TKLKURAPH, 1 



TELEGRAPH, Dl.DTRIC. 





conducting ivory, whereby tie current U alternately transmitted and 

 interrupted. A radiating vm prooeedi from each letter (or the con- 

 venience of turning the din. If the disc stand to that its stop-mark + 

 b opposite toa fixed mark, the spring is rating on an ivory piece, and 

 if at the same moment the index of the distant telegraph in connection 

 with it be also pointing to the + , then on moving the communicator 

 on* (top forward, o that the letter A cornea to the fixed mark, 

 the current will be transmitted along the wire, the electro-magnet, 

 jif. 8, will draw down it* armature no as to pull the wheel one tooth 

 'forward, and make its index alao point to the letter A. On again 

 moving the communicator eo that the index point* to n, the current u 

 interrupted, the armature of the distant telegraph falls back, pitching 

 the wheel round another tooth, and bringing iU index also to B. In 

 this way the index may be moved step by step to different letters so as 

 to spell out a word or message, which word or message will be repeated 

 on the disc of the distant telegraph. A slight pause is made after each 

 letter of the message, to insure certainty ; numerous modifications have 

 been made in this machine, for increasing the rapidity of its action. An 

 addition of printing mechanism to this instrument forms the type- 

 printing telegraph. In this the escapement axis, instead of carrying a 

 fixed due, has light radiating arms of steel, at the ends of which are 

 printing-types a.Jiyt. 10, 11. In front of the types is a small roller or 



Fig. 10. 



. 11. 



plate 6, for receiving the blow of a printing-hammer c, which stands 

 behind the type disc. The paper which receives the impression is placed 

 between the roller and the type disc, which paper is coiled on the 

 roller </, and is drawn off by passing between two other rollers e, which 

 hold the paper tightly and turn a little way round after each blow 

 of the hammer. 



The action is as follows : The type-disc U turned round by alter- 

 nately transmitting and interrupting the current until the proper 

 letter U brought into the proper position to be struck, when, the 

 hammer being released, it presses the type on the paper. The drawing- 

 rollers immediately jerk the papers forward through a space equal to 

 that of one letter, when the type-disc U again moved onward to the 

 next letter required, which is struck in like manner, and so with all 

 the rest of the letters in the message. The hammer usually strikes 

 by the force of a spring, which is released by the train which acts upon 

 the drawing-rollers. The mechanism is so contrived that the hammer 

 cannot strike while the type-disc is in motion, but falls as soon as a 

 pause is made, that is, when the right letter is brought into position. 

 The types are inked by means of a small roller smeared with printing- 

 ink, which, as the type-disc revolves, proas IMI lightly against their sur- 

 faces. Or a ribbon of carbonic ink transfer-paper may be drawn 

 round between the typo-disc and the white paper ribbon. Numerous 

 variations have been made in the type-printing telegraph, the best 

 known of which is by Mr. linin. In this machine the types were 

 arranged on the edge of the disc or wheel, radiating from its centre ; 

 ami the printing of any one upon the cylinder was effected by the 

 movement forward of the entire type-wheel and its axis, by a crank 

 and connecting gear in the printing train, instead of one punch or type 

 nly being struck down by the printing-hammiT, in impressing a signal. 

 It was also proposed to use two clocks at the two communicating ela- 

 tion*, to rotate the type-wheels with a uniform motion. These clocks, 

 having been adjusted to exactly the same rate, and being started from 

 the same signal, would bring continually, at each station, similar type 

 opposite to the paper-cylinders at the same moment. The action of 

 this part of the apparatus is exactly analogous to that of Mr. Ronalds', 

 already described. A hand or index revolving on a dial in front of the 

 ~**'~ at the same rate as the type-wheel, indicates to the operator 

 UM signals which are successively hi a position ready for printing in 

 his own instrument, and therefore, if the clocks go accurately together, 

 in a similar position in his correspondent's instrument. At the same 

 time this hand, by coming in contact in its revolution with a pin 

 placed by UM operator opposite to any signal that he wishes to 

 print, compUtos the electric circuit at this moment, and by so doing 

 stops the type-wheel, snd releases the printing-train at each station. 

 A similar figure having thus been impressed on the cylinder at the 

 two rods of the line, the operator remove* the pin, and replace! it 

 opposite the next signal be requires to send. The moment the pin in 

 removed, and the circuit therefore broken, the hands and type-wheels 

 at each station muroe their evolutions which are again checked by 



the contact of the hand and pin as before. It should 1* stated that 

 the idea of the two clocks, as well as that of the printing-telegraph, was 

 borrowed from WheaUtone. 



