Evening star. [volume] (Washington, D.C.) 1854-1972, 1895-01-19
PHOTOGRAPHS BY THE EYE
Why They Are Only Temporary and Cannot
Be Preserved
The UnsoIved Mystery of the Natura
Of Visual Purple-The Use
of Eyeglasses.

Written for The Evening Star.
The story recently told in the news
| papers about murderer's photograph pre-
served by the retina of the eye of the wo-
man slain is a wild absurdity-merely Q
repetition, in fact, of an oft-toId nonsense
tale.
The pictures formed by the eye are GER
tainly photographs. They are Impressions
registered upon a sensitive surface, which
in this case is the retina or nerve-screen
that lines the ocular camera. But they are
very fleeing. There is no conceivable way
of rendering them permanent. 1t will be
remembered that in the early days of pho
tographic art the problem to make
permanent the images formed. In the So
| luton of that problem constituted the real
invention of photography. At the pres
ent day the same puzzle obstructs success
in producing photographs in colors. They
can be made easily enough, but they fade.
it is practically certain that color photog-
raphy will eventually become an accom-
plished fact; but for obvious reasons there
will never be permanent eye photographs.
The human eye Is nothing more nor less
than little camera. Instead of a SenSi-
tive plate, it is provided with a transpar-
ent lining, through which are woven the
nerve threads that ramify in all directions
from the point where the optic nerve en-
| tiers the eye at the back. These nerve fila
ments in fact, are merely branches or ex-
tensions of the optic nerve. The optic
nerve, of course, comes directly from the
brain. The rays Of light proceeding from
an object enter the eye through the pupil
and are concentrated by the lens, which is
behind the pupil, upon the retina. Thus is
formed a picture of the object This pic
ture is transmitted by the nerve fibers to
the brain, and thus it is that one sees.
1t is still Mystery.
Between the retina and the outer coat OF
the eyeball is a membrane made up chief
ly of blood vessels and black pigment.
| This pigment is plentifully supplied in or
der to absorb the light, just the inside
of an optical instrument is biackened for
| the same purpose. The entire absence OF
| the pigment in an albino renders person
| or animal so afflicted extremely sensitive
| to light, which produces a dazzling effect.
The red blood flowing in the transparent
vessels unconcealed by the pigment shows
through the pupil and iris from the front,
and so an albino'S eye looks pink.
There Is a substance found in the eye
which is known as the visual purple" It
has been imagined that this purple has
something to do with the making of i'm
ages of objects seen, just as sensitive pho
tographic plates reveal pictures on the
application of certain chemicals. But the
fact is that nobody has ever been able to
find out with certainty anything worth
function is likely to remain Indefinitely
| mystery. As has been said eye photo
graphs are always fleeing; but everybody
has taken notice Of the persistence for q
time of images of objects that have been
gaZed at intently
Today the curative treatment Of the eye
may be said to be science more exact than
any other branch of medical KNOWLEDGE
How wonderful IT seems that the develop
ment of this science should be due mainly
to an instrument invented by man who
died only few months ego, OF course
Won Helmholtz Is referred to. 1t was he
who devised the little mirror with a hole
through 1t, by means of which the ply
stefan is enabled to examine the illunli-
mated interior of the ocular camera, so
as to discover at once anything that may
be wrong with ii. Before the invention Of
the ophthalmoscope all that was known
about the inside OF the eye was ascer-
tanned by dissecting the dead organ, Just
as is the case with the internal structure
of the ear at present. The science of treat
Ing the ear has never got very far because
Of the impossibility Of obtaining a view
of its inside works in a living person.
The Use of Glasses.
Whereas in earlier times a large per-
centage of human beings were afflicted
with defective vision for lack of proper
glasses, nowadays a simple pair of lenses
enables the rearsighted person to see as
we'll or nearly as well as the indivId-
ual with normal eyes. Only a genera
ton ago 1t was a common thing to
see people troubled with chronic sore
eyes, the complaint being due usually
to strain, caused by want of proper spec
tacles. Today sore eyes are a rarity, COM
paratively speaking, because people who
need them wear glasses q rule. The
first eyeglaSs mentioned in history was
used by the Roman Emperor Nero. He
was so nearsighted that he could not see
satisfactorily what went or in the circus.
He found that a concave emerald, which
was of the imperial Jewels, assisted
his vision remarkably. He employed IL
constantly, believing that its power In this
regard was due to some magical attribute.
A number of decisions about the eye are
popularity entertained even now. One OF
them is to the effect that nearsighted eyes
are apt to be exceptionally strong This
is the reverse of the truth. NearSighted
eyes are almost always weak eyes and are
apt to belong to weakly people. Another
common and very erroneous belief is that
the adoption of glasses should be put of
as long US possible by elderly persons, be-
cause they strain the eyes, and for the
reason that they cannot be given up IL
once adopted. Nothing could be more alb
surd than this idea. Eyes that need glass
es are under constant strain through not
of strain by adopting them. When adopted,
they prove such relief and SO great an
assistance to the vision that they are reyer
given up as a matter of course. What
lame man, II he could get new leg, would
throw 1t away?
Mayor Strong's Advice.
From the Philadelphia Press.
from called