered with Guglielmo Marconi's planned activities in the US. He invented the first telephone receiver with a permanent magnet in 1865, 11 years before Alexander Graham Bell patented his model. Later, Dolber couldn't prove his claim, so Bell kept the patent. In 1882 Professor Amos E. Dolbear was able to communicate over a distance of a quarter of a mile without wires. It is interesting to note that the Tufts Professor was ahead of Hertz and Marconi. (marconi first let'er rip in 1895) He received a U.S. patent for a wireless telegraph in March of that year. His device relied on induction, not RF. His set-up used phones grounded by metal rods poked into the earth. His transmission range was a little less than a mile, but he received a patent for it (U.S. Patent No. 350,299). But more importantly the Dolbear patent prevented the Marconi Company from operating in the United States. In the end Marconi had to purchase Dolbears patent, even though it was A. generally inferior and B. untractable in application. In 1868 Dolbear (while a professor at Bethany College) invented the electrostatic telephone. Dolbear also work on converting sound waves into electrical impulses. He also invented the opeidoscope, and a system of incandescent lighting. He authored several books, articles, and pamphlets, including "Matter, Ether, Motion," and was recognized for his contributions to science at both the Paris Exposition in 1881 and the Crystal Palace Exposition in 1882. (Compiled from various sources)
‣ Source : Coe, Lewis (1995), "The telephone and its several inventors : a History", Jefferson NC : MacFarland & Co, 2006, p. 41.
‣ Source : Du Moncel, Theodore (1881), “Les progrès de la téléphonie”, extrait d’une conférence faite à l’Exposition d’Électricité le 25 octobre 1881, In "La Lumière Électrique — Journal Universel d'Électricité", 1e série, vol. 5, n°53-78, 1881, Paris : Union des syndicats de l'électricité, 2 novembre 1881, No. 62, pp. 165-169.
‣ Source : Du Moncel, Theodore (1881), “Les progrès de la téléphonie”, extrait d’une conférence faite à l’Exposition d’Électricité le 25 octobre 1881, In "La Lumière Électrique — Journal Universel d'Électricité", 1e série, vol. 5, n°53-78, 1881, Paris : Union des syndicats de l'électricité, 5 novembre 1881, No. 63, pp. 184-186.
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