actions" for 1684. It consisted of 24 symbols formed of blocks of wood, representing alphabetic characters, and 6 more formed of curved lines to be used as arbitrary signals. These were to be exposed in succession in an elevated frame at some conspicuous point, and being observed at another station were to be there repeated and sent forward to the next, and so on. At night torches or other lights were to be substituted for the wooden figures. The first working telegraph of much importance was that known as Chappe's, which was brought into use during the wars of the French revolution. At the top of a tall post was attached a cross bar upon a pivot, so that it could be easily turned from a horizontal to an inclined position. Each end of this cross bar carried a short arm, which could also be turned upon its pivot so as to stand in any position in relation to the bar. The movements were made by means of ropes which passed through the bar and down the post. This apparatus admitted of 256 distinct signals; but M. Chappe limited its use in great part to 16 signals, each one of which represented a letter of the abbreviated alphabet he had constructed. The news of the recapture of Lille was conveyed in 1794 by this telegraph to Paris in an hour after the troops of the republic had entered the place. Mr. R. Lovell Edgeworth at about the same time brought before the public his plan of a telegraph, or as he called it telelograph or tellograph, by which the signals represented numbers, the meaning of which would be found in the dictionary prepared for this system. The signals were made by means of 4 pieces of wood, each one in the form of a long isosceles triangle, placed near together, each supported upon a pivot round which it could be turned in any direction. The movements of each were limited to 8 in number, and indicated the first 7 numerals and zero. The first triangle or pointer represented units, the 2d tens, the 3d hundreds, and the 4th thousands, so that any number might be expressed that did not contain the figure 8 or 9. The admiralty telegraph proposed by Lord G. Murray was used in England from 1795 to 1816, when it gave place to that known as the semaphore (Gr. onua, a sign, and pepo, to carry), which the French had adopted in 1803. This consisted of 6 conspicuous boards or shutters set in a frame, each of which could be turned upon its axis so as to present either its edge or broad surface to the next station. The movements represented figures, and a series of numbers was indicated by their combinations. Some of these stood for the letters of the alphabet, and the others for arbitrary signals. The French semaphore (also known as signal posts) consisted of 3 or more arms attached by pivots to an upright post, admitting of motion in any direction, and indicating by their various positions either figures or letters. Many modifications of the apparatus were introduced into the English navy, as well as upon the land, by Sir Home Popham and Capt. Ĉ. W. Pasley,

the most used of which, until the introduction of the electric telegraph, was that adopted by the admiralty in 1816. It was formed with two arms only, one at the top of a hollow hexagonal mast, and the other at some distance lower down. Each of these arms admitted of 6 different positions, easily distinguished from each other, and the two together could afford 48 signals, which are sufficient to express the letters of the alphabet and the Arabic numerals, and leave 13 for other signs. The mast was made to turn upon its foot, so as to display the sig-. nals in any direction. For holding telegraphic communication at sea, flags of various colors have long been used. (See SIGNALS.) It has been proposed to employ a small helioscope or mirror for reflecting a ray of light from the sun as a means of communicating signals in clear weather. With a mirror so small that it may be carried in the waistcoat pocket, flashes of light may clearly be perceived for 12 miles or more, and the mirror being gently moved on some established system the appearance and disappearance of the flashes may indicate letters or words. Mr. Francis Galton, the African traveller, who proposed this at a meeting of the royal geographical society, described an optical arrangement he had devised by which the operator may know if the mirror is directed aright. Among the later publications upon the telegraphs adopted previous to the electric telegraph, are papers in the "Journal of the Society of Arts," vols. xxvi., xxxiv., xxxv., and xxxvi.; "A Treatise explanatory of a new System of Naval, Military, and Political Telegraphic Communications," &c., by John Macdonald (London, 1817); "Description of the Universal Telegraph for Day and Night Signals," by C. W. Pasley (London, 1823); and Edgeworth's "Essay on the Art of conveying Secret and Swift Intelligence," in the "Transactions of the Royal Irish Academy," vol. vi. -ELECTRIC TELEGRAPH. It would seem that the idea of employing electricity for telegraphing should soon have followed the discovery, made about the year 1729, that the shock could be transmitted long distances through conducting media with great rapidity. But the attention of the early experimenters was chiefly directed to some of the more obvious phenomena developed by the newly invented Leyden jar, such as communicating the electric shock to a large number of persons in a continuous chain; the firing of alcohol by an electric charge sent through wires under water, as performed by Franklin across the Schuylkill river in 1748; the establishment of the identity of lightning and electricity, also determined by him at about the same time, &c. The electricity then known, which was produced only by friction, disappearing with each discharge, was not at all adapted for communicating signals, which requires a continuous current. The various discoveries which gradually led to the perfection of this system, together with occasional experiments relating to it, may be noticed in their chrono

logical order.

