wirelp:ss tp:leoraphy. 2()3 



Remarkable as these results are, however, tliej^ have been almost 

 totally overshadowed bV those w'ireless telegraph systems in which 

 electric waves, or ether Waves, are utilized, and of which the Marconi 

 wireless telegraph S3^stem is the best known. It is of this latter sys- 

 tem, as representing-, so far as the writer is aware, the most advanced 

 development of this art, that the present article will briefly treat. Tt 

 would obviously be far beyond the scope of a necessarily limited 

 account to deal with all the wireless telegraph inventions tliat have 

 been announced witliin the past few years. 



A\'luMi, in 1804:, Clerk-Maxwell, who Avas, perhai)s, tlie most noted 

 mathematician of his day, made announcement of his celel)rated elec- 

 tromagnetic theory of light, which theory involved the existence of 

 electric waves in free space, many of the prominent physicists of the 

 time set themselves the task of demonstrating l)y experiment the truth 

 of this theory. It was not, however, until 1887 that the actual exist- 

 ence of electric waves in free space was demonstrated, the great 

 honor of this accomplishment falling to Prof. H, Hertz, after whom 

 such electric waves are now almost generally termed '"'' Hertzian" 

 waves. The old popular idea of electricity hardl}^ conceived it as 

 existing outside of a wire or other metallic conductor. The air was 

 an insulator, and how, therefore, could electricity exist apart from a 

 wire! Maxwell overturned this view.j and told us that just as under 

 the undulatory theory of light that which we call light is a result of 

 ether vibration, so also is electricit}^ a resiilt of ether vibration, and 

 that in so far as light and electricity differ it is onh" a question of 

 the rate of vibration of the ether, those undulations of tlie ether 

 which the eye recognizes as light occurring at a rate varying from 

 4UO,0(H),000,00(),000 to 700,000,000,000,000 per second, while the fre- 

 quency of the electric undulations of the ether vary from a few hun- 

 dreds or thousands to 200,00(»,000,0(X),0(>() per second. 

 ' According to the undulatory theory of light, the undidations of the 

 ether, of the frequency just mentioned, are set up by any source of 

 light. Similarly, according to Maxwell's theory, undulations are set 

 up in the ether by any source of electric oscillations — analogously, for 

 example, as waves are set up in the atmosphere b}- a source of sound. 

 Also, as those ether waves which correspond in freqmMicy to light 

 afiect an organ of sight when they fall upon it, and as sound waves 

 aft'ect an organ of hearing when the}- fall upon it, so, it was reasoned, 

 should the electric waves of the ether affect a suitable electric ''eye," 

 or receiver, when they fall upon it. 



The manner in which Professor Plertz proceeded to show the exist- 

 ence of electric waves in free space was, briefly, as follows: It was 

 already known that electric oscillations could be set up in a well- 

 insulated Avire or conductor; in fact, that the discharge of the I^eyden 

 jar is made up of a series of electric oscillations, as had been shown 



