« ՆախորդըՇարունակել »
actions” for 1684. It consisted of 24 symbols the most used of which, until the introduction formed of blocks of wood, representing alpha- of the electric telegraph, was that adopted by betic characters, and 6 more formed of curved the admiralty in 1816. It was formed with two lines to be used as arbitrary signals. These were arms only, one at the top of a hollow hexagoto be exposed in succession in an elevated frame nal mast, and the other at some distance lower at some conspicuous point, and being observed down. Each of these arms admitted of 6 difat another station were to be there repeated ferent positions, easily distinguished from each and sent forward to the next, and so on. At other, and the two together could afford 48 sig. night torches or other lights were to be sub- nals, which are sufficient to express the letters stituted for the wooden figures. The first of the alphabet and the Arabic numerals, and working telegraph of much importance was leave 18 for other signs. The mast was made that known as Chappe's, which was brought to turn upon its foot, so as to display the sig- . into use during the wars of the French revolu- nals in any direction. For holding telegraphic tion. At the top of a tall post was attached a communication at sea, flags of various colors cross bar upon a pivot, so that it could be easily have long been used. (See SIGNALS.) It has been turned from a horizontal to an inclined position. proposed to employ a small helioscope or mirEach end of this cross bar carried a short arm, ror for reflecting a ray of light from the sun which could also be turned upon its pivot so as as a means of communicating signals in clear to stand in any position in relation to the bar. weather. With a mirror so small that it may The movements were made by means of ropes be carried in the waistcoat pocket, flashes of which passed through the bar and down the light may clearly be perceived for 12 miles or post. This apparatus admitted of 256 distinct more, and the mirror being gently moved on signals; but M. Chappe limited its use in great some established system the appearance and part to 16 signals, each one of which repre- disappearance of the flashes may indicate letsented a letter of the abbreviated alphabet he ters or words. Mr. Francis Galton, the African had constructed. The news of the recapture traveller, who proposed this at a meeting of of Lille was conveyed in 1794 by this telegraph the royal geographical society, described an to Paris in an hour after the troops of the re- optical arrangement he had devised by which public had entered the place. Mr. R. Lovell the operator may know if the mirror is directEdgeworth at about the same time brought be- ed aright. Among the later publications upon fore the public his plan of a telegraph, or as he the telegraphs adopted previous to the eleccalled it telelograph or tellograph, by which tric telegraph, are papers in the “Journal of the signals represented numbers, the meaning the Society of Arts," vols. xxvi., xxxiv., XXXV., of which would be found in the dictionary pre- and xxxvi.; “A Treatise explanatory of a new pared for this system. The signals were made System of Naval, Military, and Political Teleby means of 4 pieces of wood, each one in the graphic Communications," &c., by John Macform of a long isosceles triangle, placed near to- donald (London, 1817); “Description of the gether, each supported upon a pivot round which Universal Telegraph for Day and Night Sig. it could be turned in any direction. The move- nals,” by O. W. Pasley (London, 1823); and ments of each were limited to 8 in number, Edgeworth's “Essay on the Art of conveying and indicated the first 7 numerals and zero. Secret and Swift Intelligence,” in the “TransThe first triangle or pointer represented units, actions of the Royal Irish Academy," vol. vi. the 2d tens, the 3d hundreds, and the 4th -ELECTRIO TELEGRAPH. It would seem that thousands, so that any number might be ex- the idea of employing electricity for telegraphpressed that did not contain the figure 8 or 9. ing should soon have followed the discovery, The admiralty telegraph proposed by Lord G. made about the year 1729, that the shock could Murray was used in England from 1795 to 1816, be transmitted long distances through conductwhen it gave place to that known as the sema- ing media with great rapidity. But the attenphore (Gr. onua, a sign, and pepw, to carry), tion of the early experimenters was chiefly diwhich the French had adopted in 1803. This rected to some of the more obvious phenomconsisted of 6 conspicuous boards or shutters ena developed by the newly invented Leyden set in a frame, each of which could be turned jar, such as communicating the electric shock upon its axis so as to present either its edge or to a large number of persons in a continuous broad surface to the next station. The move- chain; the firing of alcohol by an electric charge ments represented figures, and a series of sent through wires under water, as performed numbers was indicated by their combinations. by Franklin across the Schuylkill river in 1748; Some of these stood for the letters of the al. the establishment of the identity of lightning phabet, and the others for arbitrary signals. and electricity, also determined by him at about The French semaphore (also known as signal the same time, &c. The electricity then known, posts) consisted of 3 or more arms attached by which was produced only by friction, disappearpivots to an upright post, admitting of motion ing with each discharge, was not at all adapted in any direction, and indicating by their va- for communicating signals, which requires a rious positions either figures or letters. Many continuous current. The various discoveries modifications of the apparatus were introduced which gradually led to the perfection of this into the
