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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Electric telegraph. History of invention and production
Directory / The history of technology, technology, objects around us Telegraph - a means of transmitting a signal by wire, radio or other telecommunication channels.
Until the middle of the XNUMXth century, the only means of communication between the European continent and England, between America and Europe, between Europe and the colonies, was steamship mail. People learned about incidents and events in other countries with a delay of whole weeks, and sometimes even months. For example, news from Europe to America was delivered in two weeks, and this was not the longest time yet. Therefore, the creation of the telegraph met the most urgent needs of mankind. After this technical innovation appeared in all parts of the world and telegraph lines circled the globe, it took only hours, and sometimes even minutes, for news on electrical wires from one hemisphere to rush to the other. Political and stock reports, personal and business messages on the same day could be delivered to interested parties. Thus, the telegraph should be attributed to one of the most important inventions in the history of civilization, because with it the human mind won the greatest victory over distance. But besides the fact that the telegraph opened a new milestone in the history of communications, this invention is also important because here for the first time, and, moreover, on a fairly significant scale, electrical energy was used. It was the creators of the telegraph who first proved that electric current can be made to work for human needs and, in particular, for the transmission of messages. Studying the history of the telegraph, one can see how for several decades the young science of electric current and telegraphy went hand in hand, so that every new discovery in electricity was immediately used by inventors for various methods of communication. As you know, people got acquainted with electrical phenomena in ancient times. Even Thales, rubbing a piece of amber with wool, then watched how the Goth attracted small bodies to itself. The reason for this phenomenon was that, when rubbed, an electric charge was imparted to amber. In the XNUMXth century, people learned how to charge bodies with an electrostatic machine. It was soon established that there are two types of electric charges: they began to be called negative and positive, and it was noticed that bodies with the same charge sign repel each other, and different signs attract. For a long time, while studying the properties of electric charges and charged bodies, they had no idea about electric current. It was discovered, one might say, by accident by the Bolognese professor Galvani in 1786. For many years, Galvani experimented with an electrostatic machine, studying its effect on the muscles of animals - primarily frogs (Galvani cut out a frog's leg along with part of the spinal column, one electrode from the machine led to the spine, and the other to some muscle, when passing discharge, the muscle contracted and the foot twitched). Once Galvani hung a frog's leg with a copper hook from an iron lattice of a balcony and, to his great amazement, noticed that the leg twitched as if an electric discharge had been passed through it. This contraction occurred each time the hook was connected to the grate. Galvani decided that in this experiment the source of electricity was the frog's leg itself. Not everyone agreed with this explanation. The Pisan professor Volta was the first to guess that electricity arises from the combination of two different metals in the presence of water, but not pure, but representing a solution of some salt, acid or alkali (such an electrically conductive medium was called an electrolyte). So, for example, if plates of copper and zinc are soldered together and immersed in an electrolyte, electrical phenomena will occur in the circuit, which are the result of a chemical reaction taking place in the electrolyte. The following circumstance was very important here - if before scientists were able to receive only instantaneous electric discharges, now they were dealing with a fundamentally new phenomenon - direct electric current. The current, unlike the discharge, could be observed for long periods of time (until the chemical reaction took place in the electrolyte to the end), it could be experimented with, and finally it could be used. True, the current that arose between a pair of plates turned out to be weak, but Volta learned to amplify it. In 1800, by connecting several such pairs together, he received the first electric battery in history, called a voltaic column. This battery consisted of copper and zinc plates laid one on top of the other, between which there were pieces of felt moistened with a salt solution. When investigating the electrical state of such a column, Volta found that on medium pairs, the electrical voltage is almost completely imperceptible, but it increases on more distant plates. Consequently, the voltage in the battery was the greater, the greater the number of pairs. Until the poles of this column were connected to each other, no action was found in it, but when the ends were closed with a metal wire, a chemical reaction began in the battery, and an electric current appeared in the wire. The creation of the first electric battery was an event of the greatest importance. Since that time, electric current has become the subject of the closest study by many scientists. After that, inventors appeared who tried to use the newly discovered phenomenon for human needs. It is known that electric current is an ordered movement of charged particles. For example, in a metal it is the movement of electrons, in electrolytes it is the movement of positive and negative ions, etc. The passage of current through a conducting medium is accompanied by a number of phenomena, which are called the actions of the current. The most important of them are thermal, chemical and magnetic. Speaking about the use of electricity, we usually mean that one or another of the effects of current finds application (for example, in an incandescent lamp - thermal, in an electric motor - magnetic, in electrolysis - chemical). Since initially the electric current was discovered as a result of a chemical reaction, the chemical effect of the current attracted attention first of all. It was noticed that when current passes through electrolytes, the release of substances contained in the solution, or gas bubbles, is observed. When passing current through water, it was possible, for example, to decompose it into its constituent parts - hydrogen and oxygen (this reaction is called water electrolysis). It was this action of the current that formed the basis of the first electric telegraphs, which are therefore called electrochemical. In 1809, the first draft of such a telegraph was presented to the Bavarian Academy. Its inventor, Semering, proposed using gas bubbles for communication equipment that were released when current passed through acidified water. The Semering telegraph consisted of: 1) voltaic column A; 2) the alphabet B, in which the letters corresponded to 24 separate wires connected to the voltaic column by means of a wire stuck into the holes of the pins (on B2 this connection is shown in an enlarged view, and on B3 a top view is given); 3) rope E from 24 wires twisted together; 4) alphabet C1, which perfectly corresponds to set B and is placed at the station receiving dispatches (here, individual wires passed through the bottom of a glass vessel with water (C3 represents the plan of this vessel); 5) alarm clock D, consisting of a lever with a spoon (it is enlarged presented in C2).
When Semering wanted to telegraph, he first signaled another station with the help of an alarm clock and for this he stuck two poles of the conductor into the loops of the letters B and C. The current passed through the conductor and the water in the glass vessel C1, decomposing it. Bubbles accumulated under the pit of the stomach and raised it so that it took the position indicated by the dotted line. In this position, a movable lead ball, under the influence of its own gravity, rolled into a funnel and descended along it into a cup, causing an alarm. After everything was prepared at the receiving station for receiving the dispatch, the sender connected the poles of the wire in such a way that the electric current passed sequentially through all the letters that make up the message being transmitted, and the bubbles were separated at the corresponding letters of the other station. Subsequently, this telegraph greatly simplified Schweiger, reducing the number of wires to just two. Schweiger introduced various combinations in the transmission of current. For example, a different duration of the current and, consequently, a different duration of water decomposition. But this telegraph was still too complicated: watching the release of gas bubbles was very tiring. The work went slowly. Therefore, the electrochemical telegraph never received practical application. The next stage in the development of telegraphy is associated with the discovery of the magnetic action of the current. In 1820, the Danish physicist Oersted, during one of his lectures, accidentally discovered that a conductor with electric current affects a magnetic needle, that is, it behaves like a magnet. Interested in this, Oersted soon discovered that a magnet with a certain force interacts with a conductor through which an electric current passes - attracts or repels it. In the same year, the French scientist Argo made another important discovery. The wire through which he passed an electric current accidentally turned out to be immersed in a box of iron filings. The sawdust stuck to the wire as if it were a magnet. When the current was turned off, the sawdust fell off. Having studied this phenomenon, Argo created the first electromagnet - one of the most important electrical devices that is used in many electrical devices. The simplest electromagnet will easily prepare everyone. To do this, you need to take a bar of iron (preferably unhardened "soft" iron) and tightly wind insulated copper wire around it (this wire is called the winding of an electromagnet). If we now attach the ends of the winding to the battery, the bar will be magnetized and will behave like a well-known permanent magnet, that is, it will attract small iron objects. With the disappearance of the current in the winding when the circuit is opened, the bar will instantly demagnetize. Usually an electromagnet is a coil inside which is inserted an iron core. Observing the interaction of electricity and magnetism, Schweiger invented the galvanoscope in the same 1820. This device consisted of a single coil of wire, inside of which a magnetic needle was placed in a horizontal state. When an electric current was passed through the conductor, the arrow deviated to the side. In 1833, Nervandar invented the galvanometer, in which the current was measured directly from the angle of deflection of a magnetic needle. By passing a current of known strength, it was possible to obtain a known deviation of the galvanometer needle. The system of electromagnetic telegraphs was built on this effect. The first such telegraph was invented by a Russian subject, Baron Schilling. In 1835, he demonstrated his pointer telegraph at a congress of natural scientists in Bonn. Schilling's transmission device consisted of a keyboard with 16 keys that served to close the current. The receiving device consisted of 6 galvanometers with magnetic needles suspended on silk threads from copper racks; above the arrows, two-color paper flags were fastened on threads, one side of them was painted white, the other black. Both Schilling telegraph stations were connected by eight wires; of these, six were connected to galvanometers, one served for the reverse current and one for the drafting apparatus (electric bell). When a key was pressed at the sending station and the current was turned on, the corresponding arrow was deflected at the receiving station. Different positions of black and white flags on different disks gave conditional combinations corresponding to letters of the alphabet or numbers. Later, Schilling improved his apparatus, and 36 different deviations of his single magnetic needle corresponded to 36 conditional signals.
