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| Gray's harmonic telegraph apparatus follows in the track of Reis and Bourseul — that is to say, the interruption of the current by a vibrating contact. Gray recognized the lack of fidelity of the make-break transmitter, and reasoned by analogy with the lovers telegraph that if the current could be made to model more closely the movements of the diaphram rather than simply turning the circuit on and off, a greater fidelity might be achieved. Gray built and patented a liquid microphone, where a needle was placed just barely in contact with a liquid conductor, and as the diaphram vibrated, the needle dipped more-or-less into the liquid, resulting in more-or-less current passing to the receiver. Bell used a Gray liquid transmitter for many of his early public demonstrations. The liquid transmitter had the problem that the waves formed on the surface of the liquid resulted in interference. | Gray's harmonic telegraph apparatus follows in the track of Reis and Bourseul — that is to say, the interruption of the current by a vibrating contact. Gray recognized the lack of fidelity of the make-break transmitter, and reasoned by analogy with the lovers telegraph that if the current could be made to model more closely the movements of the diaphram rather than simply turning the circuit on and off, a greater fidelity might be achieved. Gray built and patented a liquid microphone, where a needle was placed just barely in contact with a liquid conductor, and as the diaphram vibrated, the needle dipped more-or-less into the liquid, resulting in more-or-less current passing to the receiver. Bell used a Gray liquid transmitter for many of his early public demonstrations. The liquid transmitter had the problem that the waves formed on the surface of the liquid resulted in interference. | ||
| ===Carbon Grain transmitter=== | |||
| ===Thomas Edison=== | ===Thomas Edison=== | ||
| ] took the next step in developing telephonic fidelity with his invention of the carbon grain transmitter. Edison discovered that carbon grains, squeezed between two metal plates had a resistance that was related to the pressure |
] took the next step in developing telephonic fidelity with his invention of the ]. Edison discovered that carbon grains, squeezed between two metal plates had a resistance that was related to the pressure; thus, the grains could vary their resistance as the plates moved in response to sound waves, and reproduce sound with good fidelity, without the problems associated with a liquid contact. This style of transmitter remained standard in telephony until the 1980s, and is still produced. | ||
| ===Alexander Graham Bell=== | ===Alexander Graham Bell=== | ||
Revision as of 03:10, 18 January 2006
The history of the invention of the telephone is a confusing morass of claims and counterclaims, further worsened by the huge mass of lawsuits which hoped to resolve the patent claims of individuals. It is important to note that there is no one "inventor of the telephone", though Alexander Graham Bell is often credited as such. The modern telephone is the result of work done by many people, all worthy of recognition of their contributions to the field. Bell was merely the first to patent the telephone.
Non-electric 'telephones'
There is a sense in which a telephone is any mechanism capable of conducting sound for a great distance. The very earliest telephones were mechanical devices based on sound transportation through air or other physical media rather than electrical devices depending on electro-magnetic signals.
According to a letter in the Peking Gazette, in 968, the Chinese inventor Kung-Foo-Whing invented the thumtsein, which probably transported the speech through pipes. Speaking tubes remained common and can still be found today.
The lover's telephone (or string telephone) has also been known for centuries, connecting two diaphragms with string or wire which transmits the sound from one to the other by vibrations along the string and not through electric current. The classic example is the children's toy made by connecting the bottoms of two paper cups with string.
Electro-magnetic transmitters (telephone)
Antonio Meucci
It may be argued that the telephone was invented around 1860 by Antonio Meucci who called it teletrophone.
From Despite a public statement by the then Secretary of State that "there exists sufficient proof to give priority to Meucci in the invention of the telephone," and despite the fact that the United States initiated prosecution for fraud against Bell's patent, the trial was postponed from year to year until, at the death of Meucci in 1896, the case was dropped.
The first American demonstration of Meucci's invention took place in 1860, and had a description of it published in New York's Italian language newspaper. Meucci invented a paired electro-magnetic transmitter and receiver, where the motion of a diaphram modulated a signal in a coil by moving an electromagnet. This resulted in a good fidelity, but a very weak signal. Meucci is also credited with the early invention of the anti-sidetone circuit, and of inductive loading of telephone wires to increase long-distance signals. Unfortunately, serious burns, lack of English and poor business abilities resulted in Meucci failing to develop his inventions commercially in America. Meucci demonstrated some sort of instrument in 1849 in Havana, Cuba, but the evidence is unclear if this was an electric telephone or a variant on the string telephone using wires.
Meucci was recognised as the first inventor of the telephone by the United States Congress, in its resolution 269 dated 11 June 2002.