The discovery by Dr. Watson in 1747, that the earth itself and intervening bodies of water might be made use of to complete the electric circuit, was one important step toward this application. He transmitted shocks across the Thames and the New river, in one instance at Shooter's Hill the circuit being composed of 10,500 feet or about 2 m. of wire, and 2 m. of the earth; and he supported his wires, as now practised on the telegraph lines, upon posts. Signals were communicated by means of the electric shock from one apartment to another by Lesage at Geneva in 1774, and by Lomond in France in 1787, probably by causing the divergence of pith balls on some concerted plan; and in 1794 Reizen of Germany employed the electric spark for telegraphing, making use of an ingenious arrangement of lines and interrupted spaces upon strips of tin foil, so arranged that when these spaces were illuminated by the spark the form of the letter or figure was exhibited. He employed 37 wires from one station to another, each one of them communicating with one of the letters or figures, and each one connecting with a return wire, thus making 72 in all. This plan is described in vol. ix. of "Voigt's Magazine." Cavallo in his "Treatise on Electricity" (1795) suggests the explosion of gunpowder to call attention, and then the transmitting of signals by succession of sparks at intervals and in numbers according to the system agreed upon. Don Francisco Salva of Madrid and Sr. Betancourt constructed similar telegraphs at Madrid in 1797 and 1798, one of them extending between Madrid and Aranjuez, a distance of about 26 m. This, too, is noticed in vol. xi. of the work just referred to. Salva communicated his plans to the royal academy of sciences at Barcelona, and according to the journals of 1797 they were highly approved by the minister of state. Salva appears to have had a clear idea of the practicability of this electric communication even beneath the sea, and in the last of his memoirs he proposed to substitute the voltaic pile for the electrical machine. Other attempts to employ machine or friction electricity were made by Francis Ronalds at Hammersmith, England, in 1816, on a line of 8 m.; and in 1827 by Harrison G. Dyar at the race course on Long island, N. Y., on a line of 2 m. in length. The latter made use of iron wire, glass insulators, and wooden posts for supporting the wire, and employed the chemical action of the electric current to change the color of litmus paper as his method of communicating. Ronalds introduced the plan of employing a clock at each of the two stations, both of them running together exactly, and each bringing into view one after the other the letters of the alphabet arranged upon a disk which revolved behind a screen with an opening for one letter. Each clock was provided with two pith balls connected with the electrical machine at the other station; and as the shock was passed the divergence of these called the

attention of the other operator to the letter then in view. As the letters appeared in succession they spelled out the message communicated. The clock movement is an important feature in most of the modern telegraph systems. The voltaic pile, discovered in 1800, furnished in its constant current a more promising agent for transmitting intelligence than the sudden and transient shock of the electrical machine; and electricians were not long in testing its capacity for this purpose. Sömmering commenced his experiments in 1809, and devised a plan of telegraphing which was as perfect as was practicable in the condition of the science at that time. He made use of 35 wires, each terminating in a gold point, and all the points were set up vertically on a horizontal line at the bottom of a glass reservoir of water. In the other direction these wires, brought together in a tube, extended to the other station, where they again diverged, each one terminating in a brass plate, and the plates attached along a horizontal wooden bar. The plates at one end and the points at the other were marked with corresponding letters, and the current from the battery was established whenever two of the brass plates were touched, one with the negative and one with the positive pole. Decomposition of the water immediately occurred in the reservoir on the two corresponding gold points, the one producing hydrogen and the other oxygen gas, and the letters thus designated were noted down as part of the message communicated. Sömmering found that the addition of 2,000 feet of wire produced little or no sensible additional resistance, and that the galvanic action was instantaneously developed at least for the distance of about 3,000 feet. The galvanic batteries then known were however inapplicable to the transmission of currents through great distances, both on account of not continuing long in action, and also for want of sufficient intensity without using an inconvenient number of pairs; and no further progress was made in perfecting the electric telegraph until the principles of electro-magnetism had been developed. (See ELECTRO-MAGNETISM.) The first discovery in this branch of science was that by Oersted of Copenhagen, in 1819, of the electric current as it passes through a wire causing a magnetic needle near by to place itself at right angles to the current, and that the direction of the movement may be changed by changing the connection of the wires with the two poles of the battery. Schweigger of Halle in 1820 discovered the method of increasing the deflection by placing the wire that carries the current around the needle, and this improvement is adopted in all the telegraphs of this character. The same year Ampère laid before the academy of sciences at Paris the plan of a telegraph based on the movement of magnetic needles thus induced. Each needle was to stand for a separate letter or figure, and consequently a great number was required. The early telegraphs of