The demonstration of Schilling's experiments was attended by the Englishman William Cook. In 1837, he somewhat improved the Schilling apparatus (Cook's arrow, with each deviation, pointed to one or another letter depicted on the board, words and whole phrases were formed from these letters) and tried to arrange a telegraph message in England. In general, telegraphs, which worked on the principle of a galvanometer, received some distribution, but very limited. Their main disadvantage was the complexity of operation (the telegraph operator had to quickly and accurately catch the vibrations of the arrows by eye, which was quite tiring), as well as the fact that they did not record the transmitted messages on paper. Therefore, the main path of the development of telegraph communication went a different way. However, the construction of the first telegraph lines made it possible to solve some important problems concerning the transmission of electrical signals over long distances. Since the wire made it very difficult to spread the telegraph, the German inventor Steingel tried to limit himself to only one wire and conduct the current back along the railroad tracks. To this end, he conducted experiments between Nuremberg and Fürth and found out that there was no need for a return wire at all, since it was enough to ground the other end of the wire to transmit a message. After that, they began to ground the positive pole of the battery at one station, and the negative pole at the other, thus eliminating the need to conduct a second wire, as was done before. In 1838, Steingel built a telegraph line in Munich about 5 km long, using the earth as a conductor for the return current. But in order for the telegraph to become a reliable communication device, it was necessary to create an apparatus that could record the transmitted information. The first such apparatus with a self-recording device was invented in 1837 by the American Morse.
Morse was an artist by profession. In 1832, during a long voyage from Europe to America, he got acquainted with the device of an electromagnet. Then he had the idea to use it for signaling. By the end of the journey, he had already managed to come up with an apparatus with all the necessary accessories - an electromagnet, a moving strip of paper, as well as his famous alphabet, consisting of a system of dots and dashes. But it took many more years of hard work before Morse managed to create a workable model of the telegraph apparatus. The matter was complicated by the fact that at that time in America it was very difficult to get any electrical appliances. Literally, Morse had to do everything himself or with the help of his friends from New York University (where he was invited in 1835 as a professor of literature and fine arts). Morse took a piece of soft iron from the forge and bent it into a horseshoe shape. Insulated copper wire was not yet known Morse bought several meters of wire and insulated it with paper. The first great disappointment befell him when insufficient magnetization of the electromagnet was discovered. This was due to the small number of turns of the wire around the core. Only after reading Professor Henry's book, Morse was able to correct his mistakes and assembled the first working model of his apparatus. On a wooden frame attached to the table, he installed an electromagnet and a clockwork that set the paper tape in motion. He attached the anchor (spring) of a magnet and a pencil to the pendulum of the clock. Produced with the help of a special device, a telegraph key, closing and opening the current made the pendulum swing back and forth, and the pencil drew dashes on the moving paper tape that corresponded to the conventional signs given by the current. This was a great success, but new difficulties arose. When transmitting a signal over a long distance, due to the resistance of the wire, the signal strength weakened so much that he could no longer control the magnet. To overcome this difficulty, Morse invented a special electromagnetic contactor, the so-called relay. The relay was an extremely sensitive electromagnet that responded to even the weakest currents coming from the line. With each attraction of the armature, the relay closed the current of the local battery, passing it through the electromagnet of the writing instrument.
Thus Morse invented all the major parts of his telegraph. He finished the work in 1837. It took him another six years to futile attempts to interest the US government in his invention. Only in 1843, the US Congress decided to allocate 30 thousand dollars for the construction of the first telegraph line 64 km long between Washington and Baltimore. At first it was laid underground, but then it turned out that the insulation could not withstand dampness. I had to urgently correct the situation and pull the wire above the ground. On May 24, 1844, the first telegram was solemnly sent. Within four years telegraph lines were in place in most states. The Morse telegraph apparatus proved to be extremely practical and easy to use. Soon he received the widest distribution throughout the world and brought his creator well-deserved fame and fortune. Its design is very simple. The main parts of the apparatus were the transmitting device - the key, and the receiving device - the writing instrument.
