The Redwood gazette. [volume] (Redwood Falls, Minn.) 1873-1940, 1878-04-25

approximate very closely to 10 per cent,
and Is certainly an element of sufficient
Importance to demand recognition and
investigation in all cases where the
preservation Of life and protection of
property depend upon correct and per-
beet vision.
The first defect in this connection to
which our attention would be directed
as having . practical application to
railway service is that known as color.
blindness. This defect but rarely as
sumes the form that would be termed
absolute color-blindness or want of anu
sensation of color. Where this form Is
perfectly developed there is generally q
sharp, well-defned appreciation of diff
ferences between light and shade, or
even between the finest grades of APP
parent brightness or intensity; but
recognition Of color is entirely want
ing; there being no distinction what
ever between different colors having
the same degree of intensity. A curl
GUS fact might be noticed in this connec-
ton that these defects are but rarely
found in women.
The more common form is that.
caused by the absence of perception of
one of the three fundamental colors.
These are mentioned in the order of
their comparative frequency, viz:
where the elementary sensation CORE
spending to red is wanting; next, the
absence or imperfect perception of
green, and third of blue is excluded.
It will be noticed as remarkable fact
that the first two mentioned are now
used to make up the entire code of rail-
way signals, and that this defect for
red occurs more frequently than for
any other color. This is an item of
the greatest importance in railway and
vessel management, since red is almost
always used for the danger signal. To
add still further to the deceptive and
dangerous character of the defects,
have, in the course Of my experiments,
found a number of persons who were
unable to distinguish between the pri-
mary colors at night, while their per-
ception or sensation of color by day.
light was apparently perfect. Again l
have found another anomaly which, un-
til it has been more thoroughly inves-
| tigated and the real causes that pro-
dhce it are understood, I shall desig-
nate as form of blindness, al
though I am in doubt myself as to its
dependence upon any of the principles
that enter into that defect; this is an
inability to distinguish between or to
recognize the primary colors at certain
distances. varying more or less in in
dividuals. This was found to be the
most difficult of all defects to detect in
the various cases I have examined,
amounting to some nine or ten, in the
regular course of my business as opti-
clan during the past three years. ]
have found no two of them at all alike
except in general results.
have kept records Of various acct
dents that have occurred, both upon
land and water during the past few
years, and I have gathered such infor-
nation about some of them as could
get outside of official sOurces-Often
was unable to get any of any value, but
I am convinced beyond doubt that q
/
been traced to this defect for correct
solution as to the primary causes of the
accident. The query has been made,
that if these defects in their various
forms are as numerous and of such 9
dangerous character as has been shown,
how can we account for such a com.
paratively small number of accidents
occurring which might be charged to
them? 1have attributed it to the high
average intelligence and acquired eau.
tiousness of engineers and pilots as a
class. They have become SO accus.
toned to be on the lookout for danger
that their suspicious are easily aroused,
which creates sort of instinct that
governs their actions and they do no,
recognize but that their perceptions are
correct. My convictions in this respect
have been greatly strengthened within
the past few months, there having been
related to me some experience with an
engineer who was continually making
narrow escapes, and after watching his
actions under different circumstance
for a time, color blindness was suspect
Cd, proved and afterward acknowledged
by him. The correctness with which
he formed conclusions under the exist
ing circumstances would indicate tina,
he had some means by which he wal
enabled to form plan of action, bu
he declared that he had nothing upor
which to base his actions but the eau
tiousness acquired in that branch o
service.
1t could be claimed that this illustra
ton lessened the importance of perfec
vision, and rendered it of no great con
sequence whether person was defect
i've in this particular or not, 50 long q
he formed judgment correctly. Thi!
might lie true # vision depended upor
judgment or instinct, but as we form
judgment in a large measure by com
parsons upon impressions received
through the medium of vision, it viii
be apparent to all that it will be impos
sible to form correct judgment whcI
the basis upon which it is formed il
imperfect. 1t is quite possible tina
such q person may continue to max,
narrow escapes, falling upon the sid
of safety each time; but as there ID NJ
natural law by which his judgment il
made positive and certain, the very
next occasion may Dy tne meres
chance result in serious error. Ii
investigating all of the different forms
of color blindness before mentioned,
have invariably taken into considera
ton the quickness of perception. Thi'
1 have found varied quite as much il
the different individuals and even IL
the same person ut different times a!
the defect has differed in form and de
gree. The correctness and quicknes.
with which Judgment is formed and
will power exercised after the percep
tions are received by the mind through
the medium of the senses depend in ,
great measure upon the physical condi
ton of the body. I have found tina
very slight physical or mental weari
ness produced results which showed ,
difference of between 80 and 80 PEI
cent. in the time consumed.