428 



BELL SYS'ILM TLCUNICAL JOURNAL 



It should l)c nolcfl that in addition to the reduction in couplin.u; due 

 to increasing the spacing there is a large reduction due to shielding 

 when a third conductor is interposed between two others. 

 I In the case of cable circuits the wires are twisted in groups of four 

 so as to be transposed practically continuously. On account of the 



Fig. 8 — Admittance Network 



smaller separation, mutual capacitances and the resulting crossfire 

 among wares of a phantom group, are considerably greater than in 

 open wire. 



Fig. 9 — Condenser arrangement for neutralizing sending-end crossfire between tele- 

 graph circuits on a phantom group 



