[J. M.--D. P. WATERS--NASO--L. X. R.--W. J. B. S.--B. R. J.--MARY, &c.,
have also furnished us with Replies to this Query.]
_Optical Phenomena_ (Vol. v., p. 441.).--You have not yet published any
satisfactory reply to the optical Query of N. B., at p. 441. of the present
volume. I apprehend there is not much difficulty in finding the solution. I
attribute the phenomenon to the refraction of light through a stratum of
air that is more dense than the surrounding air. Every solid is coated by
such a stratum. This is the well-known fact of _adhesion_ {617} alluded to
by Liebig, in his _Letters on Chemistry_, 1st series [2nd edit. by Gardner,
p. 16.]