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1874 __ Musical or Harmonic Telegraph
Elisha Gray (1835-1901)
Comment : Elisha Gray knew how to generate and transmit sounds with electricity. Thus he asked himself : « can I transmit chords, for example, many notes, or signals, on a single telegraph line... » To demonstrate his ability to transmit chords, Elisha Gray built an 8 oscillator bank that can be controlled with a piano keyboard. Rapidly, the technical demonstrations attracted people interested in music. Thus, Gray developed a two octave version of the "harmonic telegraph" and toured the entire United States. The success of sound generation and transmission changed Gray's interests: instead of developing multiplex techniques, he became interested in sound and especially voice. Excerpt of the announcement of the concert at Highland Park, Chicago, on Dec. 29, 1874 : “The Blaney Lodge Quartette from Chicago [...] and other favorites vocalists, and a unique and extraordinary feature will be the first public exhibition of Elisha Gray’s Electric Telephone, by means of which, a number of familiar melodies, transmitted from a distance, through telegraphic wire, will be received upon violins and other instruments, within the room.”.Gray applied for a patent on a harmonic telegraph which consisted of multi-tone transmitters, each tone being controlled by a separate telegraph key. Gray gave several private demonstrations of this invention in New York and Washington, D.C. in May and June 1874. (Compiled from various sources)Gray claimed he got the first idea for using musical tones to send telegraph messages in 1867, when he was using a vibrating metal reed, or rheotome, in a circuit with an electromagnet and a telegraph key. When he closed the key, he “noticed a singing sound in the electromagnet, and by working the [telegraph] key as if transmitting a Morse message, the signals were audibly produced on the magnet by long and short sounds, representing the dots and dashes of the Morse alphabet”. Gray makes this sound like an entirely serendipitous experimental result, but by this time, he probably had heard of – and even seen demonstrated – the first telephone, constructed by Philip Reis in Germany in 1854. This device was designed to transmit musical tones. The transmitter consisted of a lever with a point, which rested on a membrane; when one sung a note, the membrane would cause the lever bounce, alternately making and breaking contact with a piece of platinum in the middle of the membrane. One story how the electric generation of sounds has been discovered deserves special attention. It was Pasteur who said that chance favors the prepared mind. In this case, a child’s game provided Gray with a mental model for a musical telegraph. In late January or early February of 1874 Gray heard the refrain of the rheotome issuing from his bathroom, where he found his young nephew ‘taking shocks’ to amuse the smaller children. With a vibrating rheotome in the circuit of a primary induction coil, the boy connected one end of the secondary coil to the zinc lining of the bathtub and held the other end in his hand. When the boy’s free hand glided along the bathtub lining, it produced a whining sound in tune with the rheotome. Gray tried the effect and found that quick, hard rubbing made the noise even louder than that of the rheotome itself. When he varied the pitch of the rheotome, the noise followed suit. Soon Elisha Gray improved his invention and replaced the bathroom with the body of a violin and a metal plate. He stated that the new “instrument” sounded in the range of the violin and the electric bathroom. In April of 1874 Gray attempted to patent a musical telegraph, which consisted of a two-tone transmitter, consisting of two single-pole electromagnets, each with a vibrating armature. Each armature made and broke contact with a platinum point which switched the current on and off to the coil. Because each electromagnet had a different electrical resistance, each electromagnet exerted a different magnetic pull on its armature and thus caused each armature to vibrate at a different frequency. Each coil and armature combination was controlled by its own telegraph key, so that each frequency could be sent separately or simultaneously. These electromagnets were connected to an induction coil which functioned like a modern transformer and stepped up the current before it was sent out onto the telegraph line. For the zinc bathtub, Gray substituted a grounded piece of galvanized tin. The patent drawing shows a man – presumably Gray himself – holding the wire from the coil in one hand and touching the tin with the other (Gray’s patent 166,096). The transmitter sent two different, audible tones which were reproduced on the tin plate receiver as the man rubbed it. The patent office initially rejected this application, on the grounds that one could not patent a circuit which included a person. So Gray converted