Middlebury register. (Middlebury, Vt.) 1886-1937, 1889-12-06
COLOR BLINDNESS.
HOW EYESlGHT is TESTED BY RAIL
ROAD PHYSICIANS.

Applicants FOR Positions Put Through the |
worsted and Blackboard Exercises-Four
Per Cent. Are Found to BE Unfit for the
Responsible Places.
"What color is that?"
The speaker was DIR. B. F. Clark, ply
stefan of the g., II. and d. railroad.
A tall, gangle legged man stood before |
a table on which were piled in great
confusion several hundred skeins of diff
ferent colored worsteds. They were of
every shade and hue, from pea green to
Mazarin blue, from solferino red to
purple, gray, cherry and brown.
The doctor continued: 1.-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 them
selves.
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 over 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, con-
ductor, 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.
HIS PECULIAR WEAKNESS.
Now to determine what this mans
chromatic defect is we select pink
skein.
"If he is red blind he will pick out blues
or violets, or both. If he should be green
blind he will select grays and greens or
blue green's Sometimes, to verify the
two previous tests, we 10y 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 blind?"
"About A per cent. are color blind
That is one out of every twenty-five in
dividuals. There are more red blind than
any other color"
anime the men by the lamps. 1t is one
of the most difficult things to stain the
glass regularly. When the glass is
blown it cannot be made all 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 a greater luminosity, while the
other is a very dull light. There may be
dust or steam over the glass, and the
light will be darker. A dirty white flag
to one color blind would be taken for a
green flag, which means safety. They
would take a dirty dark green for red
which means danger. This would lead
to endless confusion"
''Do you believe this to be congenita
defect
"Yes; but it may also arise from dis
ease, injuries and the excessive use Of
tobacco and alcohol. In one family
know Of four who are color blind. two
brothers and two sisters; in another
family an uncle and a nephew"
DO you examine for anything ese?"
"Oh, yes. 1t is just as important t.
examine for vision and hearing as it il
for color blindness. In order to make tn,
test for vision this is the programme:
test plate containing letters that can b,
seen at 200 feet and twenty feet, twent,
feet being the normal eye. is placed a
one end of the room.
The room is darkened. The patien
placed twenty feet distant, and then i
requested to cover one eve while tn
other is being examined. If he sees wha
we call twenty twentieths-that is. tn
letters representing twenty feet-he ha
normal vision. Both eyes are put to thi
test-first the right. then the left. If h
has vision in both eyes of twent,
fifteths minus-that is to say, if he can
see at twenty feet what he ought to Sc
at fifty-he is rejected, provided glasse
don't improve the vision. If man can
see that big B, the large letter, which h
/, ought to see at 200, at twenty feet wit
only one eye, then he has practically oni
one eye, and there have been several eS
amined who never knew that they coul
not see out of only one eye."
TESTING FOR HEARING.
"How do you test for hearing?"
"With my watch. The man is requil
ed to cover up his eyes and place m
watch to his ear, gradually removing
T. away until the exact distance that h
.. can hear the ticking is known. He say
' NO when he ceases to hear it. Now
two-thirds of all the engineers are har
of hearing, or, better, defective in tn
= right ear, which is due to their leanin
: out of the cab window, coming in col
> slant contact with the wind; that is [
!, say, the force of the wind coming in COZ
slant contact with the drum of the ear
. becomes affected. The constant pressur
. on the drum of the ear has the effect {
retracting it. 1t becomes concave. tn
range of vision is also tested. This
done by placing a man twelve or eigh
cen inches from a blackboard. He is r,
. quested to keep his eye directly on
: chalk spot, which is on a level with I'll
= eye, the other eye being closed. He
= directed to say Yes the moment he see
,l,,t