DEVELOPMENTS IN TELEPHONY AND TELEGEAPHY JEWETT. 501 



special windings and special arrangements of contact springs as- 

 sembled from standard parts. 



Another striking change in telephone apparatus has been the sub- 

 stitution of metal for wood, particularly in connection with the 

 housing of substation apparatus. "VVliere formerly the subscriber's 

 set and the apparatus box were made from wood, the standard 

 practice now is to employ drawn-steel housings, properly japanned. 



2. WIRE TELEGRAPHY. 

 LAND SYSTEMS. 



Although the telegraph was the first of the electric intelligence 

 transmission systems in the field, progress in the art during the 20 

 years following 1885 was not as great as the progress in the telephone 

 field. Eecently, however, great activity has been shown in the mat- 

 ter of utilizing the telegi'aph-wire plant to better advantage. Not 

 only has the use of the superimposed telegraph been greatly extended 

 in the telephone plant, but there have also been striking developments 

 in the realm of printing and high-speed telegraph systems. 



The primary object of these developments has been economy in 

 the wire plant and in operating costs. As a result of what has been 

 accomplished it is probably an underestimation to state that one 

 telegraph circuit can now be made to carry as much traffic as four or 

 five circuits operated by liand-speed Morse. It should be noted in 

 passing that this statement is not intended to convey the idea that all 

 telegraph circuits should be so operated. 



Two radically different fundamental ideas have been developed in 

 the last decade, namely, the high-speed and the multiplex. In the 

 high-speed printing system the messages are first prepared on per- 

 forated tape by a number of operators, and these tapes when col- 

 lected are fed into a transmitting machine in sequence. This trans- 

 mitting machine converts the perforations in the tape into telegraph 

 signals, Avhich pass out over the line. At the receiving end the mes- 

 sages may be printed directly on a paper tape or they may be received 

 as perforations in a tape, which is later fed into a special tj^pewriter 

 designed to translate the perforations into Roman characters. 



In high-speed systems the printed tape at the receiving station is 

 gummed to the telegraph blanks. Thus the operations at the sending 

 station of bringing the perforated tapes to the high-speed trans- 

 mitter and at the receiving station of distributing the messages and 

 gumming the tapes are manual, and a natural development would 

 be toward performing these operations automatically or else elimi- 

 nating them altogether. 



