290 ON THE REFLEXION AND REFRACTION OF LIGHT. 



that this is the case with diamond at the proper angle. But the 

 phenomena observed by Professor Airy appears to him entirely 

 inconsistent with this result (Vide Camb. Phil. Trans., Vol. IV. 

 p. 423) ; what immediately precedes seems to render it probable 

 that considerable differences in this respect may be due to slight 

 changes in the reflecting surface. 



