The Wichita daily eagle., 1893-12-06
ODDITIES OF THE EYE.
Singular Effects of Lights and COlors on
the Windows of the Soul.


the Windows of the Soul.
While the eyesight of many persons
is defective, a still greater number
have eyes. which are unlike each other
in seeing power. In fact, many prac-
tically make use of one eye only: the
other, having been originally little
defective, was by degrees called on for
duty less and less, and accordingly de-
generated. One gentleman is reported
who could see, with his right eye, the
figures on the face of clock five
eighths of an inch high at twelve feet,
while he could see them as clearly with
the left eye only at eight inches dis
tance, and, curiously enough, this eX-
traordinary difference in the powers of
vision OF both eyes was not detected by
him until he had reached middle age.
Many people are unable to keep one
eye shut and the other open at the
same time. This is especially common
with children, but less frequent with
adults, and it will be readily under
stood that in such cases considera BILE
differences in the powers of the eyes
may exist without being suspected.
Sir John Herschel mentions the case of
an elderly person who by chance made
the unpleasant discovery that he was
altogether blind in one eye.
Some simple and easily performed
experiments give interesting glimpses
into the constitution of the eye. Go
into dark room with candle. Look
ing at the wall, which should be a uni
form dark tint, on moving the candle
up and down, close to the outer side of
one eye, SO that the light falls very
obliquely into it, one OF what are called
''Purkinje's figures" will be seen. This
is an appearance of a series of diverg
ing and branched red lines on dark
field, in the interspace of two or three
of which is a sort of cup-shaped disc.
These lines are the blood vessels of the
retina, and the disc is the yellow spot
or most sensitive part of the eye.
In the same situation. looking still at
the dark wall and keeping the eye fixed
on one point. hold the candle at arms
length and move it to and fro for dis
tance of about two inches on n level
with the point toward which the eve is
directed and little to the right or left
of it, when faint light may be seen
moving in the opposite direction to the
candle and on the lower side of the
point looked at. This light, if more
nearly inspected, is seen to be an in
verted image of the candle fame,
equal in size to it. but very faint, and
is, in fact, the light of the candle re-
fected from the lens of the eye Other
internal parts of the eye also reflect
some of the light that falls into it, but
the images formed by them are not SO
easily seen.
1t is well known that the pupil con-
tracts mechanically in bright light and
expands in faint light: but it has been
found that, to some extent, this change
is under the control of the will A sci
entifc observer. writing on this sub
ject, says that when fronting a window
or other light. he can make the pupil
expand or contract at the desire of any
one looking into his eye. The pupil is
contracted while he steadily looks at
the light, and while he wishes to ex-
pand it all that is necessary is to take
his attention away from the eye and fix
1t on some other part OF the body with
ont moving his eyes. This. he does.
say, by biting his tongue, pinching his
arm or in some such way. The sensi-
tiveness of the retina is diminished by
this means and the pupil dilates It
contracts again when the mind is once
more recalled to the eye and the brigh.
Y Journal