BiO Mr. Gr. TJ. Yule on the Passage of Oscillator 



The intensity of the ray transmitted by this slightly absorbent 

 layer was determined by an electrometer E placed at a quarter 

 wave-length (2*25 metres) from the closed end of the circuit. 



Fig. 1. 



A £ 



-£!«.' 



This intensity varied periodically with the thickness of the 

 layer, as in the analogous case of a ray of light and a " thin 

 plate." 



The layer AB was what Boltzmann has termed a " con- 

 ducting dielectric," i. e. both its conducting and dielectric 

 properties were of importance. The theory of a non-con- 

 ducting plate is much simpler : a problem equivalent to it has 

 recently been treated by Dr. E. H. Barton *, to whose work 

 I shall have several occasions to refer. In the more complex 

 problem I have assumed, we have simply a plane-fronted 

 damped wave-train travelling through an insulating medium 

 and falling at normal incidence on an infinite slab of con- 

 ducting dielectric. The magnetic permeability of both the 

 plate and the surrounding medium are taken as unity. 



The theoretical transmission-curve obtained on these assump- 

 tions does not agree well with the experimental one, the 

 divergence being the same in sign and order of magnitude 

 as that noticed by Dr. Barton in his case. We have in fact 

 idealized the experimental facts too far in endeavouring to 

 simplify the analysis : the electrolyte was not at all infinite in 

 extern, and at least one important correction is obviously 

 necessary (section VI.). The experiments can only be re- 

 garded as a very rough illustration of the problem, and as 

 giving the raison d'etre of this paper. 



The general results obtained seem to be of considerable 

 interest. The intensities of the reflected rays, the phase- 

 changes, and so on, for damped wave-trains reflected from 

 such a plate differ from those for steady rays in some cases 

 very considerably. 



For convenience and brevity, the surrounding medium is 



* Preliminary Paper, Proc. Roy. Soc. vol. liv. p. 85 ; more fully in 

 Thesis for the D.Sc. London, 1894, or Wied. Ann. vol. liii. p. 513, 1894, 

 Final paper, Proc. Hoy. Soc, read April 1893 (not yet published). 