the person into a slot into which he could substitute a variety of animal tissues, ranging from oyster shell to leather. He was eventually granted a patent in February of 1876. By then, Gray had moved on. He expanded his two-tone transmitter to a two-octave device that could send twenty-four different pitches (two octaves) over one telegraphic circuit. Each tone was generated by a single tone transmitter tuned to a different pitch. Gray often used several single tone transmitters inside more complex devices capable of sending multiple tones, such as his two octave transmitter and printing telegraph. Because he used the single tone transmitter by inserting it into slots in different inventions, it became one of Gray’s mechanical representations. Gray’s Musical Telegraph was able to play two octaves by having several single tone oscillators installed. Later models also had a simple tne wheel control. In 1874 Gray toured USA with his invention, and inspired Bell to design the Electric Harp for speech transmission over a phone line, using Gray’s instrument as blueprints. Since that time, Elisha Gray knew how to generate and transmit sounds with electricity. Thus he asked himself : “can I transmit chords, for example, many notes, or signals, on a single telegraph line…” To demonstrate his ability to transmit chords, Elisha Gray built an 8 oscillator bank that can be controlled with a piano keyboard. Rapidly, the technical demonstrations attracted people interested in music. Thus, Gray developed a two octave version of the “harmonic telegraph” and toured the entire United States. The success of sound generation and transmission changed Gray’s interests: instead of developing multiplex techniques, he became interested in sound and especially voice. In 1877 Elisha Gray organized probably the first concert of electronic music. Gray developed several receivers to take the place of the awkward animal tissue combination. His mental model was the telephone receiver developed by Philip Reis. According to Gray, the principle of the Reis receiver was that “when a coil of wire surrounding a bar of iron or the core of an electromagnet is traversed by an electric current, the said bar will be slightly elongated, and if these currents succeed each other with sufficient rapidity, a vibratory motion will be given to said bar, and it will give forth a musical tone.” All of Gray’s receivers embodied this principle and hence were capable of reproducing several tones simultaneously, but they employed different mechanical representations in the amplification of the vibrating core of the electromagnets. So while the Reis receiver functioned as Gray’s receiver mental model, these mechanical representations came from several other sources. For example, he used a variety of resonant cavities to amplify the sound. He got the idea of using a tin drum from a combination of the tin he used in his animal tissue patents and experiments with a violin with a metal plate on the back. His previous experience with using a bathtub as a receiver led him to substitute a wash basin. He systematically tested every type of receiver with his two-octave transmitter With these instruments Gray gave several impressive demonstrations in New York and Washington in May and June, 1874, after which he returned home to Chicago. (Compiled from various sources)“Recently certain users of telephones along the line of telegraph between New York and Boston have noticed a novel addition to the assortment of sounds which telephone wires pick up by induction from neighboring telegraph wires. The new sound is more musical than welcome, and is obviously made up of several distinct tones singing together, while each is independently interrupted by rapid breaks or short spaces of silence. These breaks correspond with the "dot and dash" sounds of the ordinary telegraphic instrument, so that the message may be spelled out by the interruptions of the singing tone. Tracing these sounds to their source, they are found to be due to a relatively new system of multiplex telegraphy now on trial on the Western Union Telegraph line between New York and Boston. The system is a development of Elisha Gray's original electro-harmonic or electro acoustic multiplex telegraph, the early history of which is familiar to all who are at all acquainted with the investigations which led to the invention of the first speaking telephone. The tones of the harmonic telegraph are produced by the vibration of steel reeds operated by electro-magnets, the pitch of the tone produced being determined by the number of vibrations the reed makes in a second. The current operating one reed , when passed over a line, will set in motion at the other end a reed exactly corresponding to the first in rate of vibration, and cause it to yield the same note, while a reed tuned to a different note is entirely unaffected. When two or more reeds are sounding separately or simultaneously at one end of a circuit, their