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TELEGRAPH. ELECTUIC. 



TELEGRAPH. ELECTRIC. 



the required locality ; and 3rd, the apparatus by which at the distant 

 end of the line, the existence of thU power, iu amount, or the direc- 

 tion of iu action, U made known to the observer. In the earlier stages 

 of the invention, the investigation* of iU promoters were confined to 

 the hut of theae three essentials ; and BO long a* the illustration of the 

 idm m confined to the lecture-table, this part claimed pre-eminm . v. 

 But. with the proposed application of the principle to purposes of 

 general utility, there arose the necessity for an equal degree of atten- 

 tion to the two former requisites. 



The experiments of Dr. Watson in England, in 1747, and of Franklin, 

 iu 1748, on the banks of the Schuylkill river, may have suggested 

 the conveyance of information by means of electricity. The earliest 

 authenticated instance of any attempt to reduce this idea to practice, 

 appears to have been that of M . Lesage at Geneva, in 1 7 7 4, and of Lomond 

 in France, in 1 787. They employed as an indicator a pair of pith Kill*. 

 suspended from one end of an insulated wire, at the other end of which 

 was the operator, provided with an electrical machine. On charging 

 the wire with electricity, the pith balls would exercise mutual repul- 

 sion, and diverge from one another ; but on removing the electrical 

 charge from the wire by the contact of some conductor, the balls 

 would collapse. It is evident that certain numbers of successive 

 divergences might be made to denote particular preconcerted signals. 

 Subsequently to this, the phenomenon of the spark, as seen on the 

 passage of electricity through an uninterrupted conductor, was used 

 for the transmission of signals. Were the various letters of the alpha- 

 bet formed in this manner, upon a table, and connected each one with 

 a distinct and insulated wire, any particular letter might be rendered 

 visible in a darkened room, by passing an electrical charge through the 

 appropriate wire. This in fact constituted the telegraph of Beusser, 

 or Keuer, invented in 1794. Betancourt and Dr. Salva in Spain, in 

 1798, appear to have made experiments on the transmission of the 

 charge through wires of great length. 



A somewhat similar form of apparatus, involving the same principle, 

 was constructed by arranging the several wires in succession, with a 

 single break in each. The various wires bore the names of the dif- 

 ferent letters or figures, and any required signal was indicated by 

 passing the charge through the proper wire, when the spark visible at 

 the interruption of the circuit would denote the letter to the observer 

 at the farther end. 



This was the point to which the invention had advanced, at the 

 nent of the present century. The discovery by Volta, in 



1800, of the pile which bears his name, forms the commencement of a 

 new era in electric telegraphs, although there was no immediate 

 application of the phenomena of the galvanic current to the purpose. 

 Indeed siveral important discoveries had to be made before an electric 

 telegraph of any value was possible. 



In 18u7, Summering at Munich proposed to construct an electric 

 telegraph on the principle of the decomposition of water by the 

 Voltaic current, as discovered in 1800 by Nicholson and Carlisle. The 

 form of his apparatus was the following : In a glass trough containing 

 water, thirty-five gold pegs or pins were arranged vertically, this 

 number of pegs corresponding to the letters of the alphabet, together 

 with the nine digits. Each of these pins was connected with a wire, 

 which extended to the place whence the signal was to be transmitted. 

 At this point they terminated in brass strips, arranged iu a frame side 

 by side, but, like the wires and pins, insulated from each other. Each 

 His* strip bore the name of the letter or figure which belonged to the 

 pin to which it was connected. The operator, when wishing to send 

 any communication, connected the two poles of the battery with the 

 brass strips bearing the names of the two first letters required. 

 Decomposition of the water in the trough at the distant end was 

 instantly indicated by the evolution of bubbles of gas from the two 

 gold pins, which thus became the two electrodes or poles of the 

 battery. The letters funning any communication were to be in this 

 manner denoted in pairs, the inventor ingeniously availing himself 

 of the different quantities of the two gases evolved to point out 

 the relative position of the letters in each pair, the hydrogen being 

 employed to indicate the first letter. Schweigger proposed to add to 

 thin system a plan for calling the attention of the correspondent at 

 the distant station by the discharge, by the current, of a pistol charged 

 with the mixed gases. 



