NA TURE 



[May 30, 1 90 1 



transmitting and receiving instruments ; these are con- 

 nected as a single loop earthed at each end, thus providing 

 three distinct circuits since currents can be sent through 

 either of the two wires to return by earth or can be sent 

 through one wire to return by the other. The general 

 principles of the apparatus will be understood from Figs. 

 I and 2. Fig. i is from a photograph of the instrument 

 with the cover and paper removed in order to show the 

 working parts. It will be seen from this photograph that 

 the complete apparatus consists both of a transmitting 

 instrument, fixed on the horizontal baseboard, and a 

 receiving instrument, supported on the four upright 

 pillars. Fig. 2 is a diagram of the connections, only the 



Fig. I. — General \ie\v of the Telautograph. 



principal connections being shown in order to avoid a 

 multiplicity of lines. 



When the operator wishes to send a message he takes 

 up the transmitting pencil, .\, and with the point shifts to 

 the left the catch c. This operation actuates a grip 

 which shifts the paper forward at both ends of the line, 

 thus bringing up a clean piece to write upon, and also 

 connects up the transmitting and disconnects the receiving 

 apparatus at the home end. At the same time, it reverses 

 the connections of one of the sets of batteries, two sets 

 of which are used, one at each end of the line, which are 

 normally connected in opposition so that when the con- 

 nections of one set are reversed by shifting the catch c 

 they are connected in series. The operator now proceeds 

 to]write on the transmitting paper : the pencil, .\, is con- 



NO. 1648, VOL. 64 J 



nected to two sets of levers, ll, which actuate the sliding 

 contacts of two rheostats, RR' ; these rheostats are 

 connected one in series with each of the two lines, R in 

 the line EwwE', and r' in the line ew'w'k'. As the re- 

 sistances of the rheostats are varied by the motion of the 

 sliding contacts corresponding to the motion of the pencil, 

 A. the currents in the two lines will vary. These currents 

 pass through and deflect the moving coils of two galvano- 

 meters of the d'Arsonval type, G, g', in the receiving in- 

 strument ; these coils are connected by two sets of levers, 

 LI,', to the receiving pen, P. It will thus be seen that 

 the position of the pen i: is controlled by the deflections 

 of the two gal vanometers, which are in their turn dependent 

 on the position of the trans- 

 mitting pencil A : the pen will 

 therefore exactly follow in its 

 motions the movements of the 

 pencil and will consequently 

 repeat on the paper at the 

 receiving end the drawing made 

 on that at the transmitting end. 

 The currents, after traversing 

 the coils of G and ('.', pass through 

 the relays u and d' (the use of 

 which will be explained pre- 

 sently) and then return by earth. 

 From what has been said so 

 far it is obvious that the re- 

 ceiving pen will copy the move- 

 ments of the pencil a, whether 

 the pencil is being used to write 

 on the paper or merely being 

 moved about above it. It is 

 necessary to prevent the pen i; 

 from making marks on the paper 

 except when a is actually writing 

 on the paper at the transmitting 

 end. This is effected in the 

 following ingenious manner. A 

 small induction coil at the trans- 

 mitting end has its primary 

 circuit, P, completed through a 

 contact, M, attached to the desk 

 on which the writing paper rests: 

 the terminals of the secondary 

 coil, s, are connected to the line 

 wires, w,w', and the circuit is 

 completed at the receiving end 

 through the relay H and the 

 condenser k'. Intermittent cur- 

 rents are thus sent round the 

 circuit swHw's and, actuating 

 the relay H, put in action a pen 

 lifting magnet (not shown in 

 the diagram) which raises the 

 bar F and holds the pen 1; off 

 the paper. When the operator 

 starts writing the pressure on the 

 paper breaks the contact at M and thus stops the vibratory 

 currents ; the relay H is released and the bar F falls back, 

 thus allowing the pen to come into contact with the receiv- 

 ing paper. It will be noticed that the vibratory currents are 

 superimposed on the ordinary line currents, but they are 

 prevented from affecting the receiving pen by the self- 

 induction of the galvanometer circuit, whilst at the same 

 time the line currents are prevented from passing through 

 the relay H by the condensers k and k'. A small amount 

 of the intermittent current does pass through the galvano- 

 meter coils, but this is, as a matter of fact, advantageous, as 

 it prevents, by the slight vibration it produces, any 

 tendency to sticking. 



When the writer has filled up the strip of paper he 

 again shifts the clutch C and this moves forward the 



