CHAP. IV. J 



ELECTRIC TELEGRAPHY. 



51)3 



When a message is being punched, each depression of a key 

 besides punching the hole, also mechanically moves the ribbon forward 

 the exact space for receiving the 

 next perforation, so that by succes- 

 sive depression of the respective 

 punches the holes are cut in the 

 paper ribbon in the necessary se- 

 quences to represent letters and 

 groups of letters to form words 

 and sentences. The message is ~ 

 thus written and prepared away 

 from the wire. The second part, 

 or " transmitter," is the apparatus 

 which automatically sends into the 

 line wire the sequence of currents, 

 as prepared by the "perforator." 

 The perforated ribbon paper strip 

 is caused to advance step by step 

 through the machine by the sue- ^ 

 cessive grip of an oscillating cradle, 

 adjusted so as to advance the paper 

 at each oscillation a distance exactly ^ 

 corresponding to the spacing of the 

 holes by the " perforator," so that by 

 the action of a rising pin, elevated 

 and depressed alternately at each C 

 to-and-fro motion of the roeking- 

 frame, the message ribbon is auto- 

 matically and mechanically impelled ^ 

 forward. Two other spring " con- 

 tact " pins representing respectively 

 the contact with the positive and 

 negative currents are actuated by 

 the same mechanical movement. 

 When therefore the perforated 

 paper ribbon is carried automati- 

 cally forward step by step in rapid succession by the action of the 

 central pin, if a "current-passing" perforation in ths paper ribbon is 



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