TELEGRAPH (Gr. tele, far off, and grapho, to write) is a general name for any means of conveying intelligence other than by voice or writing. The idea of speed is also implied. It is now used to mean exclusively the transmission of messages over a wire by means of electricity. Alarm-fires (see BEACON), the semaphore (q.v.), and the signals (q.v.) used at sea are among the earlier forms of telegraph. But all other agents are now entirely surpassed by the electric telegraph. The practical application of the scientific laws under which the telegraph operatesin the form of the instrument still, with certain modifications, in general use-is supposed to have been first made by S. F. B. Morse (q.v.) in 1832-35. With the discovery that electric currents could be transmitted instantly over long distances came the idea of employing them for signalling, and in 1774 Bishop Watson made some experiments in discharging leyden jars through 10,600 feet of wire suspended on wooden poles in the neighborhood of London. In the Scotts Magazine in 1753 à detailed description of a plan for electric telegraphy is given, and in 1774 a telegraph line was erected at Geneva, Switzerland, which consisted of twenty-four wires connected to pith-ball electroscopes each representing a letter. The difficulty of using frictional machines, however, prevented the attainment of any practical results in this direction before the discovery of the voltaic cell. In Germany the invention of the telegraph is credited to Sömmering of Munich, whose original apparatus, built about 1811, was exhibited in operation at the Congress of Electricians at Frankfort, Germany, in 1891. Baron Schilling in 1832 exhibited a telegraphic model in Russia in which the letters were represented by the deflections of a single needle. Weber and Gauss modified this plan by using a magnet suspended horizontally, to which a mirror was attached. Steinheil of Munich was the first to notice the important fact that by using the earth as a conductor no return wire is needed. He also invented a code using but two elementary signals in different com- binations, and an instrument for recording the characters on a moving strip of paper in the shape of two rows of dots. The telegraph was established as a commercial enterprise in Germany with Steinheil's system, in America with Morse's, and in England with Wheatstone and Cooke's. The first telegraph line in commercial operation was between Paddington and Drayton, in England, in 1835, and was 13 m. in length. This antedated by seven years the Morse line, which was laid between Washington and Baltimore. The printing telegraph was first invented by Alfred Vail, of New Jersey, in 1837, but it was not until 1841 that Wheatstone made his first model of the instrument. In 1845 Mr. C. J. Fleischmann exhibited the Morse apparatus to the emperor of Austria, at Vienna, and with such success that it was adopted by the Austrian government. In 1848 two Americans built a line between Hamburg and Cuxhaven at the mouth of the Elbe, a distance of 90 m., which was operated on the American plan with Morse instruments, and was employed for reporting marine news. The Wheatstone apparatus did not work well except through comparatively short distances, and at a very low rate of speed, and was altogether inferior to the Morse telegraph. The superior efficiency of the latter in working direct through long distances was caused by the application of the relay and local circuit. In Oct., 1851, a convention of deputies from Austria, Prussia, Bavaria, Würtemburg, and Saxony met at Vienna to effect a common and uniform telegraph system. By this convention it was decided that the Morse system was practically the best, and this was therefore adopted. In the beginning of Morse's experiments he made use of the fountain pen and other devices for recording the characters; but in the end, the stylus or steel point for embossing these was found to be the most convenient and satisfactory. The space at our command will not permit us to describe the various steps which led to the introduction of the perfected telegraph. We must be content to furnish a description of the apparatus and methods now in use, and to give some statistics showing the growth of the business and its present extent. In our description of instruments, etc., we shall assume the reader to be familiar with the chief features of electricity (see GALVANISM) and of electro-magnetism (see MAGNETISM). The apparatus first developed' by Prof. Morse depended upon the principle brought out by Prof. Henry, that a piece of iron when wound with wire will exert magnetic attraction as long as a current of electricity sent along the wire is passed through the coil. The temporary magnetic attraction so produced was used by Prof. Morse to impart a slight movement to a lever placed near the magnet, thereby giving a visible indication each time that the current was sent through the wire at the distant station. Different combinations of charges of current, each one being of only momentary duration, were arranged to represent the letters of the alphabet, and by this means messages were spelled out by short impulses or dots of current over the wire from Washington to Baltimore. This is the foundation of all electric telegraphs. The application of the principle is modified in innumerable ways, for the purposes of permitting the transmission and the reception of the messages to be done in various ways that are convenient for special places and uses. The numerous instruments so employed may be classed under two heads-namely, those which record the signals so that they may be read at any time after the message is received, and those which give only a passing signal, indicated by a sound or a motion, and which therefore require the constant attention of a receiving operator. Among the former are several kinds-namely, those giving a record in arbitrary signs -i.e., in the dots and dashes of the Morse alphabet; those which print the message in ordinary type, such as the modern type-printing instrument, of which the Phelps printer ་ is the most common, and lastly a class of instruments giving a fac-simile of the message. The last class is not much used, and the instruments which print in type, though used extensively, are confined to main offices where a great many messages are sent rapidly over long lines. We have not space to describe these instruments. See Prescott's Electricity and the Electric Telegraph. The greater part of the telegraphing of the world is done by the Morse non-recording instruments, that is the Morse sounder and key, as they are called, and to these we shall therefore devote the greater part of our descrip. tion, referring the reader to the illustration plate TELEGRAPH INSTRUMENTS. The Morse Telegraph and Morse Instruments.