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BELL SYSTEM TECHNICAL JOURNAL 



of the system is: 



A/ = £ ( ,rL + — ) g-(T+nx at the sending end, 

 okK. 16 



M' 



A' + Z 



UK 

 where X = (r — s), 



16 



g-l(.y-v)x+ri] at the distant end, 



Y = 2(a -b - c + d) + (e-f), 

 Z — {m — n — p -\- q), 



and the positive direction in both circuits is the same as in con- 

 ductor 1. 



III. Repeater Circuits * 



The following points seem to merit an experimental trial. 



1. A Two-way Repeater Circuit Including Two Repeaters, Each Operating 

 as a One-way Repeater Only, as Illustrated by the Following Sketch 



With this circuit the allowable unbalance is about double that with 

 our present standard circuit. In addition to this, singing will not be 

 introduced by any possible unbalance, however large, in either of the 

 lines, provided the unbalance of the other line does not exceed a certain 

 critical magnitude. Furthermore, the two lines connected together 

 may differ radically in character since each is balanced separately 

 against its own artificial line. 



The present standard circuit or any one of several other repeater 

 circuits may be substituted in place of the basic circuit shown in this 

 sketch. 



Although the circuit requires that all of the repeating apparatus be 

 duplicated and that two artificial lines (of which at least one must be 

 a close copy of the corresponding actual line as regards telephonic 



* Dated March 7, 1912. 



