284 ON THE REFLEXION AND REFRACTION OF LIGHT. 



The principal object of this supplement has been to put the 

 equations due to the surface of junction of two media, and be- 

 longing to light polarized perpendicular to the plane of inci- 

 dencej under a more simple form. The resulting expressions 

 have here been made to depend on those before given in our 

 paper on Sound, and thus the determination of the intensities of 

 the reflected and refracted waves becomes in every case a matter 

 of extreme facility. As an example of the use of the new 

 formulas, the intensities of the refracted waves have been de- 

 termined for both kinds of light : the consideration of which 

 waves had inadvertently been omitted in a former communi- 

 cation. 



Perhaps I may be permitted on the present occasion to 

 state, that though I feel great confidence in the truth of the 

 fundamental principle on which our reasonings concerning the 

 vibrations of elastic media have been based, the same degree 

 of confidence is by no means extended to those adventitious 

 suppositions which have been introduced for the sake of sim- 

 plifying the analysis. 



Let us here resume the equations of the paper before men- 

 tioned, namely, 



dx dy dx dy 



I 



(when aj = 0) (17), 



d(D (fair ud) d"*!/* 

 dy dx dy dx 



where u and v, the disturbances in the upper medium parallel to 

 the axes x and y, are given by 



_^> ,ty 

 " dx + dy ' 



_ 

 ~~~ 



