The new North-west. [volume] (Deer Lodge, Mont.) 1869-1897, 1885-07-17
COLOR
INABILITY TO DISTINGUISH RED THE
MOST FREQUENT DEFECT.
Green the Next Color Most Frequently
Mistaken Men More Affected Than
women-Tests Of Color Blindness
Various Experiments
IDr. Genrre s. Munson.l

The most frequent defect in color-blind-
moss Il the inability TO distinguish rcd. A
distinguished professor in an English uni
verIty once wore n scarlet gown through
the streets much 10 the amusement Of many
who Jaw him On being asked by q friend
what appeared TO him 70 be the color OF this
robe, he answered, pointing TO some ever
greens near by; ut seems TO me to resem-
BILE those ms closely as possible" The next
color most frequently mistaken for some
other Is green. The importance Of this de-
feet Is estimated by the frequency Of its
Occurrences. IL IL occurs only once In 10. 900
persons, 10 Is Of course Of 10 Importance
than IL happening once In 100.
Men are more frequently effected with
this defect OF vision than women. The de-
feet. when IL Is congenital, as 1t Is In most
Of the cases under the observation OF physi-
clans. Is incurable IL ~ sometimes induced
by immoderate use OF tobacco or liquor. As
many as one IN twenty-five Of the men en-
ployed on dimes Of travel are affected by this
inability to distinguish red from green. The
color blind In case Of accident by travel on
land and sea can not readily be detected be-
cause of the difficulty OF tracing the causes
OF tho accident One thus affected can not
tell n 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 we'll
one can name colors. but how much he sees
them. IL two letters be drawn, one red and
another green, on background, q person
who Is red blind will distinguish only the
green letter, and party who is green blind
would fail TO distinguish or SEQ the green
letter. In other words, to tho first the red
La nj ~ t,a
green. The red blind will place purple or
q green alongside Of rose color, supposing
them all 30 be the same shade. The green
blind will confound 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 q, 600
employees Of the Pennsylvania railway
have been found totally color blind, and
10 per cent more or less affected
with this defect Of vision. Five per cent of
the same were found with imperfect hear
ing. In this city lives well known animal
painter who Is entirely color blind. He So
lects his color not by knowing tho color
itself, but by reading their names on the
tubes lie employs usually only black,
brown and white In his work.
DR. Jsffries, Of Philadelphia. instituted
very efficient test OF color-blindness by sus-
pending numbered sksins Of worsted Of diff
ferent colors from a rod. The standard
colors Of rose. red. and green. with all the
various shades Of these colors, were num-
bered with the odd numbers All other col.
ors 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 IL any so named
were among those numbered with the even
numbers 1t was seen at once that they were
unable TO distinguish colors