110 THE ELECTRIC TELEGRAPH. 



circuit, including the electro-magnet of the spacing-appa- 

 ratus. 



Cj and c n are two switches for altering the position of the 

 apparatus to suit the requirements of the service. The 

 former the line switch is for directing the line, on one 

 side, for translation, and on the other, for ordinary reception 

 from, and transmission of signals to the station on the side 

 of the switch ; the latter, or key switch, is for arranging the 

 board for sending or receiving. 



When the apparatus is connected up for translation, which 

 is done by simply turning over the arms of the switches Cj and 

 c n to their contacts, 2, a positive current arriving by the line 

 L on the left-hand side, has to pass through the longer coil 1 of 

 the galvanoscope, G, of apparatus No. 1 ; by c x to the point 2, 

 and from this direct by the leading wire, across to apparatus 

 No. 2, where it passes passively over the printing beam 3 of 

 the Morse instrument, M X , by the contact screw 1, to the 

 beam of the spacing-apparatus, over which it also passes 

 passively to the reposing contact 2 ; from this, back again to 

 apparatus No. 1, where it traverses in succession the coils of 

 the two relays, and, finally, by wire w 2t passes through the 

 shorter coil 2 of the galvanoscope, and goes to earth at the 

 plate marked " earth." 



The coils of the relays ^ and R 2 being connected up so 

 that the current circulates in reverse directions in them, the 

 positive current, which we are considering, can only deflect 

 the armature of R 2 , which closes that side of the local circuit 

 containing both Morse and spacing-apparatus, the beams of 

 both which will be depressed. 



The beam of the Morse, M, being connected by means of 

 the line-switch tf I? through G 1? with the down line L 1 ; and 

 the contact-point 2 on which the beam of the Morse strikes, 

 being connected by wire, w t with the copper pole of the 

 battery c, E, a positive current passes from c, E (w, 2 M, 3, 

 c' If 2, G-'J to L!. 



During this time, the armature of the spacing-apparatus, 

 although drawn down, has sent no current into the line, 

 because its circuit is interrupted by the depression of the 