In 1816, Mr. Ronalds, of Hammersmith, invented an electric tele- 

 graph, in which the use of frictiooal electricity was recurred to. This 

 telegraph, which was shown to several scic-ntili.- men at the date above 

 givro, wa* fully described by the inventor in a work published by 

 him in 182%. Mr. Ronalds employed the divergence and collapse 

 of a pair of pith-balls as the telegraphic indication, in which respect 

 the principle was the same as that adopted by Mr. Lomond ; l,ut 

 to thto simple apparatus, a distinct contrivance was appended, in 

 order to render the communication more rapid and easy. A single 

 wire, perfectly insulated by being suspended from silken strings, or 

 buried in glass tubes, surrounded by pitch, and protected by wooden 

 troughs, was extended between the two stations. From the end of 

 this wire was suspended in front of the dial of a clock a pair ol 

 pith-balls, so that while the wire was charged the bolls would remain 

 divergent, but would instantly collapse, when the wire by contact 

 with the earth, or with the hand of the operator, was discharged. A 

 at one end baring therefore an electrical machine by which 



he could maintain the wire in an electrified state, and the pith-bolls 

 at the farther extremity consequently in a state of divergence, had 

 t of course in liis power to give an instantaneous indication to an 

 observer at that farther extremity by touching the wire with his 

 :iand, which, discharging the electricity, would allow the ball* to col- 

 lapse for an instant. But instead of merely employing the successive 

 movements of the pith-balls to denote the various signals, Mr. Bonalds 

 added another apparatus for this purpose. Two clocks, very accu- 

 rately adjusted to the same rate of going, carried, instead of the 

 ordinary seconds hand, light discs, on which the various letters of tin- 

 alphabet, the figures, and other required signals were engraved. These 

 discs turned with a regular step by step movement, behind a screen 

 of metal, in which was mode a small opening, sufficient to allow of 

 one letter at a time being seen. As the discs turned round, each 

 letter in succession would be visible through this space; and it is 

 evident that if the clocks were started with the same signal visible, 

 the movement of the discs would bring similar signals into view at 

 the same tune. One of these instruments was situated at eacl 

 of the communicating wire. The operator who was about to trans- 

 mit any communication, watched the dial of his clock until the letter 

 he required was visible, snd at that instant discharged the wire. The 

 momentary collapse of the balls at the distant end would then warn 

 the observer to note the letter visible on his instrument, which would 

 form a part of the intelligence to be received. The successive ! 

 or signals constituting any message were denoted in this manner as the 

 clock dials continued to turn round. In order to avoid the ne 

 for constant attention on the part of the observer, an arrangement 

 was adopted by which a pistol could be fired by the Bjmrk at (hi: 

 farther end, to summon the attendant to his instrument. \ 

 signals were also concerted beforehand, by the use of which (lie 

 time necessary for the transmission of any intelligence was lessened. 

 These experiments of Mr. Bonalds' were made with the in' 

 tion of several miles of wire, carried backward and forward across 

 hie grounds. 



In 1819, Professor Oersted of Copenhagen made his great dis- 

 covery of the action of the galvanic current upon a magnetic- needle. 

 He observed that when a current is passed along a wire, placed 

 parallel and near to a magnetic needle, free to turn on its centre, the 

 needle is deflected to one side or the other, according to the direc- 

 tion in which the current is transmitted. He fmt 1 that 

 the position of the wire, whether above or below the needle, had an 

 equal influence with the direction of the current in determining the. 

 side to which the deflection took place. [Ei.ECTBO-DvNAMics.] The 

 power of a single wire in causing this deviation of a needle is but 

 small, but this was remedied by the invention of the mitlti/>liu-,r 

 (' u. NANOMETER, by Professor Schweigger, in which the needle, being 

 surrounded with many successive coils of insulated wire, is acted upon 

 by the joint force of all. Under a somewhat different form, this dis- 

 covery now forms the basis of the needle electric telegraph. 



Very shortly after this important discovery had been made, Arago 

 and Ampere in France, and Seebeck in Berlin, succeeded in rendering 

 iron magnetic, by the passage of a galvanic current through a wire 

 coiled around the iron, and Sturgeon in England produced the first 

 electro-magnet. [ELECTRO-MAGNETISM.] It was found that, provided 

 the iron to be magnetised were perfectly soft and pure, the magnetic 

 property remained only during the actual transmission of the elec- 

 tricity, and was lost immediately on the interruption of the electric 

 circuit. If the iron which was exposed to the influence of the galvanic 

 current were combined with sulphur, carbon, or phosphorus, the 

 magnetic power became to a greater or less extent permanent iu it. 



The invention of the voltaic battery, of the deflection of the needle, 

 and of the magnetisation of soft iron, formed the three great steps in the 

 history of the electric telegraph. 



M. Ampere suggested the employment of the discovery of Oersted as 

 early as 1830, and this suggestion was acted upon by 1'r. 

 Bitchie, in a model telegraph exhibited by him at the Royal Institu 

 tion. Ampere's plan however was far from possessing the simplicity 

 so essential iu an instrument designed for practical use. Not less than 

 thirty pairs of conducting wires were necessary, according to his 

 scheme, for maintaining a telegraphic communication. 



Baron Schilling also, in Prussia, in 1832 and 1833, following the i lea 

 originated by Ampere, proposed a similar form of telegraph, in wliich 

 there were as many of these galvanometers, each with its .ippmp -iatc 

 circuit, as there were letters or signs to be used in the various com- 

 munications. In fact there were 36 needles and 7- wires. In 

 Gauss and Weber proposed to employ the separate movements of a 

 suspended bar as signals : but its indications must have been feeble, as 

 they had to be observed through a telescope placed at some distance 

 from the oscillating bar. In 1837, M. Alexander exhibited a model of 

 a proposed form of telegraph, containing 25 needles, to be acted upon as 

 in Ampere's arrangement. In this instrument a distinct needle was 

 employed for the indication of each letter, these needles bearing at "i- 

 end light screens of paper, which concealed from view a letter or figure, 

 until by the deflection of the needle the screen was removed, and the 

 letter brought into sight. M. Alexander, however, effected one great 

 improvement, in substituting a single return wire, to which one end of 

 all the coils was joined for the several distinct return wires existing in 

 the previous invention of M. Schilling. At a later period this gentle- 



