634 



BELL SYSTEM TECHNICAL JOURNAL 



A feature worthy of note is that with this machine typing always 

 occurs at the same point introducing a problem in connection with 

 platen wear. If the platen were fed by the usual ratchet in, say, 36 

 steps per revolution, there would be heavy wear concentrated at these 

 36 points and the platen would require frequent replacement to pre- 



Fig. 8— No. 14 teletypewriter. 



serve good printing. To avoid this, the platen is fed through differ- 

 ential gearing so that on a second revolution the typing comes in a 

 different spot from that of the first revolution; thus the wear is uni- 

 formly distributed over the entire circumference. 



One carbon copy can be made by leading tapes through the machine 

 from two rolls of record paper and one roll of carbon paper. Two 

 carbon copies can be made in a similar way if desired. 



