Switzerland 



393 



inserted and the test line and battery joined (fig. 134), J is excited 

 and draws o back to its upright position, the aluminium plate P 

 then falling and covering the number. This plan relieves the 

 operator of the work of restoring shutters after use ; it also enables 

 the shutters to be removed out of reach, thus affording more 

 space for the jacks. Once adjusted, the drops act well, probably 

 better than ordinary ones, which are subjected to careless and 

 sometimes rough handling by 

 the operators. Figs. 136 and 

 I36A represent front and end 

 plans of the table. The indi- 

 cators are mounted above in 

 sections of 120 lines, having 

 below them a strip of fifteen 

 ring- off indicators for each 

 operator. Then come the 

 repeat jacks in sets of 100, 

 each operator having 1,800 

 before her ; and below, the local 

 jacks. Fig. 137 gives a good 

 idea of the general appearance 

 of the table. Owing to the 

 length of cord necessary to 

 reach over so many jacks, the 

 shelf supporting the keys and 

 plugs is one meter above the 

 floor, and the operators' seats 

 have consequently to be very 

 high 80 centimeters. Fig. 138 

 shows the connections of an 

 operator's apparatus. The left 

 and right keys are for ringing in either direction, the middle one 

 for cutting in the operator's phone. The ring-off indicators, like 

 the calling ones, are in parallel between the cord conductors, so 

 that when a connection is on there are three indicators in deriva- 

 tion across the circuit. But when a ring-off comes, only the 

 proper drop falls, as the two others are held up by the test current 

 circulating through their restoring coils. The ring-off drops are 



FIG. 136 A 



