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VI. Supplement to a Memoir on the Reflexion and Refraction of Light. 

 By G. Green, Esq. B.A. of Caius College. 



[Read May 6, 1839.] 



In a paper which the Society did me the honour to publish some time 

 ago, I endeavoured to determine the laws of Reflexion and Refraction 

 of a plane wave at the surface of separation of two elastic media, sup- 

 posing this surface perfectly plane, and both media to terminate there 

 abruptly : neglecting also all extraneous forces, whether due to the action 

 of the solid particles of transparent bodies on the elastic medium, which 

 is supposed to pervade their interstices, or to extraneous pressures. I am 

 inclined to think that in the case of non-crystallized bodies the latter 

 cause would not alter the form of our results in the slightest degree ; 

 and possibly there would be some difficulty in submitting the effects 

 of the former to calculation. Moreover, should the radius of the sphere 

 of sensible action of the molecular forces bear any finite ratio to X, the 

 length of a wave of light, as some philosophers have supposed, in order 

 to explain the phenomena of dispersion, instead of an abrupt termination 

 of our two media we should have a continuous though rapid change of 

 state of the ethereal medium in the immediate vicinity of their surface of 

 separation. And I have here endeavoured to shew, by probable reasoning, 

 that the effect of such a change would be to diminish greatly the quan- 

 tity of light reflected at the polarizing angle, even for highly refracting 

 substances: supposing the light polarized perpendicular to the plane of 

 incidence. The same reasoning would go to prove that in this case the 

 quantity of the reflected light would depend greatly on minute changes 

 in the state of the reflecting surface. I have on the present occasion 

 Vol. VII. Part I. P 



