TELEGRAPHING WITHOUT WIRES

Ashburton Guardian, Volume V, Issue 1534, 16 April 1887, Page 2

TELEGRAPHING WITHOUT WIRES

— ~ — • — I i (" Engineering.") 1 Professor Dolbear, the well-known American elec'rlclan, has succeeded In 1 telegraphing without wires by causing a series of electrical discharges to pasi into the earih wi hint discharging into it the other terminal of the battery or indaotion apparatus used. Suppose the positive pole of an induction coil be "earthed" one hundred times a second, then the ground th.9re would have its potential raised one hundred times per second. At a distant point let the negative pole cf a similar coil bo earthed one hundred times a second ; It follows that between these two points there will be a greater difference of potential than at surrounding points, and a current will fljw between them one hnadred times a second. The telephone is used t> interpret these current*, which are interrupted by a Morse key, arid the humming sound caused m the telephone by. the vibratory current is broken into long and short s'gnals. or dots and daabes. The plan is adopted for telegraphing between vessels at sea, and indeed 1b similar to that recently tried by Professor Graham Bell* m Boston harbor. Professor Dolbear desorlbed his plan m 1883, but it can hardly be called novel.