The Washington times., 1915-08-25


i is an elastic. globular kingdom
with innumerable exits and en-
frances! 1t has. nevertheless, two
royal vestibules. One of these is the
muscles and the other Is the eyes.
These two make mental life very rich
for many missing senses. which other
creatures have and man lacks.
Love, Hope and Joy. fair pleasures
smiling train,
Hate. Fear and Grief. the family Of
pain;
bounds confined
Make and maintain the balance OF
the mind.
Much Of these are woven into the
woof and warp Of life by way Of the
The eyes have been called "the win
more than mere embrasures; they are,
In fact, causeways. and royal ap-
proaches to the intellect
When a real thing In the universe
strikes the eyes the external object re-
outer surface Of the eye. pass thence
into the small hole or pupil, where
they spread out like the light from a
motion picture lantern.
takes hold OF these reflected rays Of
the object outside and rearranges them
much us the lens does IN a photo
graphic camera. II focuses them upon
as the Kodak len. paints them upon the
film or plate in the back Of the camera.
How Your Lenses Work.
II you split open the eyeball Of rat
or rabbit YOU can observe how trans
parent the eyeball, its fluids. and the
lens all are. There is a clear. jelly-like
in, pf tho lens and more
between the lens and the retina.
The eyeball OF a white rat or white
rabbit is almost transparent even 10 its
walls. II such an eye Is placed In a
front Of your eye you will see mirrored
on the retina-the back surface-an
image upside down OF things around.
Just SUCH an inverted Image Of out
side objects In focus Is made on the
photogra phic plate or film when pic
ure is snapped. The geometry and laws
Of optical glassware. lenses. convex and
concave surfaces all show how the rays
from the feet 60 upward and those from
the head downward-if the object i'm
aged Is a man-so that things are seen
and photographed "downside up with
care"
Parallel rays OF light reflected from
real objects in the external world enter
the pupil-which widens or narrows In
order to keep the rays parallel and cut
out the non pa rallel ones-pass through
the "humor' or transparent Jelly and
strike the lens.
The lens may be thought of as two
watch crystals cemented together with
one butt end pointing forward and one
into the back chamber Of the eyeball.
The lens however. Is alive. 1t Is not
dead glass. 1t can bulge and shrink
together as your eye muscles pull or
relax.
Thus its focus changes. Instead Of
pulling your camera In and out as you
do to make your focus in the photo
graphic apparatus. the eyeball itself
lengthens and shortens but slightly. The
lens bulges and collapses instead.
The front surface OF the eyebail as
we'll as the rear interior wall all spread
the light rays so that the focus is main
tained clearly. While 1t Is true that the
camera in some respects surpasses the
that physiologists often forget that the
eye and all its segments are alive and
can adapt Itself within limits to vari-
Gus unexpected difficulties.
When the layman tries to learn about
optics he often finds himself puzzled by
men and scientists are seemingly un-
conscious Of the foreign tongues they
use.
An Unexplained Eye Mystery"
Thus you hear OF ''refraction' of
lipht, Index OF refraction." convex"
"copcave." double convex double
concave." "cornea" and many others.
In plain words. ''refraction" merely
means the direction and bent of the
rays Of light A hollow. like a saucer
is concave; the opposite is convex. The
bulging front OF your eye is the cornea
As you know 1t Is convex. The hol-
lowed out inside OF the back wall is as
you face it from the front. concave.
Index OF refraction' expresses the
amount Of bend in the rays OF light as