NEUTR.UJZ.ITIDN OP TEJ.r.GR.im CROSSFIRE 



429 



The result of transposing is that for practical purposes in connection 

 with the crossfire problem the other wires of the line can be ignored 

 and a phantom group represented by a network of admittances as 

 shown in Fig. 8, where 1 and 2 represent a i)air and 3 and 4 the other 

 pair. 



A network of the form of Fig. 8, is used as shown in Fig. 9, for 

 neutralizing sending-end crossfire among the four wares of a phantom 



t 90 Volts 

 Grounded 

 Batteries 



Receiving-end Crossfire Neutralizer 



■4-windinq trarisformer; mutual 

 inductance = 0.8 henri/ between 

 edch pair of^ vHndinqs;cuTent from 

 odd to even numbered terminal5 

 qnetizes core in same 

 -idireclionr 

 nail 

 Cdtet, 



Polar Duplex Seli 



Fig. 10— Arrangement for neutralizing crossfire between telegraph circuits on a 

 loaded No. 13 B.&S. Ga. phantom group 90 to 120 miles long in cable 



group. The grounded branches shown in Fig. 8 are omitted, however, 

 since the duplex artificial lines themselves constitute these branches. 

 The six-mesh network consists of condensers, the timing resistances 

 w^hen used being external to the network as a matter of convenience. 

 For coupling together the apex circuits of the four wires to neu- 

 tralize receiving-end crossfire, it is possible to use a special four- 

 winding transformer analogous to the six-condenser network, but 

 where an ordinary transformer as shown in Fig. 10 will not sufifice 

 it is convenient to employ two or three transformers in combination. 

 For example a two-winding transformer may be added to each pair 

 of the arrangement illustrated in Fig. 10 so as to pro\ide additional 

 coupling between the two wires of a pair. 



