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BELL SYSTEM TECHNICAL JOURNAL 



the grounded capacity of the pair, neither of which is changed by the 

 assumed method of balancing. 



As illustrated in Fig. 6, terminals 1, 2 are the given pair and terminal 

 3 includes all others, assumed to be connected together. A bridge 

 ratio of unity is employed, and the entire bridge is shielded from 

 ground with the exception of corners (?, 2) which are initially balanced 



Fig. 6 — Bridge for Determining Hypothetical Capacity Between Two Terminals 

 with Other Terminals Balanced and Ignored 



to ground within the range of variable condenser /. The following 

 two successive balances are made: 



1. With contacts a, a' closed and h open, balance is secured by 

 varying condenser / (the total capacity of which is constant) 

 giving the reading C for its direct capacity in parallel with 

 terminals 1, 3. 



2. With contacts a, a' open and h closed, balance is obtained by 

 varying condenser //, obtaining the reading C" for its direct 

 capacity in (S'2). 



If Co, C'l are the corresponding readings without the network, the 

 balanced-terminal capacity C\, and the grounded capacity unbalance 

 of the given pair of terminals are:^ 



a = 2(c"- Co'). 



G2 - Gi = 2 (C - Co). 



'' See appendix, section 5. 



