The Carolina Spartan. [volume] (Spartanburg, S.C.) 1852-1896, 1856-05-22
Signals and Color Blindness.

nicu"is uhu tUiOE DlluuutS.
We recently alluded to an article in
the last number of the North British Re
oteD, IN which it was stated-as taken from
DIR. Wilson's work-that one person out
of every eighteen was unable to distinguish
different coors. The subject is one which
deserves moro than mere passing notice.
If 1T be true that color blindness is as
prevalent as DIR. Wilson has stated, then
all the engineers and switchmen on our
railroads, and all the pilots on our rivers,
should be thoroughly examined respecting
their capacity to distinguish colored signals.
This is something that never has been
thought OF, aud yet we can easily conceive
what consequences might ensue on n rail
road by an engineer mistakiug red for
white signal. Red flags, red globes, red
lights, and other colored Signals, are used
on railroads and steamboats,, and no doubt
they always will be used, because they are
so convenient. While in themselves they
are good and necessary, it is the duty Of
those companies using such, to see to it,
that those whom they employ, are not de-
tective in recognising and distinguishing
them.
Although it is our opinion that color
blindness is not SO common as has been
| asseriedi still nothing should ba left in
doubt, when the safety of life is concerned.
as on our railroads and night steamboats,.
Color blindness is something that battles
the best opticians TO account for satisfactory
iy-indeed the power of vision, in itself, is
Shrouded in much mystery, like that Of
every other sense man possesses, As far
back as 1854, Dr. Tuberville, of Salisbury,
Eng described the case of young female,
who could see very well, but no color be-
sides black and white; and singular TO re.
late, Sue could sometimes see to read in n
dark room. The famous chemist, DIR. Dal-
ton, was unable TO distinguish between red
and green colors; and Dugald Stewart, the
Philosopher, had the same defec. of vision.
lhls defect of vision has been long known
10 have had an existence, but was suppos-
ed to be limited TO very small number of
PERSONS. DIR. Wilson'S experiment were
instituted 10 discover the extent Of color
ohuaness, and, ii possible, its nature. Its
prevalence has astonished himself. Out
OF /, lo4 persons examined indiscriminatelv
he found G5 defective in distinguishing
colorS
IL u ana green are often coufouuded
together, and some persons that could dis
tingulsh these within one foot Of their eyes.
failed to do so when they were removed
from twelve to fifteen feet. These persons
would not answer for safe signal men. The
greatest number contound blue with green.
and the next greatest number confouud
brown aud red with green.
Among number of possible sources or
influences upon color vision, Or. Wilson
meni'ous the yeiioO spot Oh the retina, and
The coiors OF the choroid. Soemmering dis.
covered this spot; it is found only in the
human retna, that Of apes, and some liz
, ards The true character OF this spo; and
lis use, IS unknown. 1t has properties diff.
tcrent :rom every other part Of the retina,
aud IS the spot OF most distinct vision.
The cerebral theory of color-that OF the
prohoiogists, is stated to be dsavowed by
all natural philosophers. The cause OF color
Ohndness-whether in the coating of the
eye OF IN the nerves, no one can tell at pres.
/ ent There are just rs great differences in
tue senses OF taste, smelling, hearing, and
feeling IN persons, as in distinguishing
coIors. One person can distinguish musi.
cal notes correctly aud another cannot, and
we may never know the reason. 1t is
enough Tor The present 10 know that color
blindness does exist, and that il is more
prevalent than was supposed, in order for
Us to direct attention to it, for the reasons
already gwen .Setentfc american.