The Hawaiian star. [volume] (Honolulu [Oahu]) 1893-1912, 1893-12-16
NO. aa4.
LleHr. COLOR AND lie EYE.
Extraordinary Differences In the Power Of
Nision---nme Intercsting Experiments.

Extraordinary Differences In the Power Of
/ Nision--snme Interesting Experiments.
While the eyesight of many persons 10
defective, a .till greater number have eyes
which are unlikrcacn other In seeing power.
/ In fact, Ihany practically make use OF one
eye only the other having been originally
little detective was by degrees called on
for duty less and less and accordingly de
generated.
one gentleman could see with his right
go ,Ae figures on the face of clock five
righths OF an inch high at ~ feet, while he
'ould see them a. clearly with the left eye
.iy at e. nt inches distance. and curiously
enough tpi- extraordinary difference In the
1wers of vision Of both eyes was not de-
te'ted 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 IL will
be reality Understood that .s,lch cases
considerable diifnr, noes in ths<bowers of
the eyes nnaysfxist Without King suspect
ed. Sir John Herschel mentions the case
of an elderly person who by chance made
the unpleasant discovery that he was alto
gether blind in one eye
Some simple and easily performed ex-
perimeuts give interesting glimpses into
the constitution of the eve. Go into adark
room with q candle. Looking at the wall.
which should be Of a uniform dark tint, ON.
moving the candle mp and down close to
the outer side OF one eye so that the light
falls very obllQuely onto it, one of what
are called "purkinje's figures will be
seen. This is an appearance OF a celles Of
diverging and brauched red lines on dark
Held, In the interspace of two or three of
which Is sort OF cup shaped disk.
These lines are the blood vessels of the
retina, and the disk 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 a distance OF about two inches
on a level with the point toward which the
eye is directed and q little to the right or
left of II, when faint light may be seen
moving in the opposite direction to the can
die and on the lower side Of the point looked
at.
This light, II more nearly inspected, is
seen to be an inverted image of the candle
flame, equal in size to il, but very faint.
and j., in fact, the light of the candle re
hected from the lens of the eye. Other in
ternal parts Of the eye also reflect some OF
the light that fall, into ii, but the images
formed 10y them are not so easily seen.
1t is well known that the pupil contracts
mechanically la bright light and expands
in faint light, hut il has been found that
to some extent this change is under the CON
troll of the will. A scientific observer writ
ing on this subject says That when fronting
a window or other light he can make the
pupil expand or contract at the desire of
any one looking ilL-~sris eyes
The pupil Is ontracted while he steadily
looks at the light, and when he wishes to
expand 1t all that is necessary is to take his
attention away from the eye and fix It ON
some other part of the body without NOV
ing his eyes. This he does, say, by Bit
ing his tongue, pinching his arm or in
some such way The sensitiveness Of the
retina is diminished by this means, aud the
pupil dilates 1t contracts again when the
mind is once more recalled TO the eye and
the bright light.--1it- Bits