Sullivan republican. [volume] (Laporte, Pa.) 1883-1896, 1889-11-29
COLOR BLINDNESS.
HOW DEFECTIVE VISION is TEST
ED BY A DOCTOR.
Many Strange Mistakes Sometimes
Made by WOuld-Be Railroad Men
"A Man Who Could Not Tell
Cherries From Leaves
nWhat color is that?"

physician of the c., III. and d. Railroad.
A tall man stood before table on
which were piled in great confusion sew
eral hundred skeins of different colored
worsteds. They were of every shade
and hue, from pea green to mazarine-
blue, from solferino red to purple, gray,
cherry and brown.
The doctor continued: "The object
of this test is to select the light and
dark shades Now, I'll go on and select
them first" and the doctor put all the
light and dark shades running from pea
green to dark green in little pile by
themselves. The man watched him
closely, and the greens were all thrown
back into the heap, and the man began.
"Don't let your hand run over the
worsted, but let your eye do the work, "
said the doctor, as the man began fumb
ling the pile.
The man put gray and light yellow
and brown together.
"That'll do" said the doctor.
"That man is not fit for an engineer,
fireman, brakeman, switchman, conduc-
tor, or, in fact, any one who has use for
signals He is color-blind. That test
alone is sufficient for any railroad, army
or navy. Now to determine what this
mans chromatic defect is we select a
pink skein. If he is blind he will pick
out blues or violets, or both. If he
should be green blind he will select
grays and greens or blue greens. Some
times, to verify the two previous tests,
we lay out the red skein, and the party
selects browns or greens in their different
shades"
"What percentage do you find, of all
those examined, to be color -blind9"
"About four per cent. are color-bhnd.
That is one out of every twenty-five in
dividuals There are more red blind than
any other color. The c., H. and d.
road has only the green and red lights,
other roads have white, red and green. "
"Why do you have worsteds as the
test, doesn't the Pennsylvania Company
use stick9"
eyes, they use a stick with about
forty different colored skens, but worsted
is better than silk because the dye is per
feet and not glaring. 1t is often asked
why we don't examine the men by the
lamps 1t is one of the most difficult
things to stain the glass regularly. When
the glass is blown it can not be made al
the same color. Then, if the glass is
thicker the color will be darker. Again
sometimes the wick is turned higher
! and then the light has greater lumin
osity, while the other is a very dull
| light. There may be dust or steam ovel
the glass, and the light will be darker
A dirty white flag to one color-blint
would be taken for green flag, which
means safety. They would take dirty
dark green for red, which means danger
This would lead to endless confusion"
elbow have you proved this, doctor9'
"Why, l recollect taking one mar
down to the depot and asked him t.
name the colors from the creek up, whicl
he named all right with the exception o
the last lamp-the first one was from tn
depot--that lamp being covered witt
dust and the wick turned low. He mis-
took the green for the red, and said 'the
switch was wrong We then approached
the lamp, and he did not discover hi
mistake until he was within about thir
ty-five or forty feet. There are Otter
cases where men who are color blind Gu
knotches in their stricks. l had on
man who said he could not pick cherrie
could not tell them from the leave
only by their form. He said the sur
roundig hills were red. And that tn
outside of watermelon was red and tn
inside green, but he knew from hearsa.
that the opposite was true"
''Do you believe this to be congenita
defect2"
eyes; but it may also arise from dis
ease, injuries and the excessive use of to
bacco and alcohol. In one family
know of four who are color blind, tw
brothers and two sisters; in another fam
lily an uncle and a nephew"
''Do you examine for anything else ?"
ooh, yes. 1t is just as important t
examine for vision and hearing as it
for color blindness In order to max
the test for vision this is the programme
A test plate containing letters that can b
seen at 200 feet and twenty feet, twent