462 



Mr. L. Schwendler on the General Theory 



the difference of force by which single and duplex signals are 

 produced is equal in magnitude and sign to the force by which 

 balance is disturbed; further, that it is perfectly immaterial 

 whether the same or opposite poles of the signalling-batteries are 

 put to earth. For reasons already explained, I prefer to use the 

 negative poles of the signalling- batteries to earth in both sta- 

 tions ; and this alternative we will suppose is adopted. 

 Thus we have 



p' =A!m'-Wn l > 



P'=-(flW + »'«*') 



Q'= {A.'-%,<)m'-{B' + W)n'. 



If we now substitute for A', B', &', ffl their values, we get 



E' 



'— — A' 



^77 f* X > 



and 



^ted^ji 



N" ^ ' N' 

 the sign of p l being contained in A', and where 



W =f(b' + d' + a' + h' + c') + {V + d f ) (a' + h' + c f ), 

 N" =f{W + d" + a" + W + c") + {b" + d") {a" + h" + c"), 



P 



+ * + / 



A' = {if + d f )m' - (a' + h' + d)n', 



\ ! = m f + 



f 



b' + d'+f 

 Thus the general expressions for the two functions D and S are 



P 



E' 



D'= £-. = — • 



N" 



E" N'(b" + d") fM f \' 

 E' 



° —p w 



and 



A" 



^ - pr - E' N" (# + «*') n"\'" 



E" 

 S"=»" = — A" 



for station I., 



> for station II. 



