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It's just It what we call Electricity, but the magic the manifestations the Hertzian waves are all revealed by this. The coherer, we call it." He picked up a glass tube not much thicker than a thermometer, in which, almost touching, were two tiny silver plugs, and between them an infinitesimal pinch of metallic dust. "That's all," he said, proudly, as though himself responsible for the wonder.
Chadwick, "we find that the problem in radio telephony is the same as that met with in ordinary wire telephony. That is to say, we are required to cause a distant metal disc to repeat every inflection of the transmitter. But in the case of radio telephony the result is to be obtained by Hertzian waves, instead of by a current passing through an insulated wire."
The idea of utilising such a very interesting phenomenon as an indicator in the study of the Hertzian waves seems to have occurred simultaneously to several physicists, among whom should be especially mentioned M. Ed. Branly himself, Sir Oliver Lodge, and MM. Le Royer and Van Beschem, and its use in laboratories rapidly became quite common.
The visitors, seeing plainly in the dark night, must have been able to see her by the vague luminosity of what for us is the dark. What would happen if I imprisoned her in an opaque receptacle? Would not such a receptacle arrest or set free the informing effluvia according to its nature? Practical physics has given us wireless telegraphy by means of the Hertzian vibrations of the ether.
To play the part, for example, with the Hertzian waves, which a mirror 1 millimetre square plays with regard to light, would require a colossal mirror which would attain the size of a myriametre square. The efforts of physicists have to-day, however, filled up, in great part, this interval, and from both banks at once they have laboured to build a bridge between the two domains.
Should the historian desire to give a conclusion to his labour and answer the question the reader would doubtless not fail to put to him, "To whom, in short, should the invention of wireless telegraphy more particularly be attributed?" he should certainly first give the name of Hertz, the genius who discovered the waves, then that of Marconi, who was the first to transmit signals by the use of Hertzian undulations, and should add those of the scholars who, like Morse, Popoff, Sir W. Preece, Lodge, and, above all, Branly, have devised the arrangements necessary for their transmission.
It was an article in an electrical journal describing the properties of the "Hertzian waves" that suggested to young Marconi the possibility of sending messages from one place to another without wires.
The term electric radiation was first employed by Hertz to designate waves emitted by a Leyden jar or oscillator system of an induction coil, but since that time these radiations have been known as Hertzian waves. These waves are the underlying principles in wireless telegraphy.
"The operator is getting his apparatus ready to signal to Williams," remarked Craig. "This is an apparatus called an ondometer. It tells you the direction and something of the magnitude of the Hertzian waves used in wireless." Five or ten minutes passed. Norton was getting ready to fly.
He used various substances in place of the carbon granules and showed that some of them will arrange themselves so as to allow the passage of a current under the influence of the spark setting up the Hertzian waves. Professor E. Branly, of the Catholic University of Paris, took up this work in 1890.
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