27# Prof. L. Natanson on the Molecular Theory 



secondary waves crossing the plane in the negative direction 

 of the axis of z : 



^---W&i**-***- ■ - • (3) 



The actual electric field induced at M, say (Ej, may be 

 considered as compounded of (E^ 2) ) + , (E^ 2) )_, and the 

 primary effect E^ I; directly due to the incident wave : 



L i(6c — 1)J 



III this equation it will be observed that the occurrence of 

 the term containing e «K*— a*-^) points to a train of waves 

 transmitted through the medium with vacuum phase- 

 velocity c and without any loss or enfeeblement whatever. 

 Among the observed phenomena of light an effect of this 

 kind is unknown; and if we confine ourselves to the con- 

 sideration of steady states, we are justified in denying the 

 possibility of its realization. In the subsequent treatment 

 we will assume that electromagnetic waves are always 

 Obliterated as they advance in the medium. To satisfy 

 this condition it is requisite that terms such as those to 

 which we allude should remain inoperative in our solutions. 

 The word is so significant of our meaning that there is 

 presumably no need for apology in using it for the sake of 

 brief terminology. 



We have accordingly 



A il) e in(p-q) = -^_^_ ( 5 ) 



and 



(E*)= ^^" fc+ » ; . • • (?) 



Let us determine the corresponding magnetic effects 

 generated at the point M, supposing as before that the 

 state of the system has become thoroughly steady. Reverting 

 to §4 we easily find, for the secondary positive magnetic 

 effect 



( H f\= 2 i^T ) {^ t - bz+l) -^ i - az+9 h ■ (7> 



and for the secondary negative magnetic effect 



(^)_ = ^^«ftp-»»+j) (8> 



I yOC ~j~ -L ) 



