Reis' telephone

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Reis' telephone, an invention by Philipp Reis by an inspiration from a French article in 1854 (by Bourseul) how to create a microphone-like devices. His first successful work was achieved in October 1861. In 1862, Reis demonstrated his telephone to Wilhelm von Legat, Inspector of the Royal Prussian Telegraph Corps who produced an account of this (Legat, 1862), a translation of which came to Thomas Edison in 1875 and was used in Edison's successful development of the carbon microphone. (The Legat account includes drawings that are different from the one below suggesting that it is of a later version.) Edison acknowledged his debt to Reis:

The first inventor of a telephone was Phillip [sic] Reis of Germany only musical not articulating. The first person to publicly exhibit a telephone for transmission of articulate speech was A. G. Bell. The first practical commercial telephone for transmission of articulate speech was invented by myself. Telephones used throughout the world are mine and Bell's. Mine is used for transmitting . Bell's is used for receiving. (Edison 2006, [LB020312 TAEM 83:170]

Microphone (I) Reis created this using a tensed circular swine-intestine membrane, with a small platinum brick mounted in its centre. Another platinum rod with a nail-like pin in one of its end, rested against the center-brick. Vibrations in the membrane caused the pin to temporary open and close the circuit, thus converting vibrations in the air into electrical signal. This is called a "Make-Break" transmitter, and is capable only of low-fidelity transmission of sound. With careful adjustment, this transmitter is capable of operating in a "loose contact variable pressure" or microphone mode, but Reis was unaware of that prior to his death, and always described the transmitter as "make break". If the platinum contacts are replaced with carbon, this microphone is no different from any other loose contact variable pressure microphone.

Loudspeaker (II) Reis' speaker worked by magnetostriction. In his first receiver he wound a coil of wire around an iron knitting needle and rested the needle against the "F" hole of a violin. As current passed through the needle, the iron shrank and a click was formed. The image shown below is a more advanced version where the iron bar is clamped to a cigar box shaped resonator. This receiver is very insensitive; it produces weak sound but has good fidelity. It requires very high current and is a current sensitive device rather than a voltage sensitive device.

Reis was marginally successful. This instrument could transmit continuous musical tones but produced indistinct speech.

References

Edison, Thomas A. 2006. The Edison Papers, Digital Edition. Rutgers University, [cited 26 March 2006]. Available from http://edison.rutgers.edu/.

Legat, V. 1862. Reproducing sounds on extra galvanic way [cited 26 March 2006]. Available from http://edison.rutgers.edu/NamesSearch/DocImage.php3?DocId=TI2459&.

Friedrich Georg Wieck, Otto Wilhelm Ålund "Uppfinningarnas bok" vol. II, 1874.

Thompson, Sylvanus P. "Philipp Reis, Inventor of the Telephone" London: E. & F.N. Spon, 1883.

Coe, Lewis "The Telephone and Its Several Inventors: A History" Chapter 2, McFarland & Co, 1995.

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Reis' telephone

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References