214 JAMES CLEHK MAXWKLI* 



According to tho former, tho waves do not travel in 

 the wire at all ; they travel through the air alongside 

 the wire, and the wave length observed by Hertz 

 ought to have been the same as in air. According to 

 Von Helm hoi tz, the two velocities observed by Hertz 

 should have been different, as, indeed, they were, and 

 the experiment appeared to prove that Maxwell's 

 theory was insufficient and that a more general one, 

 such as that of Von Ilclmholu, was necessary. J5ut 

 other experiments have not led to the same result. 

 Hertz himself, using more rapid oscillations in some 

 later measurements, found that the wave length of 

 the electric waves from a given oscillator was the 

 same whether they were transmitted through free 

 space or conducted along a wire.* Lecher and J. J. 

 Thomson have arrived at the same result ; but tho 

 most complete experiments on this point are those of 

 Sarasin and De la Rive. 



It may be taken, then, as established that 

 Maxwell's theory is sufficient, and that the greater 

 generality of Von Helmholtz is unnecessary. 



In a later paper Hertz showed that electric 

 waves could be reflected and refracted, polarised and 

 analysed, just like light waves. In his introduction 

 to his " Collected Tapers" ho writes (p. 10) : 



44 Casting now a glance Wkwartis, we see that ly tho 

 aUove .sketched the propagation hi time of a 



* Hertz'a original result* were no doubt aftVrteil by waves 

 renYit-d from the walls and iloor of tho room in whirh he worked. 

 An iron stove also, which was near his apparatu*, may have had 

 a disturbing influence; hut fur Ml this, it is to hi* genius and hi.-* 

 brilliant achievement* that the complete establishment of Maxwell** 

 theory is due. 



