256 



EXHIBITION OF ELECTRICITY AT PARIS. 



key of his instrument, he stops the current, and 

 the tuning-fork at the receiving-station ceases 

 to vibrate. A spring then draws against the 

 tuning-fork a contact-piece, which is usually 

 kept away by the vibrations. Through this 

 contact a local current passes which causes an 

 ordinary telegraphic sounder to respond to the 

 intervals in the vibration of the tuning-fork by 

 the long and short signals of the Morse alpha- 

 bet. If another tuning-fork at the sending- 

 station, vibrating at a different rate, is con- 

 nected with the wire, it will send currents at 

 each of its vibrations, which will act upon an- 

 other fork at the receiving-station, and cause 

 it to vibrate at the same pitch. This can be 

 connected with an independent battery and 

 sounder. On this ingenious plan as many as 

 five instruments can send messages over the 

 same wire in one direction, and five more in 

 the opposite, as fast as the ten operators can 

 work their instruments, without any interfer- 

 ence or confusion. 



The multiple type-printing telegraph of Bau- 

 dot is an ingenious improvement on the print- 

 ing-telegraphs of Edison and Hughes. In the 

 Hughes instrument there are twenty-eight ra- 

 dial arms connected with a key-board, before 

 which a metal contact-piece rotates rapidly. 

 At the receiving end the inked type-wheel 

 is moving in perfect synchronism, by means 

 of ingenious adjustments, with the clock-work 

 machinery at the other end. When a key 

 is struck, contact is made with the correspond- 

 ing radial arm, and a momentary current 

 passes, which brings in play the electro-me- 

 chanical apparatus at the receiving end, and 

 causes the paper to be lifted instantaneously 

 against the type on the wheel corresponding to 

 the note struck on the key-board. The rapid 

 response of the armature to the current is se- 

 cured by a new relay arrangement, called the 

 Hughes magnet, in which the armature is kept 

 in contact with the poles, but is suddenly drawn 

 away by a spring when the current passes, and 

 weakens the magnet. In Baudot's system five 

 signals are variously combined to give the 

 twenty-six letters of the alphabet, and five 

 other signs. An arm bearing thirty contact- 

 springs revolves in front of thirty contact- 

 pieces, so that thirty signals can be transmit- 

 ted at each revolution. Six operators have 

 control of five contact-pieces each. At the re- 

 ceiving end there are six machines, with five 

 electro-magnets and armatures in each, which 

 are set in action by the momentary signal-cur- 

 rents. By an admirable mechanical arrange- 

 ment the signals are translated automatically, 

 and the proper letters printed evenly upon a 

 strip of paper. A radial arm, rotated about its 

 center, carries five points which press against 

 a flat plate, which pressure prevents the arm 

 from turning upon its axis under the influence of 

 a spring. The points are moved a little to one 

 side or the other by triangles, which are actu- 

 ated by the armatures. In the plate are de- 

 pressions, aad when all the points strike a de- 



pression at the same time, a partial revolution 

 of the arm about its axis takes place. This 

 causes the revolving type-wheel to impress the 

 letter indicated by the combination upon the 

 paper. It is found easier by the operators to 

 make the combinations themselves on a key- 

 board with five keys, than to use one with a 

 note for each letter and sign. With Baudot's 

 apparatus six messages can be sent on one wiro 

 at the same time, at the rate of twenty-tlnvo 

 words a minute each. 



Autographic telegraph instruments have not 

 yet been found practically useful. They would 

 be a valuable aid in strategic operations, as 

 maps and plans could thus be sent in fac- 

 simile by telegraph. The message is written 

 on a surface of tin-foil or other metal, w hich is 

 connected with the earth. The ink is some 

 substance which acts as an insulator. The tin- 

 foil on which the message is written is given 

 a uniform motion, under a style which has a 

 transverse motion. The marker and the paper 

 on which the message is reproduced have a 

 corresponding and exactly synchronous move- 

 ment at the other end of the wire. When the 

 style touches the ink on the tin-foil, a current 

 passes. In the instruments of Caselli and 

 D'Arlingcourt the marker is an iron point, 

 and rests upon paper impregnated with ferro- 

 cyanide of potassium. This is decomposed by 

 the electric current, leaving a blue mark. 

 Meyer uses ordinary paper and an inked 

 marker, which is brought in contact with 

 the paper by the action of the current. A 

 message of 145 words is reproduced by D'Ar- 

 lingcourt's instrument in five and a quarter 

 minutes. 



Edison's autographic telegraph has several 

 advantages over the other devices of the class, 

 the chief of which is that the sender of a dis- 

 patch has no difficulty in preparing his mes- 

 sage, as he does when he must write it with a 

 thick, fatty ink, or other unusual materials. 

 Edison's apparatus consists of two instruments 

 exactly alike, in which are two cylinders 

 that revolve synchronously, being actuated 

 by electric motors and regulated by conical 

 pendulums so disposed as to keep perfect time 

 with each other. On the cylinder of the re- 

 ceiver is wound a sheet of chemically prepared 

 paper. The dispatch is written on soft paper 

 with a rather hard lead-pencil. A narrow 

 plate moving slowly along the cylinder is 

 pierced by a hole into which fits a steel point. 

 This point traverses the entire sheet of paper 

 in a spiral line. On the smooth paper it is on 

 a level with the lower surface of the plate ; 

 but when it crosses the mark of the pencil it 

 falls into the groove made in the paper. This 

 displacement of the point is made to produce 

 an electric contact and to send a current to 

 the other end, where a blue mark is made on 

 the paper of the receiver every time, and as 

 long as the metallic point is in the depressed 

 track of the pencil. 



Of the brilliant series of electric inventions 



