154 Telephone Systems of the Continent of Europe 



nected through j 2 ; consequently, the talking is done by translation, 

 although the subscribers' lines are double. At Paris the trans- 

 lator primary could be dispensed with, the secondary replaced by 

 a pair of balanced resistances on Jacob's plan, and the talking 

 done direct through the jack j 1 ; but this would not be so at 

 single-wire centres. 



Of the three systems the Cailho seems to be preferred, as being 

 the most trustworthy under adverse influences. Of course, both 

 the Cailho and Picard are far simpler than the Van Rysselberghe, 

 but, on the other hand, they furnish only one telegraphic circuit 

 from each telephone trunk, while Van Rysselberghe makes two. 



In the Belgian section the phonic call designed by M. Sieur 

 has been described (fig. 20), and it is pointed out that its use 

 involves much waste of chemicals, since 

 the battery is permanently short-circuited 

 through the diaphragm and lever contact. 

 M. Picard, by a simple modification of the 

 connections, interposes a resistance in the 

 circuit and so saves the batteries to a con- 

 siderable extent. His arrangement is shown 

 in fig. 40, in which A is a pivoted lever, with 

 adjustable weights ww, resting normally in 

 contact with the diaphragm D. M is an 

 electro-magnet with coils of equal resistance, 

 joined in parallel, which oppose each other 

 in respect to the armature ; and v is a battery, the current from 

 which splits between the diaphragm, lever and coil c, and coil c 1 . 

 Whilst the diaphragm remains quiescent the two opposing circuits 

 are of equal resistance, and no effect is produced on the armature ; 

 when it vibrates, the intimacy of the contact between it and the 

 lever is destroyed, circuit c becomes of greater resistance than c 1 , 

 and the battery, acting through the latter, actuates the armature, 

 which is generally arranged to release a shutter. At night the 

 shutter closes another local circuit and rings a bell. 



An excellent plan for the speedy determination of disputes and 

 complaints is in operation in Paris. Apart in a small room, at 

 a switch-board provided with 20 indicators, sits an inspector. To- 

 the switch-board are brought two lines from each of the ten switch- 



FlG. 