The Morse key consisted of a metal lever that rotated around a horizontal axis. Both on the front and on the rear axle there were small metal cones, each of which touched the plates lying under it, as a result of which the current was closed. To imagine how the key works, let's denote all its contacts with numbers. Let the front cone be 1 and the back cone 3. The plates lying under them will be considered the 2nd and 4th contacts, respectively. In the key position, when the handle is not lowered, contacts 3 and 4 are closed, and 1 and 2 are open. Plate 2 is connected to the battery conductor. A wire wire is connected to the body of the lever to a remote station, while the plate 4 is connected to the writing instrument. At the receiving station, the receiving wire goes to the receiving magnet.
When a telegram arrived, the electric current passed through the levers of the key in such a way that it came from the wire to plate 4 and then to the writing instrument (contacts 1 and 2 were disconnected at that time). When telegrams were sent, contacts 3 and 4 were disconnected. Then the current from the battery, when contacts 1 and 2 were closed, went to the receiving station. If the telegraph operator closed the circuit for a short time, a short signal passed; if he held the key down longer, the signal was longer.
The writing instrument at the receiving station converted these signals into a system of dots and dashes. He worked as follows. From the transmitting station, the current flowed to the coils M and M1. The pieces of iron in them were magnetized and attracted the iron plate B. As a result, the pin O, located on the other arm A, was pressed against the paper strip P, which was rolled up from the circle R by means of rollers V and W in the direction indicated by the arrow. At the same time, the end of the pin, on which there was a pencil, wrote dots or dashes on the tape, depending on whether it was pressed for a short or longer time. As soon as the current stopped (this happened every time the telegraph operator at the transmitting station opened the circuit with a key), the spring f pulled the pin down, as a result of which the plate B moved away from the electromagnet. The movement of the rollers V and W came from a clock mechanism, which was driven by lowering the weight G. The degree of deflection of the lever could be adjusted using the screws m and n. The inconvenience of the Morse apparatus was that the messages transmitted by it were understandable only to professionals familiar with Morse code. In the future, many inventors worked on the creation of direct-printing devices that record not conditional combinations, but the words of the telegram themselves. Yuz's letter-printing apparatus, invented in 1855, became widespread. Its main parts were: 1) a keyboard with a rotating contactor and a board with a hole (this is an accessory of the transmitter); 2) a letter wheel with a typing device (this is a receiver). The keyboard had 28 keys, with which it was possible to transmit 52 characters.
Each key was connected by a system of levers to a copper rod. In the usual position, all these rods were in nests, and all the nests were located on the board in a circle. Above these sockets, a contactor, the so-called trolley, rotated at a speed of 2 revolutions per second. It was driven by a 60 kg descending weight and a system of gear wheels. At the receiving station, the letter wheel rotated at exactly the same speed. On its rim were teeth with signs. The rotation of the trolley and the wheel occurred synchronously, that is, at the moment when the trolley passed over the nest corresponding to a certain letter or sign, the same sign turned out to be in the lowest part of the wheel above the paper tape. When a key was pressed, one of the copper rods rose and protruded from its socket. When the cart touched it, the circuit was completed. The electric current instantly reached the receiving station and, passing through the windings of the electromagnet, caused the paper tape (which moved at a constant speed) to rise and touch the bottom tooth of the printing wheel. Thus, the desired letter was printed on the tape. Despite the apparent complexity, Yuz's telegraph worked quite quickly and an experienced telegraphist transmitted up to 40 words per minute on it. Originating in the 40s of the XIX century, telegraph communications developed rapidly in the following decades. Telegraph wires crossed continents and oceans. In 1850 England and France were connected by a submarine cable. The success of the first submarine line caused a number of others: between England and Ireland, England and Holland, Italy and Sardinia, etc. In 1858, after a series of unsuccessful attempts, a transatlantic cable was laid between Europe and America. However, he worked only three weeks, after which the connection was cut off. Only in 1866 a permanent telegraph connection was finally established between the Old and New Worlds. Now the events taking place in America became known in Europe on the same day, and vice versa. In subsequent years, the rapid construction of telegraph lines continued throughout the globe. Their total length in Europe alone was 700 thousand km. Author: Ryzhov K.V.
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