344 O. Barus — Inversion in the Wave Mechanism 



two equations precisely alike except as to the variables I^and <y. 

 The clockwise and counter-clockwise contrast of (1) and (2) 

 has vanished. V/V^K is seen to be the common velocity of 

 the two waves, if waves there be. Applied to plane wave fronts 

 parallel to yz one obtains 



Y= A sin 2ir\^ - ~J 



NA sin 2tt 



( t _x\ 

 \T~Xj 



where JN~ is the index of refraction, T the period and X the 

 wave length in the given medium of permeability p and spe- 

 cific inductive capacity K. The two waves differ merely and 

 naturally in amplitude. They are alike in phase. Nothing is 

 left to recall the opposite signs of (1) and (2). The direction 



of common advance is +a?, when the direction of positive elec- 

 tric force is +y and of magnetic force +s, in english or clock- 

 wise coordinates. The wave follows the motor rule which, 



