AUTOMATIC PRINTING EQUIPMENT 



415 



exceed one third of the normal signal amplitude. The presence of a 

 proportionate amount of interference in the received signals in ordinary 

 cable code operation would cause the recorder record to be so mutilated 

 as to render it entirely illegible. 



A detailed description of the operation of the synchronous vibrating 

 relay is given in the appendix. 



Refinement 



The extreme speed at which the apparatus must operate to utilize 

 the entire capacity of a loaded cable precludes making any adjustments 

 while in operation and the importance of maintaining uninterrupted 

 service for long periods demands that the apparatus shall be absolutely 

 reliable in its operation and as free as possible from any variation in 

 adjustments which would require occasional correction. This degree 

 of reliability is secured through a refinement in mechanical and 

 electrical design and a precision in construction which might be 

 considered uneconomical for ordinary land line operation. The extra 

 expense incurred in the design and construction of such highly refined 

 apparatus is well justified by the resultant large increase in traffic 

 capacity of the cable and the small cost of even the most refined 

 apparatus relative to that of the cable on which it is used. 



A general idea of the type of apparatus and construction used can 

 be gained from one of the terminal distributors which is illustrated in 

 Fig. 4. The greatest permissible variation in the phase relation 



VIBRATING RELAY StGMElNTS RECEIVING SEGMENTS 



I /" local printer segments 



niRFCT CURRENT MOTOR 



PHONIC WHEEI MOTOR 



CORRECTING 

 \ SEGMENTS 



SENDING 

 SEGMENTS 



TRANSMITTER 

 LOCAL SEGMENTS 



TIMING CAM 

 CLUTCH 



DIAL FOR AD- 

 JUSTING PHASE 

 POSITION OF RECEIV- 

 ING BRUSHES 



Fig. 4 