Bain's tin : ,lr-iilts telegraph, which was the instrument proposed by 

 him for practical use, consisted of two hollow cylindrical coils of wire, 

 placed horizontally a short distance apart, with their axes in the same 

 line. Between them a small bar-magnet was fixed across a delicate 

 spring, which in front passed through the dial-plate of the instrument, 

 and was turned up to form an index. The two coils were connected, 

 so that an electric current entering from the line wire would pass 

 through both. When this was the case, the bar-magnet would be 

 attracted towards one coil, while at the same time it would be repelled 

 by the other. These actions tended to carry the magnet to the same 

 side, as far as the spring to which it was attached and a fixed stop 

 would allow of its moving. The reversal of the current im rrtl the 

 effects of the coils, and the magnet would then pass to UP 

 The combinations of these two movements represented the various 

 letters and signals, they being denoted to the observer by the index on 

 the dial of the instrument. The movement of the index to tl 

 denoting the letter I, and to the right the letter V, this instrument 

 obtained the name of ' I and v Telegraph.' 



In 1842, Mr. Bain patented his proposed plan for working an electric 

 telegraph by means of an earth batter;/. At one end of the line he 

 buried in moist earth a large plate of zinc, and at the ntluT end a 

 plate of copper, iron. r other substance such as coke or charcoal, 

 which might act the part of a negative plate to the zinc. Then, on 

 connecting these distant plates with a wire insulated from the earth , a 

 current of electricity would constantly pass from the one plate to the 

 other. Indeed, the distant plates connected with the wire, a> 

 described, may be regarded merely as a battery of one pair of plates, 

 separated by a very wide interval of exciting material, represent 

 the earth. It was at first supposed by Mr. Bain that this current 

 would be applicable to all telegraphic purposes, but subsequent experi- 

 ments showed that it was available only for a few miles of distance ; 

 iie intensity not being sufficient to enable it to travel through any great 

 length of wire. In some cases, where a constant current of low inten- 

 sity is required, this earth battery might be of use. 



In 1843, Mr. Cooke introduced the mode of extending the wires 

 between distant places, so that their insulation from one another, and 

 from the earth, might bo maintained without the expense and difficulty 

 hitherto incurred ; be-fore this period the wire* having been covered 

 with cotton, and insulated by coating them with shell-lac, re&in, or 

 pitch, had been laid down in pipes of wood or iron. It waa now 

 proposed to insulate the wires by suspending them in the air upon posts 

 or standards of wood or iron, the wires not coming in actual contact 

 with any part of the standard, but passing through rings of porcelain 

 or earthenware. [Glass was afterwards found to be the best insulator.] 

 The standards were usually fixed at from forty to sixty yards asunder, 

 and at each quarter of a mile a stouter post was placed, to bear the 

 winding or straining apparatus. This was a simple winding-reel, con- 

 nected with a ratchet-wheel and click to prevent its recoil, after the 

 wire had been strained up by its means. The intermediate pasta 

 within each quarter of a mile only supported the wire, without 

 ence to its tension, which depended solely on the winding posts. 

 Instead of the copper wires hitherto employed, iron wires of a larger 

 size were now used. By the adoption of this method of extending the 

 conducting wires, the cost of construction of an electric telegraph was 

 reduced nearly one-half, and at the same time the risk of imperfect 

 insulation was diminished. So long as the wires were buried in tubes 

 beneath the ground, it wan always deemed pnulent to add a return 

 wire, extending from one end of the line to the other ; as it was found 

 very difficult to render the insulation sufficiently good to enable the 

 earth itself to be used as half of the circuit. The tendency of the 

 electric fluid to escape from the wires in the tubes to the earth, was 

 much greater than to another wire lying in the same tube, so that the 

 latter plan was always adopted. But when the suspended conductors 

 came into operation, the insulation was rendered so complete, that the 

 earth was subsequently in all cases used to return the current, by 

 which means an economy of one wire throughout the whole line was 

 effected. In addition to this, another advantage was gained by the 

 suspension of the wires, in the facility with which accidental errors or 

 injuries were discovered and rectified. While the tubes were in use, 

 it was necessary to supply, at about each quarter of a mile along the 

 line, a proving or testing pout, within which the wires were brought 

 up to a box, so as to afford the means of examining any of them as to 

 their insulation and conducting power. For thi* purp"sc, Mr. Cooko 

 hod invented an instrument called the detector, liy \vlipli the perfect 

 state of each wire could be tested, and the position of any error or 

 fault discovered with considerable accuracy. .Still, with all these 

 appliances, the detection and repair of any derangement of the wires 

 demanded considerable skill, and led to no small expense. But when 

 the wires were in sight throughout, any contact or fracture was at once 

 visible, and was easily and quickly repaired. 



We must here pause in the attempt to trace the history of this 

 great invention through the medium of its patents. The reader wlm 

 is desirous of pursuing the subject in this way, is referred to one of 

 the valuable volumes printed by order of the Commissioners of 

 Patents, mtitliil ' Abridgments of B] us relating to Electricity 



