HISTORY AND PROGRESS. 



101 



through o 1 , u, K 1 , c 1 , and coils of R 1 , c 1 , u, 2, earth, &c. The 

 cross-commutators are put between the back contacts of the 

 keys and bars of the commutator u, in order to enable the 

 operator to invert the coils of the relays, in case the residuary 



irth\ 



Fig. 53. 



magnetism in the soft iron cores, from continued currents in 

 one direction, should interfere with their delicacy. 



The currents transmitted from the station towards L 1 , by 

 pressing down the key K 1 , take the direction from L B, copper 

 pole c, front contact and lever of key, first bar of commutator 

 u, G 1 , and L 1 . The operations with apparatus 2 and L 2 are 

 similar. 



When the contact peg is put in one of the holes, 3 or 4, 

 the apparatus on the opposite side to that in which the peg 



put in, is ready for participating in any messages that 



