206 



Commendatore G. Marconi 



[June 2, 



stand but incompletely the true fundamental principles concerning 

 the manner of propagation of the waves on which wireless telegraph 

 transmission is based. For example, in the early days of wireless 

 telegraphy it was generally believed that the curvature of the earth 

 would constitute an insurmountable obstacle to the transmission of 

 electric waves between widely separated points. For a considerable 

 time not sufficient account was taken of the probable effect of the 

 earth connection, especially in regard to the transmission of oscilla- 

 tions over lonsf distances. 



Fig. 12. 



Physicists seemed to consider for a long time that wireless tele- 

 graphy was solely dependent on the effects of free Hertzian radiation 

 through space, and it was years before the probable effect of the con- 

 ductivity of the earth was considered and discussed. 



Lord Rayleigh, in referring to transatlantic radiotelegraphy, stated 

 in a paper, read before the Royal Society in May 190o, that the re- 

 sults which I had obtained in signaUing across the Atlantic suggested 

 " a more decided bending or diffraction of the waves round the pro- 

 tuberant earth than had been expected," and further said that it im- 

 parted a great interest to the theoretical problem.* Pi'ofessor 

 Fleming, in his book on electric wave telegraphy, gives diagrams 

 showing what may be taken to be a diagrammatic representation of 

 the detachment of semi-loops of electric strain from a simple vertical 

 wire (Fig. 13). 



As will be seen, these waves do not propagate in the same manner 

 as does free radiation from a classical Hertzian oscillator, but instead 

 glide along the surface of the earth. 



Proc. Roy. Soc, vol. Ixxii., p. 40. 



