174 THE ELECTRIC TELEGRAPH. 



K l , 1, u, contact peg, 2) to line, &c. ; and from z (through 1, 

 K) to earth. 



In case it is wished that the Morse apparatus print the 

 message, for the sake of control the contact peg of u is not 

 put into the hole. On pressing down the lever K, the current 

 of L B passes from c (2, K) to earth, and from z (1, K 1 , 1 of u, 

 coils of D, 1, 2, u 2) to line, &c. The other lever K 1 being 

 pressed down, whilst K is at rest on the back contact, the 

 positive current goes from c (2, K 1 , 1 of u, coils of D, 1 and 

 2, u 2) to line ; and the negative current from z (1, K) to 

 earth. 



In this way the station apparatus M M l prints the message 

 as well as that of the receiving station. 



The apparatus is ready for the reception of messages when 

 the contact stopper is out of u. 



The currents arising from the line have to pass u 2, coils D, 2, 

 1, u 1, K J, bar 1, K, to earth, and back to the sending station. 

 The poles of the electro-magnet D become magnetic, and 

 according to the direction of the current in the line attract 

 one or other of the keepers, E, F. 



When a positive current arrives, F is attracted and E 

 repelled. The result is that the local circuit of M 1 is 

 closed ; the current of the local battery B moves in the 

 circuit c, cores of p, F, coils of M 1 z. The beam of M 1 

 is attracted, and the style impresses the paper with marks 

 on the lower side. When the sending station reverses the 

 direction of the current by pressing down the other lever of 

 his key, the keeper E of the relay is attracted, and F 

 repelled. By this the current of M 1 is interrupted, and 

 that of M established ; the local current of B, now circulates 

 in c, soft iron cores of D, E, coils of M, z, by which the beam 

 of M is acted upon, and the style marks the paper on the 

 upper side. 



The elementary signs, dot and dash, in each of the rows 

 marked by the styles, give four elements for the composition 

 of an alphabetical code. The consequence is that fewer 

 signals are required for the formation of letters, &c., than in 

 Morse's code. 



