TELEGRAPH, ELECTRIC. 



TELEGRAPH, ELECTRIC. 



curreut in either direction, BO as to deflect the distant needle either to 

 the right or to the left at pleasure, some such arrangement as the 

 following is necessary. There are many arrangements, more or less 

 simple, having the same object in view, but we give this one for the 

 t.ikc of illustrating the principle : Fly. 13 represents the galvanometer 

 coil, with its needle, n t, at rest, or in a position to receive a message. 

 Now, suppose the current from the distant battery to enter the coil G 

 by the wire L. It will pass through the coil and come out by the 

 left-hand wire connected with a metallic spring, v. It will then pass 

 along the brass cross-piece d to the metallic spring t, and complete the 

 circuit by means of the wire attached to the earth-plate P, and the 

 earth, by which it returns to the distant station. The battery c z, 

 at the receiving station, remains inactive, its extreme wires being 

 attached to insulated pieces of brass at either end of the vertical piece 

 connected with d. Hence no current can pass, since the wire from c 



Tia.U. 



Fis.14. 



fig. 15. 



is insulated. If, however, a signal hag to be transmitted from this 

 instrument to the distant station, the clerk works the handle in front 

 of the instrument, and presses d against the spring t, fy, 14, whereby 

 the lower extremity of the bran piece ia brought into contact with the 

 other spring, v, and the current now pane* in the direction of the 

 arrow*, that is, from c to v, through the wire attached to p, into 

 the earth through the distant station, where the instrument is arranged 

 for receiving the signal, as injiy. 13, where it produces a deflection of 

 the needle ; the current then returns by L to the galvanometer coil o, 

 deflects the needle, and returns by the wire attached to the spring (, 

 and o by the metallic piece d, through the wire attached to z, and thus 

 completes the circuit. By reversing the motion of the handle, the 

 direction of the current, and the motion of the needleg in the coil, will 

 lie reversed, both in the near and in the distant instrument, as in Jiy. I a. 

 When the clerk has finished making hia signals, the springs v and t 

 restore the cross-piece d to the position shown in fy. 1 3, so that the 

 instrument adjusts itself for receiving signals from the distant station, 

 the battery c z ia thrown out of action, and the conducting communi- 

 cation with the line is restored by mean* of the cross-piece </. In this 

 way the tame motion of the needle is produced at the same instant at 

 both stations, so that the sender and the receiver of the message each 

 perceives the signals. 



There is in general but one needle in connection with each galvano- 

 meter coiL The astatic arrangement formerly adopted is not now in 

 use ; the outside needle, by which the clerk knows how the signals are 

 proceeding, being formed of ivory, or some inert substance, attached to 

 the same axis which carries the magnetic needle within the coil. The 

 needles are limited in their motions by means of small ivory studs fixed 

 in the dial, and they are thus prevented from swinging too far over, 

 while their motions are made precise and clear. It was formerly the 

 practice to give a preparatory notice of a message to the distant station 

 by ringing the electric alarum, but this was found to be so intolerable 

 to the persons in waiting that it has been abandoned, and the clicking 

 sound of the needle against the ivory studs is sufficient to draw the 

 attention of the clerk to the arrival or passing of a menage. When a 

 menage is sent from London to York, for example, all the needles of 

 the intermediate stations are similarly deflected ; but each clerk knows, 

 *by a special signal, when he is required to be spoken with. There are, 

 however, contrivances called " commutators," by which a message is 

 made to pass any one or more stations without entering them. In 

 thi way intermediate stations may communicate with each other ; 

 otherwise, they would have to remain idle while two exterior stations 

 were communicating with each other. Of course, the larger the 



number of stations which can communicate with each other simul- 

 taneously, the larger must be the number of the wires. 



When the instrument consists of two needles and two coils the 

 alphabet may be made out somewhat in the following manner. Calling 

 the left-hand needle No. 1, and the right-hand No. 2, and indicating 

 one movement of either needle to the left by I, and one movement to 

 the right by r, the combinations of movements which stand for the 

 various letters of the alphabet are the following : 



Of course it is possible to form an alphabet with one needle and one 

 wire only ; the communication is not so rapid as with two wires and 

 two needles, but the construction of the line is more economical, and 

 the system is adapted for use between places of second-rate importance. 