counterparts at the other end will exactly respond, each singing or keeping silent as its corresponding vibrator at the other end of the wire is started or stopped. Obviously any interruptions of the current passing through any transmitting vibrator will be produced by its corresponding receiving instrument, but not by any other in the series, causing clearly recognizable breaks in the singing tone emitted by the vibrator. The message spelled out by such interruptions of the current may be read by the receiver in the interruptions of the tone, or the receiving vibrator may be used as a relay in operating an ordinary sounder. In the practical work, on the Boston line referred to, it has been found possible to send simultaneously by one wire, and analyze at the other end, four distinct tones, thereby transmitting four separate messages in one direction at one time. This offers a signal advantage over the quadruplex system, which transmits two separate messages simultaneously each, but cannot send four messages one way. In cases of extraordinary pressure of business the full capacity of the harmonic system may be utilized in either direction. It is hoped that the harmonic system will ultimately make possible the simultaneous sending of four or five messages both ways on a single wire; in other words, four tone messages and one ordinary Morse message in each direction, or ten in all. In this way all the tones in the octave will be made use of, and that is the probable limit of the system, unless it be found possible to operate with fractional tones.”. (From the "Brotherhood of Locomotive Engineers Monthly Journal", 1881)Elisha Gray's Multiple Harmonic Telegraph.Gray later claimed he got the first idea for using musical tones to send telegraph messages in 1867, when he was using a vibrating metal reed, or rheotome, in a circuit with an electromagnet and a telegraph key. When he closed the key, he "noticed a singing sound in the electro-magnet, and by working the [telegraph] key as if transmitting a Morse message, the signals were audibly produced on the magnet by long and short sounds, representing the dots and dashes of the Morse alphabet" (Gray, 1977). Gray makes this sound like an entirely serendipitous experimental result, but by this time, he probably had heard of -- and even seen demonstrated -- the first telephone, constructed by Philip Reis in Germany in 1854. This device was designed to transmit musical tones. The transmitter consisted of a lever with a point, which rested on a membrane; when one sung a note, the membrane would cause the lever bounce, alternately making and breaking contact with a piece of platinum in the middle of the membrane. This intermittent, on-off current would alternately magnetize and de-magnetize a receiving electromagnet, which would reproduce whatever tone had been sung into the membrane. The Reis apparatus was widely known at the time (1880). Gray later referred to his musical telegraph devices as telephones. Unlike Bell, Gray did not document his sources; therefore, it is hard to be sure where his background knowledge came from. Gray's next mental model for a harmonic telegraph came from observing his nephew touching a zinc-lined bathtub with one hand while in the other he held a coil connected to a vibrating rheotome, an electromagnetic device which produced a tone. When his nephew's hand glided along the zinc, Gray heard the bathtub emit the same tone as the rheotome. When Gray put himself in his nephew's position, he found he could alther the pitch and volume by changing the speed and pressure with which he rubbed the zinc. It was Pasteur who said that chance favors the prepared mind. In this case, a child's game provided Gray with a mental model for a musical telegraph. A single telegraph receiver could potentially reproduce multiple tones. He was so excited by the potential of this discovery that he resigned as superintendent of Western Electric to pursue his inventions full time. In April of 1874 Gray attempted to patent a musical telegraph, which consisted of a two-tone transmitter, consisting of two single-pole electromagnets, each with a vibrating armature. Each armature made and broke contact with a platinum point which switched the current on and off to the coil. Because each electromagnet had a different electrical resistance, each electromagnet exerted a different magnetic pull on its armature and thus caused each armature to vibrate at a different frequency. Each coil and armature combination was controlled by its own telegraph key, so that each frequency could be sent separately or simultaneously. These electromagnets were connected to an induction coil which functioned like a modern transformer and stepped up the current before it was sent out onto the telegraph line. For the zinc bathtub, Gray substituted a grounded piece of galvanized tin. The patent drawing shows a man -- presumably Gray himself -- holding the wire from the coil in one hand and touching the tin with the other (Gray's patent 166,096). The transmitter sent two different, audible tones which were reproduced on the tin plate receiver as the man rubbed it. (Michael E. Gorman)
