1871J 



Electricity, 



117 



occur to the mystified authorities at Versailles that, by means of them, 

 telegraphic communications may be sent, and even received, without any of 

 the paraphernalia of an ordinary telegraph office, provided some of the latter 

 are at the other extremity of the line-wire. 



If the French telegraphists have outwitted the Germans at Versailles, the 

 latter have retaliated at Meudon, where a complete underground electric 

 telegraph was discovered in one of the cellars. For days the unconscious 

 French were sending messages, which were " tapped " by the Prussians to no 

 great purpose, however, as they were generally in cypher. 



Varley's Singing Telegraph. — Mr. C. F. Varley, C.E., of Fleetwood House, 

 Beckenham, Kent, has just invented some telegraphic apparatus, whereby two, 

 three, or more messages can be sent on one line wire at the same time, and 

 without interfering with each other. This invention, therefore, is likely to 

 prove of considerable value, since it will so largely increase the transmitting 

 power of line wires at present overcrowded with work, and will save the cost 

 of hanging additional wires between London, Liverpool, Manchester, and other 

 large centres of industry. Another remarkable feature of the invention is, that 

 the instruments sing, or rather, " hum " their messages. The Morse alphabet 

 is used ; a loud, long hum is given for a dash, a quieter and a shorter hum is 

 given for a dot. When one of the instruments is at work it sounds as if a big 

 bee were teaching a little bee to exercise its voice, because, as a general rule, 

 the loud and softer sounds are given alternately. The sounds are caused by 

 the vibrations of a thick iron wire, the instrument being something like a violin, 

 five feet long, with one thick string. The first instruments, made for experi- 

 mental purposes, worked well ; the writer read off messages by them, which 

 Mr. Varley sent from another part of the house, through a hundred miles of 

 wire, of the electrical resistance of that ordinarily used on land for telegraphic 

 purposes. 



By the new apparatus, waves are superimposed upon the currents ordinarily 

 used in working a Morse circuit, and the receiving instruments respond to the 

 action of these small waves. Suppose a long rope, with a weight at each end, 

 were passed near the ends over two pulleys ; signals might be transmitted by 

 pulling the rope at either end, and lifting the opposite weights up and down ; 

 if now, at the same time, vibrations or waves were set up in the rope by 

 striking it with a stick, and an observer could read off messages sent by these 

 small undulations, we should have an effect analogous to the new system of 

 telegraphing. 



Let a b, Fig. 20, be the line wire ; Mr. Varley attaches a condenser, d, to it ; 

 the other side of the condenser is attached to the sending apparatus, which 



Fig. 20. 



Fig. 21. 



charges and discharges the condenser with great rapidity ; consequently, these 

 impulses add to and take from the line a number of small waves, without 

 affecting the mean magnetising power of the ordinary Morse current. The 

 diagram shows how the apparatus is connected for receiving messages. The 

 " key " or commutator, e m h, when not in use for sending messages, keeps 

 the condenser, d, in contact with the receiving instrument, k, through the 



