Sunday, February 11, 2007

Timeline of the telephone (1849-1875)

1849 Antonio Meucci demonstrates a device later called a telephone to individuals in Havana. (It is disputed if this is an electric telephone, but is said to involve direct transmission into the body.)
1854 Charles Bourseul publishes a description of a make-break telephone transmitter and receiver but does not construct a working instrument.
1854 Antonio Meucci demonstrates an electric voice operated device in New York, but it is not clear what kind of device he demonstrated.
1860 Johann Philipp Reis demonstrates a make-break transmitter after the design of Bourseul and a knitting needle receiver. Witnesses said they heard human voices being transmitted.
1861 The German Philipp Reis manages transfer voice electrically over a distance of 340 feet, see Reis' telephone.
1864 In an attempt to give his musical automaton a voice, Innocenzo Manzetti invents the 'Speaking telegraph'. He shows no interest in patenting his device, but it is reported in newspapers.
1865 Meucci reads of Manzetti's invention and writes to the editors of two newspapers claiming priority and quoting his first experiment in 1849. He writes "I do not wish to deny Mr. Manzetti his invention, I only wish to observe that two thoughts could be found to contain the same discovery, and that by uniting the two ideas one can more easily reach the certainty about a thing this important." If he reads Meucci's offer of collaboration, Manzetti does not respond.
1871 Antonio Meucci files a patent caveat (a statement of intention to patent).
1872 Elisha Gray founds Western Electric Manufacturing Company.
1872 Prof Vanderwyde demonstrated Reis's telephone in New York.
July 1873 Thomas Edison notes variable resistance in carbon grains due to pressure, builds a rheostat based on the principle but abandons it because of its sensitivity to vibration.
May 1874 Gray invents electromagnet device for transmitting musical tones. Some of his receivers use a metallic diaphragm.
December 29, 1874 Gray demonstrates his musical tones device and transmitted "familiar melodies through telegraph wire" at the Presbyterian Church in Highland Park, Illinois.
2 June 1875 Alexander Graham Bell transmits the sound of a plucked steel reed using electromagnet instruments.
1 July 1875 Bell uses a bi-directional "gallows" telephone that was able to transmit "indistinct but voicelike sounds" but not clear speech. Both the transmitter and the receiver were identical membrane electromagnet instruments.
1875 Thomas Edison experiments with acoustic telegraphy and in November builds an electro-dynamic receiver but does not exploit it.