English navy, as well as upon the land, system, together with occasional experiments by Sir Home Popham and Capt. Ć. W. Pasley, relating to it, may be noticed in their chronological order. The discovery by Dr. Watson attention of the other operator to the letter in 1747, that the earth itself and intervening then in view. As the letters appeared in sucbodies of water might be made use of to com- cession they spelled out the message communiplete the electric circuit, was one important cated. The clock movement is an important step toward this application. He transmit- feature in most of the modern telegraph systed shocks across the Thames and the New teins. The voltaic pile, discovered in 1800, river, in one instance at Shooter's Hill the cir- furnished in its constant current a more promcuit being composed of 10,500 feet or about 2 ising agent for transmitting intelligence than m. of wire, and 2 m, of the earth; and he the sudden and transient shock of the electrical supported his wires, as now practised on the machine; and electricians were not long in telegraph lines, upon posts. Signals were testing its capacity for this purpose. Sömmercommunicated by means of the electric shock ing commenced his experiments in 1809, and from one apartment to another by Lesage at devised a plan of telegraphing which was as Geneva in 1774, and by Lomond in France in perfect as was practicable in the condition of 1787, probably by causing the divergence of the science at that time. He made use of 35 pith balls on some concerted plan; and in 1794 wires, each terminating in a gold point, and all Reizen of Germany employed the electric spark the points were set up vertically on a horizontal for telegraphing, making use of an ingenious line at the bottom of a glass reservoir of water. arrangement of lines and interrupted spaces In the other direction these wires, brought toupon strips of tin foil, so arranged that when gether in a tube, extended to the other station, these spaces were illuminated by the spark the where they again diverged, each one terminatform of the letter or figure was exhibited. Heing in a brass plate, and the plates attached employed 37 wires from one station to another, along a horizontal wooden bar. The plates at each one of them communicating with one of one end and the points at the other were the letters or figures, and each one connecting marked with corresponding letters, and the with a return wire, thus making 72 in all. This current from the battery was established whenplan is described in vol. ix. of “Voigt's Maga- ever two of the brass plates were touched, one zine." Cavallo in his “Treatise on Electricity” with the negative and one with the positive (1795) suggests the explosion of gunpowder to pole. Decomposition of the water immediately call attention, and then the transmitting of sig- occurred in the reservoir on the two correnals by succession of sparks at intervals and in sponding gold points, the one producing hydronumbers according to the system agreed upon. gen and the other oxygen gas, and the letters Don Francisco Salva of Madrid and Sr. Be- thus designated were noted down as part of tancourt constructed similar telegraphs at Ma- the message communicated. Sömmering found drid in 1797 and 1798, one of them extending that the addition of 2,000 feet of wire produced between Madrid and Aranjuez, a distance of little or no sensible additional resistance, and about 26 m. This, too, is noticed in vol. xi. of that the galvanic action was instantaneously the work just referred to. Salva communic developed at least for the distance of about cated his plans to the royal academy of sci- 3,000 feet. The galvanic batteries then known ences at Barcelona, and according to the jour- were however inapplicable to the transmission nals of 1797 they were highly approved by the of currents through great distances, both on minister of state. Salva appears to have had a account of not continuing long in action, and clear idea of the practicability of this electric also for want of sufficient intensity without communication even beneath the sea, and in using an inconvenient number of pairs; and the last of his memoirs he proposed to substi- no further progress was made in perfecting tute the voltaic pile for the electrical machine. the electric telegraph until the principles of Other attempts to employ machine or fric- electro-magnetism had been developed. (See tion electricity were made by Francis Ronalds ELECTRO-MAGNETISM.) The first discovery in at Hammersmith, England, in 1816, on a line this branch of science was that by Oersted of of 8 m.; and in 1827 by Harrison G. Dyar at Copenhagen, in 1819, of the electric current the race course on Long island, N. Y., on a as it passes through a wire causing a magnetic line of 2 m. in length. The latter made use of needle near by to place itself at right angles to iron wire, glass insulators, and wooden posts for the current, and that the direction of the movesupporting the wire, and employed the chem- ment may be changed by changing the connecical action of the electric current to change the tion of the wires with the two poles of the batcolor of litmus paper as his method of com- tery. Schweigger of Halle in 1820 discovered municating. Ronalds introduced the plan of the method of increasing the deflection by employing a clock at each of the two stations, placing the wire that carries the current around both of them running together exactly, and the needle, and this improvement is adopted in each bringing into view one after