424 Professor Airy on the Phenomena of Newton's Ring*. 



surrounded by a bright blue ring - ; but the rings, without chang- 

 ing their character as to colour, diminished steadily till the 

 central spot was as it were squeezed out. Whether the only 

 diamond which I have used may possess any peculiarity which 

 distinguishes it from those used by Sir David Brewster I cannot 

 say. Meantime I may observe that the singularity in the re- 

 flexion at the surface of the diamond makes it not improbable 

 that there may be some singularity in the refraction also, and 

 renders a more extended inquiry into the laws both of its re- 

 flexion and of its refraction highly desirable. 



Observatory, G. B. AIRY. 



Feb. 16, 1832. 



