The eye the most important of our organs--Popular description
of it--The eye is the most fertile source of mental
illusions--Disappearance of objects when their images fall
upon the base of the optic nerve--Disappearance of objects
when seen obliquely--Deceptions arising from viewing
objects in a faint light--Luminous figures created by
pressure on the eye, either from external causes or from
the fulness of the blood-vessels--Ocular spectra or accidental
colours--Remarkable effects produced by intense
light--Influence of the imagination in viewing these
spectra--Remarkable illusion produced by this affection
of the eye--Duration of impressions of light on the
eye--Thaumatrope--Improvements upon it suggested--Disappearance
of halves of objects or of one of two persons--Insensibility
of the eye to particular colours--Remarkable
optical illusion described 8