104 



METHODS OF COMMUNICATION FOR FOREST PROTECTION 



Branch line being made at the end of the rural line circuit, thus eliminating the 

 necessity of stringing an additional wire parallel to the rural line telephone circuit. 

 By the use of the phantom circuit a direct line is obtained to the exchange or town 

 where the rural line terminates without interfering with subscribers on the latter. The 

 circuit is so arranged that the grounded Forestry Branch line may be cut on the 

 metallic line direct through the 47-A repeating coil in an emergency. It is also 



To 



Co// 



Fig. 57 Phantom circuit 



arranged so that, should any of the ranchers desire to talk to one of the stations on the 

 Forestry Branch grounded line beyond the point where the rural line terminates, by 

 calling the station at the end of this line the switch at that point may be thrown and 

 direct connection had. This phantom circuit can only be built up where the metallic 

 line does not parallel any electric-light, power, high-tension, or railway wires. 



5 CONNECTION OF GROUNDED TO METALLIC CIRCUIT 



The necessity for making this type of connection frequently arises where the 

 Forestry Branch lines are joined to private or provincial lines near forest reserve 

 boundaries or at ranger stations, in order to give through service from points in the 

 reserve to points outside. It sometimes arises, also, when Forestry Branch metallic 

 circuits are constructed in order to eliminate inductive disturbances from power lines 

 or other circuits in their vicinity. 



A method of installing a switching station where a grounded Irne may be cut 

 through to a metallic line with a 47-A repeating coil in circuit is shown in Fig. 59. 



Equipment necessary: One 47-A repeating coil, two double-pole, double-throw, 

 baby knife-switches, and one telephone set. This method is used where connection is 

 necessary with some commercial toll line, one telephone being used on the commercial 

 line and the other on the Forestry Branch line. If a subscriber of the commercial 

 telephone company, or provincial line, is using the toll station, the call on the Forestry 



