The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1902-03-09
SIGHT OF THE EYE.
Interesting Experiments That We Can
Make.

Harvey Sutherland, in Ainslee's Magazine
The sight of the eyes, as we say when we
talk like common folks, or the pupil, as we
say when we want 20 have it known that
pa was rich enough TO send to college,
is that little hole in the curtain that hangs
before the lens 1t looks like black spot,
just as the window of the house across the
way looks black TO me on a bright day be-
cause comparatively little light comes from
the room behind it. The black spot was
called the sight because sight was supposed
TO reside in 1t. And now what little boy or
girl can tell me why it is called the 'pu-
p1?' No hands up? Why, children! Think
now. What is a pupil? Yes, that's right,
one that goes to school or takes lessons.
take lessons are usually little folks and
pupil really means "a little girl" and
that black spot is named because the re-
Election of the person looking into anoth-
err eye Is so small. How expressive that
is! How much more expressive than any
word Of English origin could possibly be!
And how thankful we ought all to be to
our dear teachers who labor faithfully
to beat "bonus-a-um, boni-ae-t" into our
heads and to confer upon US the priceless
boon Of a thorough knowledge Of Latin,
printed in characters that Cicero would be
puzzled to make out and pronounce after
method whose only certainty is the GER
tainty that Cicero did not so pronounce.
Every day 1 rise out of my bed 1 rejoice
to remember that l spent six years study
ing Latin What though 1 cannot now or
ever could so much as call cab in Latin?
The mental discipline, man, the mental
discipline
"The rays of light from the outside world
pass through this little hole and are TO-
cussed on the back wall OF the eye. To
find out how big the picture in the eye Is
of any given object, measure the object and
its distance from the eye, reduce these to
millimeters; multiply the diameter of the
object by Is and divide it by its distance
from the eye plus 7. Example: The lower
case type on this page is one-sixteenth of
an inch high: You probably hold the maya
zine about twenty inches from the eye.
The image in your eye of one of the letters
in this word is about 1900 of an inch high
When the image of line is 1850 of an
inch long on the best spot of the retina for
seeing, the very acutest and most care
fully trained eye may distinguish the ends
of the line as separate points, for, though
one of the cones with which this fine seeing
is done is only 1920 of inch across, the
picture of the line may fall on two cones
ana be seen as two points. A bright point
however, may be seen If its image occupies
only very small part of one cone. Thus
an object 1-625 of an inch across, held an
inch from the eye and making an image
only ZIP 500 of an inch across, is distinctly
visible The limit of things visible is still
farther off. Objects as small as the 1000
of an nch in diameter. about one-tenth Of
the length of q wave of light, can be seen
with the highest powers of the modern mi
How clumsy the vision is, except in this
goodts spot of the eye may be noted if YOU
make two dots one-sixteenth of an inch
apart and look little to one side of them
so that their picture falls on another part
of the retina. They look if they were
one line The good spot is painted yellow
The fibers of the optic nerve. which spread
out over nearly all the inside OF the eye
are almost absent here, and there are rods
as well as cones sticking their points into
the pigment cells still deeper in the wall OF
the eyeball. But in the very bottom of the
wrinkle that Dame Nature made, in the
grooves of the yellow spot where the very
closest seeing is done, there are only cones.
AS nearly as l can find out the fibers OF
the optic nerve do not seem to have much
TO do directly with hemstitching and read
ing the want ads"