Prof. Steinheil of Munich, and of Cooke and Wheatstone of England, constructed many years afterward, were based on this principle, and were finally perfected by reducing the number of wires. Ampère and Arago also discovered and put in practice the method of magnetizing needles by passing the electric current in successive coils nearly at right angles around them, which is still employed in making magnetic needles for compasses, &c. These discoveries, though preparing the way for the electric telegraph, were yet insufficient; and the opinion was even expressed in 1825 by Mr. Barlow, of the royal military academy of Woolwich, that in consequence of the diminishing power of the galvanic current with the increasing distance, estimating the power from his experiments as the square root of the length of the wire, the construction of the telegraph over long distances was impracticable. This checked further attempts for a time. The next discovery of importance was that of Mr. William Sturgeon of London in 1825. By coiling copper wire loosely around a piece of iron wire bent into horse-shoe form, with the turns of the copper wire quite separate from each other, and transmitting through this the galvanic current, he magnetized the iron, and thus produced the first electro-magnet of soft iron. This, however, was not applicable to telegraphic purposes, as from the open manner of coiling the naked wire to prevent the spires coming in contact, sufficient power could not be generated through a long conductor to develop the magnetic action necessary for closing the circuit, and thus producing a motion at will. Prof. Henry, in his experiments made in Albany, N. Y., in 1828-30, first employed a covered wire, which could be wound in successive layers upon itself round the whole length of an iron bar, either straight or bent into a U; and he thus succeeded in so multiplying the magnetic force, that with the use of a small battery magnets were made of a power never before known, and the current was so increased in intensity, that the electric telegraph was at once made practicable for any distance. Upon all the telegraph lines except Bain's these electro-magnets are indispensable. The progress of discovery had now demonstrated the practicability of moving at will a magnetic needle in one or the other direction, or of causing the armature of a magnet to be attracted and then released, and of repeating and varying these movements rapidly for any number of times through wires extending any distance. The possibility of an electric telegraph based upon either one of these two movements was thus established, and was recognized by electricians; but to perfect it ingenuity of a high order was to be called into play, together with patient study and much perseverance. The first person to apply to this object the discoveries so far made was the baron Schilling of St. Petersburg. He devised in 1832 a telegraph on the principle of deflecting magnetic

needles, each of which corresponded to a letter or figure, and was provided with its own wire of platinum insulated by being covered with silk, which wire surrounded the needle on the principle of Schweigger's multiplier. The several wires beyond the multipliers were brought together into one cord, and thence passed, to the next station. It appears that he succeeded in reducing the number of needles, and finally employed but one. He also introduced an alarum at the commencement of the passage of the current by causing a solid body to fall, on the same principle as had been already recommended by Prof. Henry in his lectures. These promising experiments were unfortunately interrupted by his death, and the steps made were lost, without even a very accurate account being preserved of the results attained. The next experiments of importance were those of Counsellor Gauss and Prof. Weber of Göttingen in 1833 and 1834. They employed first galvanic electricity excited by numerous pairs, and afterward a magneto-electric machine to transmit signals from 9,000 to 15,000 feet. They caused a magnetic bar to be deflected to one side or the other, and interpreted its repeated movements into the letters of the alphabet; but no practical results followed their experiments. In 1836 the first form of the constant battery was invented by Prof. Daniell, supplying the means of keeping up a continuous current. This principle is universally adopted upon all telegraph lines, except those using the inductive current of Prof. Faraday's discovery, in the form of the magneto-electric machine. The first telegraph actually established appears to have been that invented by Prof. Ĉ. A. Steinheil of Munich in 1836, and adopted the next year by the Bavarian government. It extended a distance of 12 miles, employed but a single wire, and made use of the earth to complete the circuit. The signals were sounds produced upon a series of bells of different tones, which soon became intelligible to a cultivated ear; and the same movements that caused the sounds were also made to trace lines and dots upon a ribbon of paper moved at a uniform rate, on the same principle with the method devised about the same time by Prof. S. F. B. Morse. The generator employed by Steinheil was a magneto-electric machine on the inductive principle discovered by Faraday, but with the magnets stationary and the multiplying coils revolving close to them. A current of more uniform flow was thus obtained than could be had with the voltaic pile.-In 1837 several telegraphs were brought before the public in different countries, the production of independent inventors. That of Prof. Morse of the United States, which has continued to be generally recognized in all parts of the world as the most efficient and simple, was first publicly exhibited in the university of New York in 1887, and had been gradually brought to a working condition by experiments and

