The morning news. [volume] (Savannah, Ga.) 1887-1900, 1893-10-29

Another test Of n quick perceptive fac
ulty lies in ones ability to correctly lndi-
cate by pencil mark the number of SINH
lar printed characters in sheet contain
ing 2l5 characters resembling each other
Just enough to make one hestutea moment
and refer to a guide line AZ the top of the
sheet. The percentage is quickly de-
termined by placing over the marked
sheet skeleton from which the correct
figures, as they appear at different places,
have been cut out.
A somewhat similar test consists in
looking at a series Of circles very slightly
open at different positions, some at the
top, others at the bottom or side. and re-
producing them as nearly as possible from
memory.
Quickness and accuracy of eyesight are
tested by a special apparatus, and are
used in connection with special training
which usually precedes sparring matches
and like tstic recitals.
At this point the examination runs into
a color test, in which is used large black
disk containing twentY-eight patches Of
color consecutively numbered In the
center of the disk is a circularopening A
smaller disk underneath shows the same
colors lettered instead of numbered.
If the subject of the test is color blind
he will be very apt TO insist that a. on
one wheel matches with % on the other.
The first is a very pronounced green, and
the other a subdued gray.
In the matter of determining colors
women make a better average than men.
The department has no figures on aver
ages, but all the colors have been fire.
quently correctly matched in one minute.
The central idea of the fourth group is
to measure the quickness of the mental
process The right hand is placed over a
telegraph key. As soon after the left hand
is touched with any substance as the sub
ject can determine the sensation he strikes
the key with the forefnger of his right
hand
The time necessary for the nervous i'm
pulse to travel up the right arm, an
nounce itself to the brain and be in turn
transmitted down the left arm, averages
1900 of a second
Ear perceptions, or reactions, are taken
by striking bell while dropped shutter
furnishes a similar test for the eyes.
Time in these instances is measured by
the distance through which a hand has
turned, and its amount is read off directly
from graduations on dial in hundredths
of a second.
The next test is Of the combined facul-
ties of memory and association, the object
being to secure pure sense memory. A
straight line is drawn, as at the beginning
of the test, and after a lapse Of about two
minutes the subject reproduces itas nearly
as possible
The memory span, or extent of memory,
is determined by the number of words
one is able to recall after reading them as
they appear for a moment In an opening
behind which a printed list of words
passes There are nine words in the
series and the average man can remember
but five or six of them.
A lBrge number Of curious and interest
ing instruments which are not brought
| into requisition in tine tests conducted at
| the fair are shown in cases in one of the
rooms.
There is perimeter by which the sen
| sibility to form and color in different por
| tions of the retina is mapped out. The
| subject looks with one eye at brass but
ton termed a fxation point. While star
| ing at this point he attends in indirect
vision TO a pair of points or patch of color
| held in a slide.
| BY q. movement Of rack and pinion this
| test object is moved along the arm, and
| the arm itself moves about the central
| point In this way all the meridians OF
| the eye may be examined, and the result
| automatically registered.
| A photometer is used in studying the
| sensibility to intensities of light.
There are innumerable tests for the
| color sense. One is series Of wheels
| with attachments for changing the pro
| portion of colOrs while the disk is in
motion For the same purpose a set OF
| ground glasses covering c0lored ones are
| used.
Another test for color blindness is a
| series of black letters printed on colored
! paper. When these are covered with It's
| sue paper only the complimentary color
| shows. The person afflicted with color
! blindness cannot see these letters, al
though they are distinct to the normal
| eye.
One of the most ingenious piece of mech
! anism is for testing the sense Of hearing
and for determining the appreciation OF
| the difference in musical pitch. The
sound is produced in a closed organ pipe
the pitch Of which is varied by changing
| its length.
An automatic arrangement is adopted
! by which the sound is continued during
one second, then there is silence during
another second, then sound is produced
! during a third second. During the inter
| val OF silence the length of the organ pipe
/ admits of being varied by known
/ amount. The instrument is used in this
| manner:
A scale is adjusted to fix the amount oil
! movement that can be given to the sliding
| plug in the organ pipe This will allow
| two notes to be sounded, differing by any
number of hundredths of a semitone.
If a person to be tested can, after sew
eral trials, distinguish the notes either By
saying that they differ or by knowing
which is the sharper, the interval between
| the two notes is reduced