THE WORLD BEYOND OUR SENSES 



existed. Its verification, in the hands of Heinrich 

 Hertz, a quarter of a century after, was the strong- 

 est support the ether-wave theory has yet received. 



If Maxwell's ideas were sound, a discharge of 

 electricity across a gap would set up vibrations in 

 the ether round about, just as a stone dropped in a 

 pond will set up waves that go travelling outward 

 in every direction. And Hertz found that this is 

 exactly what happens. It was this discovery which 

 made wireless telegraphy possible. These ether- 

 vibrations are called, in honor of their discoverer, 

 Hertz-waves. 



Hertz found that his electric-waves measured 

 about one hundred and fifty feet from node to node 

 that is, from the top of one wave to the top of 

 the next. The waves used by Marconi, in telegraph- 

 ing across the Atlantic, are considerably longer 

 than this six hundred feet or more. These waves 

 travel at the same speed as light that is, at the 

 incredible rate of 184,000 miles per second. Ap- 

 parently they go straight through walls and moun- 

 tains, and are only arrested by metal. Hence the 

 employment of a net-work of metal wires at the 

 iving-stations in wireless telegraphy. 



m an electric-wave one hundred and fifty feet 

 long to a light-wave measuring a few millionths of 

 an inch is a far cry. The gap is wide. Neverthe- 

 less, the scientific imagination bridged that gap ( 