contrivances devised by the inventor since 1832, with the assistance of Prof. L. D. Gale and Messrs. George and Alfred Vail. In Oct. 1837, Prof. Morse filed a caveat in the patent office to secure his invention; and he obtained the patent in 1840, covering the improvements he had in the mean time made in the apparatus. The telegraph was first brought into practical use, May 27, 1844, between Washington and Baltimore. An insulated wire was first tried buried in a lead pipe underground, and failing was replaced with one on posts. The power was derived from a galvanic battery, and an iron electro-magnet was employed at the receiving station for developing its effects. With the armature of the magnet was connected first a pen with ink or a pencil for producing lines and dots upon a moving slip of paper, as the armature was drawn down to the two poles of the magnet on each closing of the circuit at the other station; the continued action of the battery causing a line to be drawn as the paper moved along, and the immediate breaking of the circuit after closing admitting of merely a dot. The combination of dots and lines to represent letters and figures, and the simplicity and efficiency of the apparatus for producing these, are the features which distinguish this from other telegraphs, which employ the armature movement instead of the deflection of the needle, and have led to the preference generally accorded to it throughout the world; and Mr. Morse is entitled to great credit for conceiving this plan with the use of only one wire so early as 1832, and steadily adhering to it until he had brought it to perfection. The apparatus was improved by the substitution of a sharp point for the pen or pencil, which is attached to one end of a lever, at the other end of which is the movable armature. The circuit is closed by the operator who is sending a message pressing with his finger upon a single lever connected at its fulcrum with one of the wires of the battery, thus bringing it in contact with the other pole, and the connection is instantly broken for a dot, or allowed to continue a perceptible period of time for a line. The paper of the registering apparatus is moved regularly along by clockwork. The signs for the letters in use for the English alphabet (which are variously modified to adapt them to other alphabets), and for the numerals and punctuation marks, are as follows, those most used, as will be noticed, being the simplest:

The slightness of the difference, which cannot be avoided, between some of the signs, as in the C and S, I and O, L and T, &c., exposes to mistakes, which in case of writing in cipher cannot be corrected, and not always when the message is perfectly understood by the operator who sends it. Thus a merchant telegraphed from New Orleans to his correspondent in New York, to protect a certain bill of exchange; the word "protect" was read as "protest," and involved serious consequences to the parties interested. In the offices in the United States, where the Morse telegraph is employed, the recording instrument is now generally abandoned except at local and interior stations, and the operator trusts entirely to the sound caused by the opening and breaking of the circuit. This saves the expense of an extra assistant for reading the despatch to the copyist, the operator now writing down the messages as he receives them by the ear. Experience has proved that a much smaller number of errors are made in receiving by sound than by the former method of reading from the strip of paper.-What is known as the English telegraph is the result of the investigations and inventions of Mr. William F. Cooke, whose attention was directed to this subject in March, 1836, when a student at Heidelberg, by witnessing an experiment performed by Prof. Möncke of causing the deflection of a magnetic needle by the electric current. Though unacquainted with the subject, he immediately set himself to work to apply the principle to the telegraph, and in July of that year he produced an experimental instrument, which he not long afterward took to England and sought to introduce on the Liverpool and Manchester railway. He there became associated with Prof. Wheatstone, and the two united their labors to perfect the instrument. The first patent for an electric telegraph was issued to them on June 12, 1837. They employed 5 magnetic needles and coils, and either 5 or 6 wires, with a peculiar key-board previously invented by Prof. Wheatstone, upon which were arranged the letters, and these were designated in turn as any two of the needles arranged across the centre of the board pointed to one and another of them. The apparatus underwent various modifications in the hands of its inventors, and was much simplified by the use of only two needles, and finally of only one, which may be but a wooden pointer. This is arranged upon the middle of a vertical tablet through which the axis it turns on passes to the electro-magnet that is secured on the back of the tablet, and within which is the real needle that causes the movement. Letters are designated by the deflection of the needle to the right or to the left one or more times in either or both directions for each letter. The swinging of the needles is checked by small pins fixed on the dial, so that their motions are rendered precise and clear.