the other the all the telegraphs of this character. The same letters of the alphabet arranged upon a disk year Ampère laid before the academy of sciwhich revolved behind a screen with an open- ences at Paris the plan of a telegraph based on ing for one letter. Each clock was provided the movement of magnetic needles thus inwith two pith balls connected with the electrical duced. Each needle was to stand for a separate machine at the other station; and as the shock letter or figure, and consequently a great numwas passed the divergence of these called the ber was required. The early telegraphs of Prof. Steinheil of Munich, and of Cooke and needles, each of which corresponded to a Wheatstone of England, constructed many letter or figure, and was provided with its own years afterward, were based on this principle, wire of platinum insulated by being coverand were finally perfected by reducing the ed with silk, which wire surrounded the neenumber of wires. Ampère and Arago also dle on the principle of Schweigger's multidiscovered and put in practice the method of plier. The several wires beyond the multimagnetizing needles by passing the electric pliers were brought together into one cord, current in successive coils nearly at right angles and thence passed, to the next station. It aparound them, which is still employed in mak-pears that he succeeded in reducing the numing magnetic needles for compasses, &c. These ber of needles, and finally employed but one. discoveries, though preparing the way for the He also introduced an alarum at the comelectric telegraph, were yet insufficient; and mencement of the passage of the current by the opinion was even expressed in 1825 by Mr. causing a solid body to fall
, on the same prinBarlow, of the royal military academy of Wool- ciple as had been already recommended by wich, that in consequence of the diminishing Prof. Henry in his lectures. These promising power of the galvanic current with the increas- experiments were unfortunately interrupted ing distance, estimating the power from his ex- by his death, and the steps made were lost, periments as the square root of the length of without even a very accurate account being the wire, the construction of the telegraph preserved of the results attained. The next over long distances was impracticable. This experiments of importance were those of Counchecked further attempts for a time. The sellor Gauss and Prof. Weber of Göttingen in next discovery of importance was that of Mr. 1833 and 1834. They employed first galvanic William Sturgeon of London in 1825. By coil- electricity excited by numerous pairs, and afing copper wire loosely around a piece of iron terward a magneto-electric machine to transwire bent into horse-shoe form, with the turns mit signals from 9,000 to 15,000 feet. They of the copper wire quite separate from each caused a magnetic bar to be deflected to one other, and transmitting through this the gal- side or the other, and interpreted its repeated vanic current, he magnetized the iron, and thus movements into the letters of the alphabet; produced the first electro-magnet of 'soft iron. but no practical results followed their experiThis, however, was not applicable to telegraphic ments. `In 1836 the first form of the constant purposes, as from the open manner of coiling battery was invented by Prof. Daniell, supplythe naked wire to prevent the spires coming in ing the means of keeping up a continuous curcontact, sufficient power could not be generated rent. This principle is universally adopted through a long conductor to develop the mag- upon all telegraph lines, except those using the netic action necessary for closing the circuit, inductive current of Prof. Faraday's discovery, and thus producing a motion at will. Prof. in the form of the magneto-electric machine. Henry, in his experiments made in Albany, The first telegraph actually established apN. Y., in 1828–30, first employed a covered pears to have been that invented by Prof. O. wire, which could be wound in successive lay- A. Steinheil of Munich in 1836, and adopted ers upon itself round the whole length of an the next year by the Bavarian government. iron bar, either straight or bent into a U; and It extended a distance of 12 miles, employed he thus succeeded in so multiplying the mag- but a single wire, and made use of the earth to netic force, that with the use of a small bat- complete the circuit. The signals were sounds tery magnets were made of a power never be- produced upon a series of bells of different fore known, and the current was so increased tones, which soon became intelligible to a culin intensity, that the electric telegraph was at tivated ear; and the same movements that once made practicable for any distance. Upon caused the sounds were also made to trace all the telegraph lines except Bain's these elec- lines and dots upon a ribbon of paper moved tro-magnets are indispensable. The progress at a uniform rate, on the same principle with of discovery had now demonstrated the prac- the method devised about the same time by ticability of moving at will a magnetic needle Prof. S. F. B. Morse. The generator employed in one or the other direction, or of causing by Steinheil was a magneto-electric machine the armature of a magnet to be attracted and on the inductive principle discovered by Farathen released, and of repeating and varying day, but with the magnets stationary and the these movements rapidly for any number of multiplying coils revolving close to them. A times through wires extending any distance. current of more uniform flow was thus obtainThe possibility of an electric telegraph based ed than could be had with the voltaic pile. In upon either