The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1885-05-28
Color Blindness.
Red nnd Green Most Bother Those whose
Vision Is Imperfect.

| lErom Paper by DR.. George S. Munson Of New
York;
The most frequent defect in color blind
ness is the inability to distinguish red. A
distinguished professor in an English uni
versity 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 this
| robe, he answered, pointing to some ever
green's near by: SIT seems to me to resem-
BILE those as closely as possible" The mex.
color most frequently mistaken for some
other is green. The Importance of this de-
feet is estimated by the frequency of its oc-
currence. If it occurs ouly once in 10000
persons, it is of course of less Importance
than if happening once in 100 Men are
more frequently affected with this defect In
vision thau women. The defect, when il is
congenital, as it is in most of the cases under
the observation of physicians. is ineurabe.
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 inability to dis
tinguish red from green. The color blind
in case Of accident by travel on land and sea
cannot be readily detected because of the
difficulty of tracing the causes of the acci-
dent. One thus affected cannot tell a red
from green light, but one of these lights
appears 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. II two letters be drawn, one red and
another green, on background, a person
who is red blind will distinguish only the
green letter, and a person who is green
blind would fail to Distinguish sor see the
green letter. In other words, to the first the
red color is suppressed and 10 the second the
green The red blind will place a purple or
a green alor gside of a rose color, supposing
them all to be the same shade. The green
blind will confound the blue and the gray
with the rose color. The test for an engi-
neer 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 $4,000 employees of the Penn
sylvania 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 imperfect hearing
In this city lives well known animal paint
er who is entirely color blind. He selects
bis color not by knowing the color itself,
but by reading their names on the tubes
He employ es usually only black, brown and
white in his work
DR.. Jeffries of Philadelphia instituted a
very efficient test of color blindness by sus-
pending numbered skeins of worsted of diff
ferent colors from rod. The standard
colors of rose, red, and green, with all the
various shades of these colors, were nun
bered with the odd numbers. All other colors
were numbered with even numbers. The
persons examined for color blindness were
invited to match shades of the three named
before as The standard, and if any so named
we're among those numbered with the even
numbers it was seen at once that they were
unable to distinguish colors.