Signalling through space without wires : being a description of the work of Hertz & his successors . Fia. 41 (Fig. 7 of Specification 29,069/97).—Diagram of connections ata protected Coherer Station with Syntonic Radiator and Collector. relay, for sound signals and as an automatic tapper for thecoherer, I obtain an apparatus which exactly answers everyelectric wave by a short ring, and by rhythmical strokes ifelectric vibrations be excited continuously. On connecting an electro-magnetic recorder in parallelwith the bell, tracing a straight line along the paper bandwhich is moved by a 12-hour c
Signalling through space without wires : being a description of the work of Hertz & his successors . Fia. 41 (Fig. 7 of Specification 29,069/97).—Diagram of connections ata protected Coherer Station with Syntonic Radiator and Collector. relay, for sound signals and as an automatic tapper for thecoherer, I obtain an apparatus which exactly answers everyelectric wave by a short ring, and by rhythmical strokes ifelectric vibrations be excited continuously. On connecting an electro-magnetic recorder in parallelwith the bell, tracing a straight line along the paper bandwhich is moved by a 12-hour clockwork cylinder, I obtain aninstrument registering by a cross line on the moving band 62 SIGNALLING WITHOUT WIRES. every electric wave that reaches the coherer from across theatmosphere. Such an apparatus was placed at the Meteoro-logical Observatory at St. Petersburg in July, 1895, one ofthe electrodes of the coherer being connected by an insulatedwire with an ordinary lightning conductor, the other electrodeof the tube-coherer being connected with the Fia. 42 (Fig. 2 on p. 235 of The Electrician, Vol. XL.).—Method ofautomatic tapping back by relay-current employed for telegraphy byProf. Popoff in 1895. Prof. Popoff then goes on to say that his apparatus workswell as a lightning recorder, and that he hopes it can be usedfor signalling to great distances. He says:— I can detect waves at the distance of one kilometre if Iemploy as sender a Hertz vibrator with 30 centimetre spheres,and if I use the ordinary Siemens relay; but with a Bjerknesvibrator 90 centimetres diameter, and a more sensitive relay,I reach five kilometres of good working. Thus it is plain that Prof. Popoff employed the elevatedwire as receiver in 1895, but did not employ it as sender. TELEGRAPHIC APPLICATIONS. 63 In 1897 Prof. Slaby, of Berlin, published (in German) abook called Spark Telegraphy, in which he described hissuccess in signalling from 3 to 13 miles across land. Fromthis book we tak
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