Iron County register. [volume] (Ironton, Iron County, Mo.) 1867-1965, 1885-07-23
COLOR BLINDNESS,
Some of the Colors Which Persons of De
fective Vision Are Unable to Dis
iSI,

Some of the Colors Which Persons of De-
fective Vision Are Unable to Dis
tinguish.
The most frequent defect in color
blindness is the inability to distinguish
red. A distinguished professor in an
English university once wore scarlet
gown through the streets, much to the
amusement of many who saw him. On
being asked by friend what appeared
to him to be the color of his robe, he
answered, pointing to some evergreens
near by: at seems to me to resemble
those rs closely as possible" The
next color most frequently mistaken for
some other is green. The Importance
of this defect is estimated by the fire.
quency of its occurrence. If it occurs
only once in ten thousand persons. it is
of course of less Importance than If
happening once in one hundred. Men
are more frequently affected with this
defect in vision than women. The de-
feet when it is congenital, as it is in
most of the cases under the observa-
ton of physicians, is incurable. 1t is
sometimes induced BY immoderate use
of tobacco or liquor. AS many as one
in twenty-five of the men employed on
lines of travel are affected by this IN
ability to distinguish red from green.
The color-blind in case of accident by
travel on land or sea can not be de-
tected, because of the difficulty of
tracing the causes of the accident. One
thus affected can not tell red from q
green light. but one of the lights APP
pears darker or less bright to him than
the other.
The test of color-blindness is not how
well one can name colorS, but how
much he sees them. If two letters be
drawn, one red and another green. on..a
black ground, a person who is red blind
will distinguish only the green letter.
aid a person who is green blind would
fail to distinguish or see the green let
ter. In other words, to the first the
red color is suppressed and to the
second the green. The red blind will
place purple or a green alongside of
a rose color, supposing them to be the
same shade. The green blind will con-
found the blue and the gray with the
rose color. The test for an engineer is
not to name colors and shades of color,
but to know red as red and green as
green. and to match red with red and
green with green of their various
shades. Four per cent. of the fifty
thousand employees of the Pennsylvania
have been found totally color-blind,
and ten per cent more or less affected
with this defect of vision. Five per
cent. of the same were found with i'm
perfect hearing. In New York lives a
well-known an NAL painter who is en-
tirely co1or-blind. He selects his colors
not by knowing the color itself, but by
reading their names on the tubes. He
employs usually only black. brown. and
white in his work.
DIR. Jeffries. of Philadelphia, insti.
tuted very efficient test of color blind
ness by suspending numbered skeins of
worsted of different colors from a rod.
The standard colors of rose, red. and
green, with all the various shades of
those colors. were numbered W. tn the
odd numbers All other colors We're
numbered with the even numbers. The
persons examined for celor-blindness
were invited to match the shades of the
three named before as a standard, and
if any so named were among those
numbered with the even numbers it was
seen at once that they were unable to
distinguish colors.-F'rona a Recent Pa
7le3. bar DR.. Ge0roe s. MxuSen 1864,