TELEGRAPH. ELECTRIC. 



TELEGRAPH, ELECTRIC. 



7 



dark at the distant terminus wms required, WM either direct or indirect 

 in iu action. In the 6nt cue the attraction exercised by a borae-ahoe 

 piece of soft iron, rendered temporarily magnetic by the galvanic cur 

 rent, wa made to draw an armature, likewise of nft iron, towards it 

 and by tbi* action impel a small hammer againut a bell In the teconc 

 form of alarum, fy. 4, the movement of the armature merely released 



n.4. 



a detent or catch from a train of clock-work driven by a spring or 

 weight. Thii clock-work, by the intervention of a scape-wheel and 

 pallet*, rang the bell a* in a common alarum. 



In April, 1838, Mr. Cooke obtained a patent for some further im 

 provemente in this apparatus. Of these the most prominent was the 

 mode of introduction of the intermediate apparatus. Before the date 

 of these patent*, the two stations at the extremities of a line of tele 

 graph had alone been put in communication with each other; but 

 means were now devised by which any number of intermediate in- 

 struments might be introduced between the two terminals, and any 

 intelligence rendered simultaneously visible in all or in any of them, 

 as required. Furthermore any one of these instruments could be put 

 in communication with the rest, either generally or in part only ; and 

 the same mechanical adjustment which limited the connection of any 

 intermediate instrument to one part of the line, placed its bell in the 

 circuit of the other part. Thus if, while intelligence was being trans- 

 mitted in one direction from an intermediate station, some message of 

 importance were required to be sent from the terminus, or any other 

 station on the excluded side, the ringing of the bell at the communi- 

 cating station would warn the attendant to restore his instrument to 

 its intermediate position, and thus leave the line clear throughout. 



In the same patent were included some improvements on the mode 

 of protecting and insulating the wires, which were to be laid beneath 

 the earth, in tubes or troughs of wood, iron, earthenware, or other 

 material ; and also in the expedients for detecting the exact position 

 of any accident or derangement, without the necessity of uncovering 

 the whole length. Two needles were also shown to be sufficient for 

 carrying on a complete communication with ease and rapidity. 



In the course of the ensuing year (1889) Messrs. Cooke and Wheat- 

 stone'* telegraph was brought into actual operation upon the Great 

 Western Railway, where its capabilities were tested. The results of 

 this trial demonstrated that the undertaking was thus far successful, 

 and that the question of the practicability of the electric telegraph, so 

 long at iasue among scientific; men, was set at rest. 



We must here go back a little, to notice Dr. Steinheil's telegraph, 

 which was erected between Munich and Bogenhausen in 1837. In 

 this instrument, two needles or magnetic bars were placed within an 

 elongated coil of fine wire. These bars were suspended on axes passing 

 transversely across the coil, and in their quiescent position lay parallel 

 to one another and to the sides of the coil. They had their poles 

 placed the same way, ro that when a current was transmitted along 

 the win, they had a tendency to move in the same dire.-tion, remain- 

 ing still parallel to each other. Against the outer end of each n lie 



or bar a stop was placed, which checked its motion on one side, but 

 left it free to turn to the other. The opposite poles of the two Kin* 

 were therefore prevented from moving out from the coil, under the 

 influence of the deflecting current ; and the effect of this arrangement 

 was, that the two bars could not move simultaneously, but only alter- 

 nately. Both were acted upon alike, but when the inner < mi 

 was free to move outward, the other bar remained pressed agaii 

 Mop, and was fixed; and on reversing the current, the effect* upon 

 the two needle* were also reversed ; that which was before stationary, 

 now moved forward, while the other was fixed. In ,.,d,>r I 

 back the needles to their ordinary position, a permanent magnet was 

 fixed near to each at the back of the coil, by the attraction of which 

 the needle* were again rendered parallel after the cessation of the 

 detecting power of the current. The inner end* of these ban carried 

 each a light bras* arm, terminating in a cup furnished with a m. 

 foraied beak or .pout. These cups were filled with printing-ink, which 

 oond through the beak, and formed a minute bead or drop at ita point, 

 which, from it* vucid consutence. did not drop off. These beak* were 

 arranged so a* to be in the same horizontal line, and at a distance from 

 each other a little leas than the width of a strip of paper, which was 

 placed before them. If torn a galvanic current were passed throng, 

 the coil, so that the right-hand needle tended to pus, with the end 

 bearing the cup, out from the coil toward* the paper (the cup on the 

 other MUe receding as far a* the stop would allow, and then re- 

 mining fixed), the little beak would just touch the paper, and leave a 



minute dot of ink on its surface. By revening the current the other 

 needle would approach and leave a point of ink on the opposite edge of 

 the atrip of paper. By the varied number and arrangement of these 

 dot*, on one or both edge* of the paper, the various letters of any 

 communication wen denoted. The paper used in this apparatus, 

 being obtained in a long strip or ribbon, and coiled upon a roller, was 

 made to pass slowly lengthwise before the printing point* by a simple 

 application of a weight and cord, which a* the printing was effected 

 gradually wound the ribbon upon a second drum or reel. This > 

 ment was al*o adapted to give audible signals, by the substitnt 

 small knobs for the ink-cups, and of two bells of different tones for the 

 ribbon of paper. One bell being so placed a* to be sounded by tin- 

 first needle, and the other by the second, the pre-concerted combina- 

 tions of their sounds might indicate various letters to a listener. 