French comment : L’histoire des instruments musicaux électroniques et celle de leurs inventeurs commence dès 1874 ! Elisha Gray, alors qu’il est sur le point d’inventer le téléphone, fait accidentellement vibrer sa baignoire par induction électromagnétique. Sa trop grande curiosité pour la musique le conduira à mettre au point le "télégraphe musical" avec lequel il se produira en concert, bien avant l’invention du haut parleur. (Compiled from various sources)Lorsque Elisha Gray présenta son télégraphe harmonique en 1874, il pensait que ce procédé pourrait être enfin la solution pour décongestionner le réseau télégraphique mondial et augmenter son rendement. Son projet était d’utiliser des fréquences musicales au lieu de simples impulsions. De simplement rythmique, le Morse devenait ainsi polyphonique, et il devenait possible de d’envoyer plusieurs messages [Gray pensait pouvoir transmettre jusqu’à 16 messages simultanément, mais le maximum atteint fut 8]. C’est d’ailleurs pour la promotion de son invention que Gray construisit un petit clavier contenant 16 oscillateurs électromagnétiques avec lequel il organisa de nombreux concerts, le clavier se trouvant soit dans la salle, soit « délocalisé » dans une autre ville. Et c’est en travaillant sur les moyens de transmettre des oscillations électriques qu’il découvrit accidentellement un moyen d’exciter des objets métalliques à ces fréquences, de manière à les rendre parfaitement audibles, inventant ainsi un premier type d’amplification et de haut-parleur. (Michel Risse, “À la recherche d’une genèse du son musical électronique : Les rapports entretenus entre musique et télécommunications avant 1900”, EMS Proceedings and Other Publications)On doit à M. Elisha Gray, ingénieur américain, d'un rare mérite, un moyen fort curieux de transmettre, à l'aide d'un seul fil, simultanément, sept à huit dépêches, et même le double de ce nombre, en employant le système duplex. Ce moyen, basé sur la loi du synchronisme des vibrations sonores propagées par les courants électriques, consiste à établir aux postes de départ et d'arrivée une série de diapasons, accordés deux par deux, et dont chaque groupe correspond à une échelle musicale. Ceci étant fait, si à l'un des deux postes, et à l'aide d'un électro-aimant et d'un circuit local, on vient à agir sur l'une des branches de l'un des diapasons, celui-ci étant relié au fil de ligne pourra, par une disposition spéciale, transmettre des ondes électriques, qui produiront dans la branche du diapason correspondant une série de vibrations, d'accord avec les premières. Les diapasons du départ étant donc reliés par groupes avec autant d'appareils manipulateurs, et ceux de l'arrivée avec un nombre égal d'appareils récepteurs, il est évident que les signaux transmis par les uns seront exactement reproduits par les autres. Le télégraphe harmonique de M. Élisha Gray a été soumis, en Amérique, pendant deux mois, sur la ligne de la Western-Union, entre Boston et New-York (320 kilomètres), à des expériences qui ont parfaitement réussi, et ont déterminé l'adoption, sur cette ligne, des systèmes de transmission rapide de M. Élisha Gray. Mais jusqu'ici l'Amérique seule l'a adopté. Dans une autre expérience, quatre employés, choisis parmi les meilleurs, ont envoyé en cinq heures 1,184 dépêches, soit 59 dépêches par employé et par heure. (Louis Figuier)Fin janvier-début février 1874, Gray fit une découverte accidentelle qui stimula ses recherches déjà très poussées sur la transmission du son.ou de ce qu'il appelait les courants «vibratoires». Le neveu de Gray jouait dans sa salle de bains avec l'un des appareils électriques de son oncle, s'amusant à «recevoir des décharges », comme il disait. Bien que les détails de cette découverte.appelée plus tard Γ« expérience de la baignoire».soient quelque peu fastidieux, il est aussi important de comprendre ce que Gray observa à cette occasion que de saisir ses liens avec les « autorités » du télégraphe. Le petit garçon s'amusait à prendre des décharges avec une de ces bobines d'induction ordinaires qui servent à interrompre le courant continu d'une pile pour le transformer en courant alternatif. Il avait connecté l'un des fils de la bobine au revêtement en zinc de la baignoire et tenait l'autre dans une main. Tandis qu'il promenait l'autre main sur le revêtement de la baignoire, Gray remarqua qu'un son se produisait sous cette main, son dont la fréquence semblait identique à celle de la partie vibrante de la bobine d'induction. Il prit la place de son neveu, changea la fréquence du dispositif vibrant et s'aperçut que la fréquence du son produit sous sa main avait également changé. «Voilà une expérience bien mystérieuse, dut alors se dire Gray : il s'y passe beaucoup de choses, mais à quoi peut-elle servir ? Qu'est-ce que cela peut bien vouloir dire ? » Gray se débattait avec ces questions le soir, chez lui, après sa journée de travail à la Western Electric. Durant près d'un mois, il fit toutes les expériences possibles sur le phénomène. Puis il conclut que celui-ci devait avoir de nombreuses applications dans la transmission et la réception télégraphiques de ces courants « vibratoires ». En l'espace de deux mois, il mit au point quatre dispositifs expérimentaux : deux transmetteurs et deux récepteurs. Il construisit, en effet, un transmetteur à un ton, version améliorée de l'interrupteur qui servit dans l'expérience de la baignoire ; ce dispositif transmettait un seul ton d'une fréquence donnée. Puis il modifia cette version et en fit un modèle capable de transmettre deux tons simultanément sur un même fil, modèle qu'il fit breveter. En outre, il conçut un récepteur-violon qui fonctionnait sur le principe de la baignoire. Et, surtout, il mit au point un récepteur électromagnétique muni d'un diaphragme métallique. En travaillant sur ces dispositifs, Gray découvrit qu'on pouvait «envoyer non seulement des tons simples, mais aussi des tons composés à travers le fil, et les recevoir, soit sur la plaque métallique [du récepteur-violon], soit sur l'aimant [du récepteur électromagnétique] ». C'était là une découverte importante, puisqu'elle permit à Gray de déduire que la télégraphie musicale, la télégraphie multiplex et la télégraphie de la voix étaient possibles. Il estima que c'était la transmission de la musique qui présenterait le moins de problèmes techniques, car son dispositif initial pouvait être connecté sans aucune modification de manière à former un dispositif simple de télégraphie musicale, c'est-à-dire que Gray pouvait prendre plusieurs transmetteurs à un ton réglés chacun sur une note différente de la gamme et les connecter, par exemple, à son récepteur électromagnétique. Il obtenait ainsi un système de télégraphie musicale semblable à un orgue électrique. En mai 1874, Gray fit la démonstration d'un nouvel appareil à Boston, New York et Washington, devant des personnalités du télégraphe et d'autres gens intéressés. Le compte rendu du New York Times paru le 10 juillet 1874 cite les paroles d'un responsable de la Western Union, Alfred Brown Chandler, spécialiste en électricité, qui voyait dans l'invention de Gray «la première étape vers l'élimination des instruments de manipulation... D'ici quelque temps, les opérateurs transmettront sur les fils le son de leur propre voix et se parleront au lieu de se télégraphier». Chandler était assez capable de rêver pour imaginer qu'on pût un jour parler avec de l'électricité, mais c'était aussi un télégraphiste.ou un expert.traditionnel et, à ce titre, il estimait que seuls les télégraphistes auraient les qualités requises pour se parler par fil. Cependant, l'article du Times fut violemment attaqué par l'une des revues professionnelles de la télégraphie, le Telegrapher, qui réimprima à cette occasion l'un de ses articles paru cinq ans plus tôt (en 1869) décrivant ce qu'il appelait un «téléphone» d'invention allemande. Selon cet article, le téléphone, dispositif permettant de transmettre la musique ou la parole, n'avait «aucune application pratique» et n'était qu'une «simple curiosité scientifique, certes très intéressante». Les rédacteurs du Telegrapher demandaient à Chandler et au New York Times s'ils «avaient jamais entendu parler de la vieille plaisanterie autrefois très répandue dans le milieu télégraphique, disant qu'on avait essayé une fois de parler entre New York et Philadelphie, mais qu'on avait dû abandonner car l'haleine de l'opérateur de Philadelphie empestait le whisky ! ». (David A. Hounshell, "Elisha Gray et le téléphone - à propos de l'inconvénient d'être un expert")
Source : Anonymous, “The Harmonic Telegraph”, From the "Brotherhood of Locomotive Engineers Monthly Journal", Volume 15, Number 3, March, 1881.
Source : Gorman, Michael E. (1998), “Transforming Nature”, Kluwer Academic Press, Chapter 3.
Source : Source: Figuier, Louis (1867-1891), "Supplément au Télégraphe Électrique", In "Les Merveilles de la Sciences ou Description des Inventions Scientifiques depuis 1870 - Supplément", Paris: Jouvet et Cie (Eds), pp. 523-603.
Urls : http://chem.ch.huji.ac.il/history/gray_elisha.html (last visited ) http://www.telegraph-office.com/pages/harmonic.html (last visited ) http://repo-nt.tcc.virginia.edu/book/chap3/chapter3sec4.html (last visited ) http://profiles.incredible-people.com/elisha-gray/ (last visited ) http://retiary.org/idea/idea2/idea/history/history.htm (last visited ) http://www.ems-network.org/spip.php?article165 (last visited ) http://documents.irevues.inist.fr/bitstream/handle/2042/30882/C%26T_1983_10_61.pdf?sequence=1 (last visited ) http://cnum.cnam.fr/CGI/fpage.cgi?P84.4/85/100/432/0/0 (last visited ) http://cnum.cnam.fr/CGI/fpage.cgi?P84.4/338/100/432/0/0 (last visited )

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