HISTORY OF THE WIRE COMMUNICATIONS: BEGINNINGS OF THE TELEGRAPH AND THE TELEPHONE.

The Morse code | The telegraph: basic electrical circuits | The submarine telegraph | Speaking through a wire | The telephone, an accidental discovery | The wonderful progress of the Bell Company and the great fortune of its shareholders | History of the telephone central | How the lines of great length perfected |The first transmission of images by cable |The wireless telegraph

The Old Times - Los viejos Tiempos | Español : Historia de la comunicación por teléfonos , inicios del telégrafo y el teléfono .

From immemorial times, the man has used some kind of signals method through the space to put himself in contact with his fellow men , trying to overcome the distances, and to satisfy therefore one of his greatest human needs as it is the communication. Several of the methods are explained in present Literature with plenty of details, while others, are only accidentally mentioned in some old literary work. It is known that Cyro the Great , King of Persia, used a mysterious system of signals, by which he could send a message through the Persian Empire in a day, a distance that a man by horse would not be able to cross in less than thirty days. The Roman soldiers would send signals moving their shields, in certain positions or by means of sparkles produced by these shields with the light of the Sun.

The American Indians used to make a bonfire which was covered periodically with a blanket to produce smoke signals , which then were translated in words by a distant observer.

Tha Sacred History contains many references to smoke signals , and it is supposed that this class of signals were sent from the Babel tower . Napoleón, in his campaign to Russia, communicated with Paris, in cleared days, by a continue system of semaphoric stations. The semaphoric system of communication called telegraph was developed, in effect, in a considerable way in France and in smaller degree in England and Germany.

None of these methods could be used at night, nor even in a day of little conditions of visibility. When Arthur Wellesley, Duke of Wellington was fighting in Spain there was a great panic in London a day when a semaphoric message was sent from Portsmouth to the admiralty, saying: " Wellington, defeated. " later on , these words , " to the French ", were received, which had to be delayed by a sudden fog in Portsmouth.

The communication at night by sparkles of lights has been used during many centuries. It seems that China was the first in using the rockets as signals throughout the Great Wall to warn of an imminent attack. The same artifice was used during many years as a signal of shipwreck by the shps in the sea. In some time, the British Navy would send signals at night raising and lowering a lantern in a bucket.

In many cases, when the vision became difficult, the signals were sent by means of sounds of bells or whistles and even guns. The distance at which the signals could be sent by some of these means was directly limited by the sensitivity of the eye or the ear and by the nature of the intermediate obstacles. Only the heliograph, or the mirror used for reflecting the rays of the Sun, could be used for sending signals at distances of several kilometers. In all the other cases, the signals had to repeat themselves from station to station, arduously and under favorable conditions to avoid the transmission errors.

The fact that the electricity could be sent through a wire of considerable length was demonstrated firstly by Stephen Gray (1666-1736) in 1729; but apparently he did not think that his discovery provided the means for the fast transmission of signals. The first indication about the use of the electricity in the communication appears in an anonymous letter to the Scot's Magazine in 1753. It is thought that that letter has been written by Charles Morrison, a Scottish surgeon.

Preparing the way for the advent of the electrical telegraph

The method that proposed Morrison, like many others that followed to him, demanded the use of as many wires as letters had to be transmitted. Charging the wires successively with an electrostatic machine (in that time there were no batteries nor dynamos), and causing that the respective charges attract pieces of paper at the other end of the line; dispatches could be sent at one or two miles of distance with considerable speed.

The development of the electrical telegraph as it was known during first years of the XX century , from this primitive device, demanded many years of discoveries and inventions. First ,it was made necessary to provide a better isolation for the conductors. The crystal insulator use on wood posts, as it was used later, was not adopted until 1828. More important yet it was the invention of the electrical battery, that could send a constant current through the wires. Although the first battery was constructed by Volta in 1800, a battery of sufficient energy for the needs of the telegraph was not invented until 1836. In the first part of the XIX century, several inventors devised electrical telegraphs that demanded no more than two conductors, constituting this one a remarkable improvement on the previous systems.

The discovery by accident of the electromagnetism by the Danish Hans Christian Oersted , in 1820, can be considered as the culminating episode in the development of the electrical telegraph. Given the fact that before this discovery different impulses of electrical current could be sent trough a wire of considerable length , but it had not been found a satisfactory means to recognize this impulse in the receiving end of the line. Many coarse methods had been used with this objective . De Salvá, a Spanish man , suggested, for example, that a man placed in the receiving end of the line hold the ends of wires with both hands and interpreted the dispatch by means of the number of electrical shocks that he received.

Oersted discovered that a magnetic needle located near a wire could be turned aside when a current through that wire was sent. Andre Marie Ampére suggested immediately that the deviation of a magnetic needle could be used for the reception of electrical signals; but a practical system of needle telegraph was not devised until 1837, by Wheatstone and Cook, in England. Joseph Henry , professor in the school of Princeton, contributed greatly to the knowledge of electromagnetism, between 1828 and 1831. He demonstrated that the magnetic effect of an electrical current could often be amplified coiling a wire around a sweet iron bar and he explained to his students the possibility of tolling the Bells of a remote church with his electromagnet. It is really peculiar that the professor Henry, with his outstanding knowledge of the electricity and magnetism, did not appreciate the industrial importance of his electromagnet.

The electrical telegraph , the result of a fortuitous conversation

It seems that the invention of the practical telegraph, by Samuel Finley Breese Morse , a professional artist of North America in 1837, was consequence of a very fortuitous conversation between Morse and the doctor Charles T. Jackson, of Boston, during a trip from Le Havre to New York in 1832. Later, when Morse was demanded to defend his patents before the Supreme Court, in 1850, the Dr Jackson argued that he had suggested most of the factors that led to the invention by Mr. Morse during that marine trip. The professor Henry also established that the principles of Morse's invention were of vulgar knowledge before the registry of the patent. The captain and passengers of the ship opposed the declaration of doctor Jackson, nevertheless, and the Court maintained the validity of Morse's patent .

Whether Morse has made use or not of the suggestions of others does not matter now, the case is that he triumphed by force of patience and perseverance , constructing an electrical telegraph that was superior to any one of the others. His first line was constructed with a budget voted by the Congress, between Baltimore and Washington, in 1844. The Morse's telegraph principle soon spreaded to everywhere.

When the commutator in the emitting station is closed, the battery sends a current to an electromagnet placed in the receiving station , being this current transported by a simple isolated wire and returning by the Earth. When the current passes trough the coils of the electromagnet, an iron sheet , maintained separated of the poles of the electromagnet by a light spring , is attracted producing an acute sound . In the first Morse's telegraph , at the end of the vibrant iron sheet there was a pen. The attraction of the iron sheet forced the pen to contact with a movable strip of paper, marking on it a series of short straight lines that represented with their length the relative duration of time that the circuit had been closed, transmitting therefore the message in dots and dashes .

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