94 



THE ELECTRIC TELEGRAPH. 



the current passes direct from the z-pole of the battery to 

 the earth-plate and earth, and from the c-pole through the 

 line galvanoscope, line, key of opposite station, and relay, to 

 earth. The deflection of the relay-tongue, from contact 1 



Line 



Fig. 48. 



to contact 2, closes the local circuit, and the armature of the 

 receiving instrument works in conformity with the motions of 

 the. key at the sending station. 



Another method of connecting up the same instrument 

 for two stations is shown in Fig. 49. In this method the 

 lever of the key is in permanent contact with earth. The 

 c-pole of the battery is connected with the front contact of 

 the key, and the z-pole with the point of junction between 

 the galvanoscope and relay, the latter being inserted between 

 the galvanoscope and back contact of K. The local circuit is 

 arranged as before. 



A current arriving by the line while the key is at rest 

 passes through the galvanoscope, coils of relay, back contact 

 and lever of key to earth. When the key is pressed down 

 on the contact 1, the c-pole of the battery is put to earth 