one of these two movements was 1837 several telegraphs were brought before thus established, and was recognized by elec- the public in different countries, the productricians; but to perfect it ingenuity of a high tion of independent inventors. That of Prof. order was to be called into play, together with Morse of the United States, which has continpatient study and much perseverance. The ued to be generally recognized in all parts of first person to apply to this object the dis- the world as the most efficient and simple, was coveries so far made was the baron Schilling first publicly exhibited in the university of New of St. Petersburg. He devised in 1832 a tele-York in 1887, and had been gradually brought graph on the principle of deflecting magnetic to a working condition by experiments and contrivances devised by the inventor since The slightness of the difference, which cannot 1832, with the assistance of Prof. L. D. Gale be avoided, between some of the signs, as in and Messrs. George and Alfred Vail. In Oct. the C and S, I and 0, L and T, &c., exposes to 1837, Prof. Morse filed a caveat in the patent mistakes, which in case of writing in cipher office to secure his invention; and he obtained cannot be corrected, and not always when the the patent in 1840, covering the improvements message is perfectly understood by the opera. he had in the mean time made in the apparatus. tor who sends it. Thus a merchant telegraphed The telegraph was first brought into practical from New Orleans to his correspondent in New use, May 27, 1844, between Washington and York, to protect a certain bill of exchange; Baltimore. An insulated wire was first tried the word "protect” was read as “protest," and buried in a lead pipe underground, and failing involved serious consequences to the parties was replaced with one on posts. The power interested. In the offices in the United States, was derived from a galvanic battery, and an where the Morse telegraph is employed, the iron electro-magnet was employed at the receive recording instrument is now generally abaning station for developing its effects. With the doned except at local and interior stations, and armature of the magnet was connected first & the operator trusts entirely to the sound pen with ink or a pencil for producing lines caused by the opening and breaking of the and dots upon a moving slip of paper, as the circuit. This saves the expense of an extra armature was drawn down to the two poles of assistant for reading the despatch to the copythe magnet on each closing of the circuit at ist, the operator now writing down the mes. the other station; the continued action of the sages as he receives them by the ear. Experibattery causing a line to be drawn as the paper ence has proved that a much smaller number moved along, and the immediate breaking of of errors are made in receiving by sound than the circuit after closing admitting of merely a by the former method of reading from_the dot. The combination of dots and lines to rep- strip of paper.- What is known as the Engresent letters and figures, and the simplicity and lish telegraph is the result of the investigaefficiency of the apparatus for producing these, tions and inventions of Mr. William F. Cooke, are the features which distinguish this from whose attention was directed to this subject other telegraphs, which employ the armature in March, 1836, when & student at Heidelmovement instead of the deflection of the nee- berg, by witnessing an experiment performed dle, and have led to the preference generally by Prof. Möncke of causing the deflection accorded to it throughout the world; and Mr. of a magnetic needle by the electric current. Morse is entitled to great credit for conceiving Though unacquainted with the subject, he this plan with the use of only one wire so early immediately set himself to work to apply the as 1832, and steadily adhering to it until he principle to the telegraph, and in July of had brought it to perfection. The apparatus that year he produced an experimental in. was improved by the substitution of a sharp strument, which he not long afterward took point for the pen or pencil, which is attached to England and sought to introduce on the to one end of a lever, at the other end of which Liverpool and Manchester railway. He the is the movable armature. The circuit is closed became associated with Prof. Wheatstone, by the operator who is sending a message press- and the two united their labors to perfect ing with his finger upon a single lever connect the instrument. The first patent for an eleced at its fulcrum with ono of the wires of the tric telegraph was issued to them on June battery, thus bringing it in contact with the 12, 1837. They employed 5 magnetic neeother pole, and the connection is instantly dles and coils, and either 5 or 6 wires, with broken for a dot, or allowed to continue a per- a peculiar key-board previously invented by ceptible period of time for a line. The paper Prof. Wheatstone, upon which were arranged of the registering apparatus is moved regularly the letters, and these were designated in turn along by clockwork. The signs for the letters as any two of the needles arranged across the in use for the English alphabet (which are va- centre of the board pointed to one and anriously modified to adapt them to other alpha- other of them. The apparatus underwent bets), and for the numerals and punctuation various modifications in the hands of its inmarks, are as follows, those most used, as will ventors, and was much simplified by the use be noticed, being the simplest:
of only two needles, and finally of only one, LETTERS.
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. NUMERALS.