In the construction of his telegraph, Dr. Steiuheil made a capital 

 discovery. He found that the conducting power of the earth might be 

 made to occupy the place of the return wire. All that is necessary is. 

 that the wire which connects the two ends of the metallic conductor 

 with the earth, shall be carried to a sufficient depth below the surface 

 so as to be always in contact with moist earth or with water : and that 

 it shall be at this point attached to a plate or other piece of metal, of 

 about two or three feet superficial- For the ordinary Voltaic ! 

 Dr. Steinheil substituted the magneto-electric machine; in which, 

 according to Faraday's great discovery, the electric current was d. 

 by induction from a permanent magnet. 



The electric telegraph invented by I'rof. Morse, of America, has led 

 to a large amount of controversy, a claim having been put in for him 

 as the first actual inventor of a practical electric telegraph in 1832, 

 while on board the packet boat Sully. The Abbe' Moigno states that a 

 Mr. Jackson wrote to the Academic Francaise, affirming that be had, 

 in 1832, communicated this plan to Mr. Moise, while returning ! 

 from Europe to America, on board the Sully. K\vn admitting, b"v 

 the chums of either party, it would only show that they did not think 

 sufficiently well of their scheme to enter upon it until nearly 

 months after the first English patent for an electric telegraph bad been 

 sealed, and the practicability <>f Mich an apparatus demonstrated in 

 England. The first really official letter on the subject from Professor 

 Morse, is dated S> , 7, 1837. Cooke and Wheatatone's first 



patent for an electi sealed three months before this, 



namely, on June 1J, 1 <!7. The difference between this telegraph and 

 the preceding suggestions and contrivances was very great. The ex- 

 periments of these gentlemen Ij.id been proceeding for a lon.j 

 previously, so that when in June, 1837, their patent wag obtained, it was 

 not for an arrangement of doubtful practicability, or <-i' a foini to be 

 perfected only after repented trial. On the contrary it wa-s \\nliiii a 

 few months after the date of tin- patent, put up and brought int. > 

 and daily use. Some of its details have since been simplified, anil the 

 modes in which the electric current is made to give the required 

 indications have been greatly varied ; but the great features and prin- 

 ciples of their first invention remain unchanged, and not only no, but 

 they form an essential part of nearly if not quite all the later tele 

 graphs of other inventors. 



The telegraph exhibited by Morse in September, 1837, wag essen- 

 tially a registering instrument, the various signals being traced on a 

 strip of IHJXT. The plan appears to have been the following: an 

 electro-magnet was so placed as to be within attracting distance of an 

 armature fixed to the shorter arm of a lever, of which the long' 

 e.irried a pencil projecting sideways from it, and pressed lightly against 

 a sheet of paper. This p.i]>er. by ,1 contrivance analogous to that of 

 Dr. Steinheil, was made to travel slowly beneath the pencil. So long 

 as no attractive power wan exerted by the electro-magnet, the |>encil 

 would continue to trace a straight line as the paper moved onwards ; 

 but on momentarily making the circuit with the battery, the armature 

 was drawn to the electro-magnet, and the jieneil, carried by thorm of 

 the lever upwards, made an angular mark, like the letter V reversed, 

 on the paper. These angles might either be joined in groups, by 

 apiilly Huccceding completions of the .11,1111. or they might be sepa- 

 rated by longer or shorter spaces of straight line. The nine digits 

 were represented by corrcspoiiding numbers of angles, .ind 

 combined so as to form all possible numbers. A sl>rt space into 

 veiling between two or more successive groujw, denoted that thc\ 

 je taken together to form a total of two or .11- ; while 



a longer space showed the actual completion of one number and the 

 commencement of the next All the necessary words were represented 

 >y various numbers, as arbitrary signs, a previously arranged dictionary 

 >eing used for their interpretation. This plan had also been proposed 

 iy Mr. I; maids, to simplify the working of his telegraph. 



In the telcgiaph erected by Professor Mm-.-e, in 1>II. b, 

 Baltimore and Washington, a different mode of recording the signals 

 was adopted. The use of the pencil was found 



so frequently requiring fresh pointing, and from the risk of breakage. 

 The same arrangement* were retained in regard to the paper, > 

 was made in it* course to pass over a roller having a groove around it. 

 The long arm of the lever carried a blunt steel point, standing 

 the groove in the roller. When therefore the arm of the lever was 

 depressed, by the attraction of the magnet upon the armature, the 

 steel point pressed the paper into the groove, and produced an indenta- 

 tion. If the attraction were momentary, a depressed point was pro- 