Charles Bourseul
In 1854 in the magazine "L'Illustration de Paris" M. Charles Bourseul, a French telegraphist, published a plan for conveying sounds and even speech by electricity. Suppose,' he explained, 'that a man speaks near a movable disc sufficiently flexible to lose none of the vibrations of the voice; that this disc alternately makes and breaks the currents from a battery: you may have at a distance another disc which will simultaneously execute the same vibrations.... It is certain that, in a more or less distant future, speech will be transmitted by electricity. I have made experiments in this direction; they are delicate and demand time and patience, but the approximations obtained promise a favourable result.'
Johann Philipp Reis
In 1860 Johann Philipp Reis produced a device which could transmit musical notes, and even a lisping sentence or two. The first sentence spoken on it was "Das Pferd frisst keinen Gurkensalat" (the horse eats no cucumber salad). The motives for stating such a sentence is currently in dispute. See Reis' telephone for a detailed description. The Reis transmitter was a make-break transmitter. That is, a needle attached to a diaphram was alternately pressed against, and released from a contact as the sound moved the diaphram. This make-or-break signaling was able to transmit tones, and some vowels, but since it did not follow the analog shape of the sound wave (the contact was pure digital, on or off) it could not transmit consonants, or complex sounds. The Reis transmitter was very difficult to operate, since the relative position of the needle and the contact were critical to the device's operation at all. This can be called a "telephone", since it did transmit sounds over distance, but is hardly a telephone in the modern sense, as it failed to transmit a good copy of any supplied sound. Reis' invention is best known then as the "musical telephone".
Cromwell Varley
Around 1870 Mr. Cromwell Fleetwood Varley, F.R.S., a well-known English electrician, patented a number of variations on the audio telegraph based on Reis' work. He never claimed or produced a device capable of transmitting speech, only pure sounds.
Poul la Cour
Around 1874 Poul la Cour, a Danish inventor, experimented with audio telegraphs on a line of telegraph between Copenhagen and Fredericia in Jutland. In this a vibrating tuning-fork interrupted the current, which, after traversing the line, passed through an electromagnet, and attracted the limbs of another fork, making it strike a note like the transmitting fork. Moreover, the hums were made to record themselves on paper by turning the electromagnetic receiver into a relay, which actuated a Morse code printer by means of a local battery. Again, la Cour made no claims of transmitting voice, only pure tones.
Elisha Gray
Mr. Elisha Gray, of Chicago also devised a tone telegraph of this kind about the same time as Herr La Cour. In this apparatus a vibrating steel reed interrupted the current, which at the other end of the line passed through an electromagnet and vibrated a matching steel reed near its poles. Gray's 'harmonic telegraph,' with the vibrating reeds, was used by the Western Union Telegraph Company. Since more than one set of vibrations — that is to say, more than one note — can be sent over the same wire simultaneously, the harmonic telegraph can be utilised as a 'multiplex' or many-ply telegraph, conveying several messages through the same wire at once; and these can either be read by the operator by the sound, or a permanent record can be made by the marks drawn on a ribbon of travelling paper by a Morse recorder.
Gray's harmonic telegraph apparatus follows in the track of Reis and Bourseul — that is to say, the interruption of the current by a vibrating contact. Gray recognized the lack of fidelity of the make-break transmitter, and reasoned by analogy with the lovers telegraph that if the current could be made to model more closely the movements of the diaphram rather than simply turning the circuit on and off, a greater fidelity might be achieved. Gray built and patented a liquid microphone, where a needle was placed just barely in contact with a liquid conductor, and as the diaphram vibrated, the needle dipped more-or-less into the liquid, resulting in more-or-less current passing to the receiver. Bell used a Gray liquid transmitter for many of his early public demonstrations. The liquid transmitter had the problem that the waves formed on the surface of the liquid resulted in interference.
Thomas Edison
Thomas Alva Edison took the next step in developing telephonic fidelity with his invention of the carbon grain transmitter. Edison discovered that carbon grains, squeezed between two metal plates had a resistance that was related to the pressure; thus, the grains could vary their resistance as the plates moved in response to sound waves, and reproduce sound with good fidelity, without the problems associated with a liquid contact. This style of transmitter remained standard in telephony until the 1980s, and is still produced.
Alexander Graham Bell
Alexander Graham Bell is commonly credited as the first inventor of the telephone. The classic story of his crying out "Watson, come here! I need you!" is a part of the common western mythos.
Controversy
Until recently, Bell was not recognized as the "inventor" of the telephone, althought thanks to the money of the great lobby Western Union, still existing, he has helped to organize a world business. He knew Meucci and he took the merit -besides the project- that in reality belonged to a poor Italian. In the United States, there are a few reflections for inventing the device, but the truth is well known ever since the past. In fact in 2002 the United States House of Representatives passed a symbolic bill conferring official recognition for the invention of the telephone to Meucci. Consequently, in the USA, Bell is today widely recognized as a thief.