A NEW TELEPHOTOGRAPH SYSTEM 



571 



all d-c. repeater points and are actuated by the d-c. control circuit to 

 indicate when pictures are beinij transmitted over the network and 

 also the direction of transmission. 



The problems involved at junction points in connecting a number 

 of circuits, particularly of the 4-wire type, have been simplified 



TELEPHOTO- 

 GRAPH 

 STATION 



TELEPHOTOGRAPH 

 APPARATUS 

 REC SEND 



"I 



LOUD- PI 



SPEAKER LJ^^ 



4-WIRE 

 TALK 

 PAD SET 



RECEIVING 



&. SENDING 



RELAYS 



T V-tb^Y-TY TELEPHONE 



Jr'^--KEY--^|^ 



L J| REPEATING pi 



Lj COILS L_r 



CIRO^^^MA^ ^_... 

 COMPOSITE \ , U ^ |U 



L_(|<^OMPOSITE 

 LJ SETS 



4-WIRE CABLE CIRCUIT 



Fig. 14 — Schematic diagram of arrangements at a typical bridging point. 



through the use of a new form of bridging network. Although this 

 situation could be met by employing unilateral devices such as vacuum 

 tube amplifiers, it was found that comparable results could be obtained 

 simply and at less expense with interconnected resistance type pads. 

 Two designs of such networks, essentially alike except for the values 

 of attenuation provided, are in use, one for cable and the other for 

 open-wire circuits. These bridges are used not only at junctions of 