 Various alphabets and modes of signalling have been contrived with a 

 view to celerity, and some of these are ingenious. We select one by 

 the Rev. H. Highton, as described by Mr. E. Highton : a small slip of 

 gold leaf inserted in a glass tube is made to perform part of the electric 

 circuit of the line wire, and near it is a permanent magnet. When a 

 current of electricity is passed along the line wire, the gold leaf is 

 instantly deflected to the right or to the left according to the direction 

 of the current. Now supposing the deflection of the gold leaf to the 

 left signified the figure 1, and the deflection to the right the figure 3, 

 we have the alphabet made up in the following manner : twice to the 

 right, or 33, signifies A ; twice to the left, once to the right, and once 

 to the left, or 1131 =B ; 311 = C ; 133 = D ; a single signal to the left, 

 or 1 = E ; thus acting on the correct principle of representing the 

 letters of most frequent occurrence by the most rapidly executed 

 signals; K 313, O 1133, H 113, I 31, J 3133, K 1331, L 331, M 1113, 

 N 13, 11, P 1111, Q 1313, R 333, S 111, T 3, U 131, V 1311, W 1333, 

 X 3113, Y 3111, Z 3131. A motion to the left signifies " Do under- 

 stand," and one to the right " Not understand." " Repeat " is ex- 

 pressed by 3331, and " Wait " by 3333. 



Steinheil suggested the plan of receiving telegraphic signals by means 

 of two bells, one muffled and the other free, to be struck by the needle 

 or needles when deflected by two currents. This pkn has been adopted 

 by Sir Charles Bright on the relay system, with a local battery to 

 supply the mechanical power required to strike the bells. This is 

 used at the principal ' stations of the British and Irish Magnetic Tele- 

 graph Company. The transmitting instrument is a key invented by 

 Highton, consisting of a couple of springs, one marked + and the 

 other , connected one with the earth and the other with the line. 

 When these springs are at rest, or pressing upwards, the line and the 

 , earth are in connection with one another, and with the positive pole of 

 the battery, the negative pole being insulated. When the earth-spring 

 marked +, is pressed down by the finger, the earth connection is 

 thrown on the negative pole, and the positive pole is left on the tele- 

 graph line, which thus receives a positive current. When the line- 

 spring marked is pressed down, the positive pole of the battery is 

 left in connection with the earth, and the line is thrown into connec- 

 tion with the negative pole of the battery, and will thus receive a 

 negative current. Now it is perfectly easy to make the two bells take 

 the place of the gold strip, and calling the left-hand bell 1, and the 

 right-hand bell 3, Highton 's nomenclature becomes applicable. The 

 receiving-clerk is seated between the two bells, and his ear being alone 

 engaged in receiving the signals, he can write down the letters which 

 they represent as easily as when one clerk is employed to watch the 

 needle, and dictate the message to another who writes it down. 

 Whether this system may not induce an increased amount of nervous- 

 ness in the clerks employed, we are not able to say, but it is stated 

 that the use of the ordinary needle telegraph is apt to produce nervous 

 irritability in the clerks who are long employed upon it. 



A considerable advance has recently been made in telegraphs in con- 

 sequence of Professor Wheatstone's copious list of improvements in 

 the whole of the telegraphic system, embodied in two patents dated 

 2nd of June, 1858, and numbered respectively 1239, 1241. We give 

 these numbers in order that persons interested in the subject may the 

 more readily procure the printed copies of the specifications, which are 

 accompanied the one by six and the other by ten sheets of illustrative 

 engravings. The basis of this invention is the Letter Telegraph of 1 839, 

 now called the Unherml Telegraph; and it is so simple in its action 

 that no training is required to use it; for the message may either be 

 spelt out on a dial by bringing common letters opposite a fixed point, 



