4 L. Schwendler — On the General TJieory of Duplex Telegraphy . [No. 1, 



p' = -f A' m' 4- B' n' 



B' = + %• m ' 



Q'= (+ A' + a')W + B' ri 



2nd. Opposite poles of the two line batteries are connected to earth 

 in the two stations : 



p' = + A' m' 4- B' n' 

 B' = ± %' m' 



Q'=(± A' ±<&')m' + B'n' 

 Subtracting in either case P' from Q', we get 



Q' — B' = S' = f 

 Or, on account of having fulfilled the key equation f=w-\-B i the 

 difference of the forces which produce single and duplex signals is equal in 

 sign and magnitude to the force by which balance is disturbed. Further it 

 is, also for the compensation method, quite immaterial whether the same or 

 opposite poles of the two line batteries are connected to earth. As pointed 

 out, it is preferable to connect the same poles, i. e., the negative poles of the 

 line batteries to earth. 



Assuming this case we have : 



<p' = A' m' — B' n' 

 B'= — %! m' 

 Q' = [A! — &') m! — B' n' 

 Substituting now for A', B', and &' their values, and remembering that 



- I approximately. 

 n' = r'\/b' ) 



we get the following general expressions for the two functions B and 8 : 

 A' 



8' =e'q 



B' K' 

 e' K" A' } ^ or station I. 



and 



A" 



8" = e" q" T 



* B' K" 



j£> a» > for Station II, 



fX 



where A,= B\/a s — K A v \Zb 

 B = a + b + d 



