WIRELESS TRANSMISSION OF ENERGY THOMSON. 



245 



stressed the ether in one and the other sense, so that an electrical 

 wave was radiated in certain directions from the oscillator. It was 

 found that these waves could be refracted, reflected, and polarized, 

 and, in general, dealt with as extremely coarse light or heat waves. 

 We shall refer to these, however, farther on. The general result, 

 however, of the Hertzian experiments was to connect electrical waves 

 in the ether surrounding the apparatus Avith the light and heat 

 waves and prove the identity of the two kinds of radiation, the 

 differences being only those of wave length or pitch. 



Since the Hertzian waves were sent out from the Hertzian oscil- 

 lator in substantially straight lines, and since in the early days of 

 wireless telegraphy it was common to regard wireless waves as of 

 the same nature or as almost identical with Hertzian waves, the 

 fact that the wireless waves were found to follow the curvature 

 or the earth became 



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a difficulty to be ex- 

 plained. Speaking 

 for myself, I have 

 never found the diffi- 

 culty to exist. There 

 is really no reason 

 why the waves should 

 not follow the curva- 

 ture of the earth, as 

 it will be one of my 

 purposes to show. We 

 will, however, ap- 

 proach the conditions 

 of wireless somewhat 

 gradually. 



We will first consider an ordinary wire transmission of the sim- 

 plest type. Let us assume a line of wire, as in figTire 3, insulated 

 and connected to one terminal of the battery while the other terminal 

 is earthed or grounded. A simple telegraph system on open circuit 

 would represent this arrangement. The only effect is that the battery 

 supplies a small charge to the line, producing a potential difference 

 between the insulated line and the earth, assuming, of course, that 

 there is no leakage of any kind to disturb the conditions. As soon 

 as the charge is established in the line at the full potential of the 

 battery, which, in ordinary cases, would take place within a very 

 small fraction of a second, a steady or static condition is reached, 

 which might be indicated by electrostatic stress lines drawn from the 

 wire to the ground, as illustrated in figure 3 by the fine dotted lines 

 connecting the horizontal line to the ground surface below. If the 

 wire be viewed on end (fig. 4), we must represent these stress lines 



