10 L. Schwendler— On the General Theory of Duplex Telegraphy [No 1, 



Considering that 



K" i + I" + p" 

 K'~~i + l' + p 



i 



P = 



i + V + p 



and 



K " T J, > J. » X & + P') V" + ^ 



7 = X ^ +p + J 



we have 



,_ £ » + I" + p" V t/ y/V , 



x ~ e"' i B! ,/«'' 



put 



i +l" + p" 

 i 



= J 



T .,. n , 0' + PO V " + P*) 7 



-£ + P + P + : = -* 



and 



Ii 



V 77 



f 



.-. D' = sJ\' v'. — 8K' 



Z> 2 ' = Sef 4 8 B' 



T 

 D' = sv'— SA' 



Now keeping 5, J", A', and v' constant, D x ' becomes smallest for any 

 given S-ST' the larger 1// is selected ; while _D 3 ' becomes smallest for any given 



T 



8 A' the smaller — is selected, and D 2 ' becomes smallest the larger B' is 



chosen. 



i// = B' „/— has a maximum for a' = b' ; 



Now 



" b 



for B' = V + a! + <#' = V + y, and putting y = b' f we have 



xj/' = (1 -f- O \/ ft ' 6' which, for a' -f- &', and #' constant, has 



