

8o Telephone Systems of the Continent of Europe 



pressing the key DI cuts the indicator out and the operator's set 

 os in. F3 is a plug connected to earth through the indicator M4, 

 the calling key KI, the vibrator v, and the battery B. This is for 

 calling on the Van Rysselberghe circuits ; for use on ordinary 

 lines there is another plug F4 and key K2 which brings a magneto 

 generator G into play, c is a wire common to all the sections of 

 the local multiple, by which all communications between the local 

 and trunk operators are exchanged, ci is one of the wires of a 

 metallic circuit subscriber connected to earth through the jack J3. 

 02 03 are two junction wires going to one of the local sections ; 

 they are connected through the two jacks 14 J5, which are within 

 reach of all the trunk operators, four in number. The local 

 operators communicating with the trunk table are provided with 

 the apparatus shown in fig. 18, in which D2 is a Dewar key in the 

 circuit of the common wire c coming from the trunk table ; K3 a 

 key which when depressed puts the magneto G in connection with 

 c ; 03 another Dewar key in circuit with the wire 03 ; M5 an in- 

 dicator, one side of which is joined to 02 and the other to earth. 

 F5 is a double plug the inner contact of which is in permanent 

 connection with 03, while its outer contact connects with C2. A 

 calling current from the line wi W2 (fig. 17) operates the phonic 

 call which drops an indicator not shown in the diagram. To 

 reply, the button KI is pressed, which brings the vibrator v into 

 action through the primary TP of the translator and earth, currents 

 being transferred to the line by induction through the secondaries 

 TI T2. The speaking set os is then cut in by pressing the key DI. 

 When a single-wire subscriber wants a trunk connection he drops 

 his indicator and states his demand. The local operator rings the 

 trunk on c by pressing K3 (fig. 18), and immediately puts down 

 the Dewar key D2. The trunk girl, on the fall of indicator M3 

 (fig. 17), depresses her key and finds herself speaking with the 

 other. On hearing the demand she indicates which junction wire, 

 say 03, is to be used. The local girl then puts the plug F5 (fig. 18) 

 into the local subscriber's jack. The trunk girl calls the distant 

 station by pressing the button KI (fig. 17), and inserts the plug 

 F3 into one of the jacks J4 75 and says ' speak.' By pressing 

 her key DI she can hear by induction the commencement of the 

 talk. When finished, each subscriber rings off and the indicator 



