156 METHODS OF COMMUNICATION FOR FOREST PROTECTION 



If this does not reveal the cause of trouble, unfasten the receiver cord from the 

 terminals in the telephone set and, while holding the receiver to the ear, touch the 

 two terminals of the receiver cord to the terminals of one of the dry batteries. If you 

 can hear a click when the cord is connected thus, the receiver is all right and there 

 must be some fault in the wiring. If you do not hear a click, it is probable that the 

 receiver winding or the cord is broken. 



If you cannot hear at all, the fault is due to a broken wire in receiver or cord. 



Trouble No. 10, Neither you nor others can hear distinctly. 



Cause. -Poor joints or connections, batteries or grounds. 



Remedy. The trouble is probably due to some loose connection or poor or corroded 

 joint in the wiring at the telephone station or out on the line, exhausted batteries or 

 poor grounds or a loose lightning-rod touching the line. 



Trouble No. II, The stations at the terminals of the lines have increasing difficulty 

 in ringing or hearing each other plainly. 



Cause. Too many stations on line; too long a line for size of wire used; ground 

 rods in too dry soil; corroded splices; poor joints; excessive line leakage through 

 contact with trees, poles, or foliage. 



Remedy. Fix up the entire line. If this improves the talking but not the ring- 

 ing, see that all the telephones on the line have 2,500-ohm ringers. See that the 

 generator crank-shaft comes back into place after calling a station on the line. If 

 this does not make the ringing satisfactory, cut off some of the stations or divide 

 the line into sections, or rebuild the main line, using heavier wire. In extreme cases 

 it may be necessary to build' a copper, metallic circuit. The fault may be due to 

 similar conditions or poor maintenance on a foreign telephone line or switchboard 

 to which the Forestry Branch line is connected. 



4 CROSS-TALK 



Cross-talk occurs when two grounded lines are strung on the same poles. This 

 interference with conversation is reduced as far as possible on a grounded line by 

 good grounds at all subscribers' stations. Separate ground rods should be used for 

 separate lines. If it is desired' to eliminate cross-talk, the circuit must be made 

 metallic and the standard method of transposition followed. By making one of the 

 two lines metallic, cross-talk is eliminated on the metallic line but may still cause 

 trouble on the grounded line. Cross-talk will not generally arise unless the Forestry 

 Branch line parallels a second grounded or metallic line, closer than 30 ft., for a 

 distance of more than a quarter of a mile. 



5 STATIC ELECTRICITY 



A great deal of inconvenience may be caused by static electricity. There may be 

 no trouble in the morning, but toward noon a frying noise is apparent and! in the 

 evening it is impossible to carry on a conversation. Trouble from static electricity 

 is usually greater at high altitudes than at low. 



One method of removing static electricity from a linens by the use of a lavite 

 coil with a resistance of 48,000 ohms. This coil should be installed along the lino 

 at intervals of from 3 to 10 miles, and attached to a grounded line as shown in Fig. 51. 

 In a metallic line two coils should be attached, one to each wire. The same ground 

 may be used for both coils. The coil should be inclosed in a small weather-proof 

 box. 



Another method of draining static electricity is by the installation of vacuum 

 lightning-protectors. These protectors should be installed in the same manner as 

 the lavite coil, except that the fuse may be omitted. 



It is sometimes necessary to make a study of static conditions, as the distance 

 between coils is not the same in all cases. Before doing so the district inspector 

 should be asked for definite instructions. 



