WIRELESS TRANSMISSION OF ENERGY THOMSON. 251 



though the waves decay rapidly, and the system vibrates only 

 for a short time or until the energy of the charge is dissipated 

 in ether waves of exceeding high pitch into the surrounding me- 

 dium. Were there no energy lost in the gap itself for forming the 

 spark, and if the metal were a perfect conductor, the full amount 

 of energy represented by any initial charge would be dissipated in 

 the ether in these ether waves. Marconi, however, in his develop- 

 ment of wireless telegi^aphy did not use the complete Hertzian oscil- 

 lator. In setting up his transmitting antenna he took substantially 

 half an oscillator, the other half being, so to speak, a phantom — the 

 reflected image of the first half, as it were, in the surface of the 

 earth, generally the sea surface. It would be represented by taking 

 an extended copper sheet or surface coated with a fairly good con- 

 ductor to represent the earth's surface and mounting above it, but 

 insulated from it, a metal body, such as a vertical rod, which could 

 be charged and which 



could discharge to the 'o ' 



sheet through a small — -^ /-- — 



air gap. In this ar- /^^^^^^^nN 



rangement not only l/^//'^//\\^\^\ 



would waves be sent liiilil.K ^. '\\\jJ 



mi 



out into the surround- ^ 



ing ether space, but 



there would be cur- Fi6.2lA. 



rent traversing the 



sheet as waves of cur- /J^'^^x --'-^^^^^^^ ^— ^ 



rent around the spot '~^^^n^\ /%'^:=:^^^\ /'^/''^3-"^'^\ /^ 

 where the discharge ^ V\\\\\\^ h/VC-'^^^ ^M^J^~'^-^^^\^ ^Si 

 of the insulated bol, jJMl/Ljmt-^Ml 

 took place. In fact, I + + __^ - — ^ _^ + + 



think it would be pos- 

 sible to represent exj)erimentally a modern wireless system with a 

 diminutive antenna to represent the transmitting station, and ex- 

 tended copper sheet to represent the earth's surface, and with investi- 

 gating or receiving antennae set up here and there or moved from 

 point to point on the extended surface. 



Here, although the disturbance and the energy conveyance is in 

 the ether around the antenna (or the part representing the half of 

 the Hertzian oscillator), the energy is guided in its direction by the 

 current in the sheet representing the surface of the sea, just as in 

 the wire transmission the energy is guided by the wire as a core. 

 On account of the enormous extent of the earth's sea surface, there 

 is no need of a return circuit. The energy sent out moves in all 

 directions, guided by the conducting water surface or land surface, 

 as the case may be. There will necessarily be a rapid attenuation 