-The leading principle in the Morse instruments is that by the depression of a key, or by other means, at the sending station an electric circuit is "closed" or completed, and a signal is transmitted along the wire to a distant receiving station, where on its arrival it reproduces the signal by the action of an electro-magnet, or otherwise. Electrically, the Morse system consists of a battery or other source of electricity and a wire, with the instruments connecting the telegraph stations and returning to the battery. This is done so that a current of electricity is kept in continuous circulation in the wire except when interrupted. A signalling outfit at each office is connected to the wire, and consists of a key for interrupting the current, and thereby producing signals throughout the entire length of the wire, and a receiving instrument or sounder, consisting of an electro-magnet with a responsive lever, which is attracted by the magnet making an audible click when the current passes. The sounder, fig. 4, consists of a small magnet wound with insulated wire and firmly attached to a base. In front of the poles of the magnet a bar of soft iron, suitable to be attracted by it, is supported by a lever, pivoted at one extremity in such a way that the lever is free to descend and allow the keeper to approach the magnet when attracted by it. The weight of the lever and of the keeper are counterbalanced by a spring which is made adjustable, and is always so adjusted that the keeper is kept away from the magnet by a slight pressure. The motion of the lever, upward and downward, or toward and from the magnet, is limited by adjustable stops. When the keeper and lever are attracted downward by the magnet an audible click is produced by their striking the downward stop. When the keeper is released by the magnet and carried back by the pressure of the spring another click is produced by its striking the upward stop. These clicks are always different in sound, so that the skilled operator has no difficulty in distinguishing an upward from a downward stroke of the lever. The length of wire wound upon the magnet is always proportionate to the length of the line, in order to get the best effect. The Transmitting Key.-The "key" by which signals are transmitted from the operator at the sending office is shown in fig. 3 in its most improved form. It consists of a lever pivoted near the middle and carrying at one end a knob by which it is manipulated upward and downward by the operator in sending signals, or "writing," as it is sometimes called. Two platinum contacts are fastened respectively to the under side of the lever and to an insulated piece on the upper side of the base. These contacts are exactly opposite to each other, so that they come together every time the key is depressed. The lever is held up and the contacts therefore kept apart, when the key is not depressed by the operator, by a small spiral spring which presses upward under the lever. One end of the line wire is connected to the metallic base from which the current may pass through the pivots to the lever and thence to the small contact point attached to the underside of the lever; and the other end of the line wire is connected to the small insulated piece supporting the lower contact. By this arrangement no current can pass through the line until the key or lever is depressed. Since the terminal of the wire which is fastened to the lower contact is insulated, the current has no means of reaching the other part of the wire. When it is desired to send the current the handle is depressed, and the current generated in the battery, finding a passage between the two contacts, passes from one end of the wire to the other and proceeds upon the line wire to the distant station. Various modifications of this key are in existence, but in all the principle remains the same, that the electric circuit is closed or completed by the depression of a key. The length of time during which the handle is depressed determines the length of time between the upward and downward clicks of the sounder at the other end of the line. Thus if the operator presses down the handle and releases it quickly, the keeper of the sounder will go down and up, immediately indicating the letter "E," while if he presses the key and holds it down a moment before releasing it, there will be a longer interval between the downward and upper clicks of the sounder, and the letter "T" will be produced. In early instruments, before the operators had learned to read the messages by the clicks, the receiving instrument was arranged to make a record of the signals upon a moving strip of paper. For this purpose a pen or pencil was attached to the lever of the sounder, and a strip of paper, kept in motion by clockwork, was arranged to pass under the pen, so that a mark was produced by the pen every time the lever was pulled down by the magnet. If the lever was immediately released a dot was recorded, but if the lever was held down a moment a longer mark called a dash was produced. Fig. 2 shows such a recording Morse instrument with the letters “H. I.P." written upon the tape. It is of the most improved pattern, being arranged to start and stop the tape automatically. All of the delicate parts are under glass. The signals used at first were |