Miscellaneous optical illusions--Conversions of cameos into
intaglios, or elevations into depressions, and the
reverse--Explanation of this class of deceptions--Singular
effects of illumination with light of one simple colour--Lamps
for producing homogeneous yellow light--Methods
of increasing the effects of this exhibition--Method of
reading the inscription of coins in the dark--Art of
deciphering the effaced inscription of coins--Explanation
of these singular effects--Apparent motion of the eyes
in portraits--Remarkable examples of this--Apparent
motion of the features of a portrait, when the eyes are
made to move--Remarkable experiment of breathing
light and darkness 98