Typewriting Eight Telegrams Over 



a Single Wire 



WHEN the possibilities of sending 

 messages over a wire by elec- 

 tricity were first realized, soon 

 after Morse demonstrated the first tele- 

 graph, the limitations in the message- 

 carrying ability of a plain circuit were 

 encountered. The ordinary good oper- 

 ator could send only about one complete 

 message per minute, and to do this he 

 required the full use of a wire connect- 

 ing him with the receiver. Each line 

 was thus limited to about four hundred 

 messages per business day, and it be- 

 came clear that extremely high rates 

 would have to be charged for messages 

 over expensive long distance wires. The 

 greatest cost of the telegraph system 

 was due to the erection and maintenance 

 of the lines, and therefore the best way 

 to make lower charges possible appeared 

 to be to increase the number of mes- 

 sages which could be handled on each 

 wire. 



The first step toward solving the prob- 

 lem of message limitation came with the 

 duplex telegraph, which made it possible 

 for four Morse operators to use a single 

 wire at the same time. In this system 

 two streams of messages pass over the 

 wire simultaneously, in opposite direc- 

 tions, so that the capacity is doubled. 

 The next step was the quadruplex, in 

 which four messages are sent simul- 



taneously, two in each direction, over 

 the same wire. In this system one line 

 carries about sixteen hundred messages 

 per day, and large saving, as compared 

 to plain or simplex single-message tele- 

 graphing, results. The duplex and cjuad- 

 ruplex are very greatly used today, and 

 the latter is not easy to keep in full op- 

 eration during rainy weather. An octu- 

 plex system was devised, but has not 

 been found practical. 



Since the hand-telegraph systems are 

 limited in message capacity by the 

 speed of the Morse operator, automatic 

 receivers and transmitters were de- 

 vised to speed up the impulses passing 

 over the line. In the Wheatstone sys- 

 tem, which is perhaps the most success- 

 ful of the plain automatic telegraphs, it 

 is possible to send three hundred or 

 four hundred words per minute over one 

 wire, thus increasing the normal capac-- 

 ity some ten or twelve times. In this 

 system the messages are first pimched 

 into special tapes by perforating oper- 

 ators. The tapes which are simultane- 

 ously punched out by ten perforators, 

 will usually keep one wire in full oper- 

 ation. At the receiving station the mes- 

 sages are printed in dots and dashes on 

 a second tape ; this is divided into suit- 

 able lengths and distributed amongst a 

 number of transcribing operators who 



This remarkable telegraph system has been in operation over the lines shown for many 

 months, and has resulted in the saving of much time and money to the company, and 



eventually to the senders 



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