Letters are designated by the deflection of the ::: 18 15
needle to the right or to the left one or more
times in either or both directions for each PUNCTUATION.
letter. The swinging of the needles is checkPerlod
ed by small pins fixed on the dial, so that Interrogation Parenthesis
their motions are rendered precise and clear. VOL. XV.-22
The magnetic coil has its own pair of wires, and other apparatus at each station, an expert one end running into the ground and the other operator can send as many as 150 letters a extending to the other stations, and with minute; but this is more than can be correctly these wires are also connected the batteries, by the limit of which is about 100 letters which communications are sent. In case of a minute, and in actual practice the number accident to the wire of one instrument, that of is somewhat less than this, or from 17 to 24 the other serves to keep up the communication. words a minute. Operators accustomed to the Handles placed in front under the dial furnish work do not require the lettered dial for read. the means by which the attendant can imme- ing the movements of the needle.--Of the nudiately connect the poles of the battery with merous telegraphic inventions that soon sucthe wires in either way, so as to cause the nee- ceeded those already named, Mr. Alexander dle to move to the right or to the left, and by Bain's are particularly worthy of notice. He partially turning them instantly reverse the was engaged in England as early as 1840 in the poles and consequently the direction of the production of a printing telegraph, and in 1846 movement of the needle; or he can by the patented what is known as an electro-chemical same apparatus interrupt the connection of telegraph, the principle of which was first aphis battery with the wires, in order to receive plied to this purpose by Harrison Gray Dyar communications. With each apparatus was in 1827, and by Mr. Edward Davy in England formerly connected an alarum bell, the clapper in 1838. Mr. Bain brought his new telegraph of which was moved by a weight or spring to the United States in 1849, and, after overconnected with clockwork, on this being set in coming the opposition made against it on the action by the electric current attracting the ground of its infringing the Morse patent, it armature of an electro-magnet, and thus was brought into active operation upon sevmoving a lever that held the apparatus in eral of the most important lines in the country, check. This is now generally abandoned, the and was the means of reducing the cost of telesound made by the click of the needle against graphing 40 per cent. The two interests were afthe ivory studs that prevent its vibration being terward consolidated, and the Morse patent was found sufficient. Prof. Wheatstone introduced adopted upon all the lines excepting that from one very important feature in the electric tele- Boston to Montreal. The Bain telegraph is regraph, which is a second battery for working markable for its extreme simplicity. No electhe alarum, and which has since been applied tro-magnet is required, the galvanic current to other purposes also requiring more power passing through the wire from a distant station than that furnished by the first battery. It is being sufficient to produce a distinct mark upon brought into action by the deflection of a the chemically prepared paper interposed bemagnetic needle, the ends of which are thus tween the point or index at the break in the placed in contact with the two wires of the circuit and the extension of the wire into the second battery, and so close its circuit. When ground. As this involves no change in the dithe current of the first circuit is interrupted, rection of the current, the same pole always the needle swings back, breaking the circuit remains connected with the earth, and the of the second battery and throwing it out of other (which must be the positive pole in order action. This is the principle of the relays em- to produce a colored mark upon the paper) is ployed to renew the power upon telegraph brought into connection with the line by closlines of great length. The telegraphs which ing the circuit with the key. The paper is are used upon the railways of Great Britain brushed over with a solution of 6 parts of prusand by the “Electric Telegraph Company" siate of potash in water, to which are added 2 are generally double, each employing its own parts of nitric acid and 2 of ammonia. Thus wires. One of the needles then indicates by prepared, and while damp, it is made to pass its movements the letters of one portion of over a metallic roller; a fine needle or style the alphabet, and the other the remaining presses gently upon the surface; a simple maletters. Two handles in the lower part of chine moved by clockwork to carry the strip the dial, one under each needle, serve for send- of paper is all that is required. The branch or ing the messages. The needles upon the dial local circuit of Morse can be applied as well are moved by the messages sent as well as by to this system for drop copies, or resistance those received, so that each operator may see coils can be used to effect the same object, the signals he makes. It thus appears that by producing with each closing of the circuit a the English telegraph no record is made by the line or å dot, on the principle of the Morse apparatus itself of the message; the operator and other similar systems. As it makes its observes the signs, and notes them upon paper marks instantaneously, however, without the as they succeed each other. It is thence some- intervening movement of an armature, it may times distinguished as the indicator telegraph, be made to communicate messages with much while the others are called registering tele- greater rapidity than the Morse telegraph. graphs. Morse's telegraph may be one or the It is observed of this system that it is not other, as it is used to prick the signals upon pa- in danger of disturbance during heavy thunder per, or as the operator interprets them by their storms, which occasionally do serious injury sound. With the English double-needle tele- to the operators as well as to the apparatus graph, employing two wires and two batteries employing the electro-magnet; and sufficient