230 Telephone Systems of tJie Continent of Europe 



trunks chiefly concentrate, there is a special trunk table fitted for 

 fifty lines. The key-board is shown in fig. 78. It is mounted 

 with ten pairs of double-conductor plugs and cords, i to x, each 

 pair being connected to a key i to 10. Six of these keys i, 2, 

 3, and 8, 9, 10 are joined to the keys TI T2 T3 and T8 TQ Tio r 

 which bring the translators (of the Landrath pattern) into circuit. 

 By turning down the switches A and c the key-board is divided 

 into two sections and may be attended to by two operators ; when 

 A and c are up and B down one operator can control the whole. 

 LI to 14 are listening keys, and cut off one side of a connection 

 when the plugs are in ; RI to R4 are ringing keys. Fig. 79 (with 



FIG. 7 



the same reference letters) is a diagram of the general connections. 

 The spring-jacks may have attached to them either metallic 

 circuits or single earthed wires ; thus w v z are metallic trunks 

 and x an earthed wire going to the main switch-board for joining 

 to the subscribers' single lines. It will be seen that the table 

 allows of all necessary combinations i.e. direct connection of two 

 metallic circuits, of two single wires, and of a metallic with a single 

 either through a translator or direct. 



Subscribers are asked for by numbers ; after receiving the 

 operator's intimation that the connection has been made, the 

 caller hangs up his phone, and himself rings his client's bell. 

 After the talk is over he rings off in the ordinary way. When a 

 subscriber is called he takes down his phone and speaks without 



