The Washington times., 1922-01-22

THE Mechanical Detector,", the de
tective Machine" has been the
theme of novelists for many
years. lZz
At last science has caught up with the
fiction writer's, and Professor Knight Dun
lap, Professor OF Psychology in Johns
Hopkins University, Baltimore, has in.
vented a machine which points finger
with unerring accuracy at the guilty one.
1t is a mechanical detective which
works upon scientific lines and is based
upon well-known principle of the work
ings Of the human mind.
Briefly and rather crudely, the thing
may be illustrated and explained by say.
ing that certain words are associated with
certain ideas in the minds OF individuals.
For instance, If you show piece Of can
vas to a sailor, he thinks of sail. Show
a bottle to a bartender and he thinks OF
something to drink.
But IL you show a piece of canvas to
an awning maker he will not associate 1t
with a ships sail. Nor does bottle
mean "a drink" to perfumery maker or
a druggists clerk.
The scientific detective machine Is built
upon the very we'll recognized fact that
uppermost in the human mind are always
floating ideas relating to whatever may be
the chief anxiety or interest of the indi-
vidual at the moment. II you can get the
key word to catch the floating thought you
can penetrate through the secretive shell
Of the persons exterior.
The murderer is thinking. perhaps sub.
consciously, of his murder. Floating on
the thiefs mind is his robbery and
his fear Of detection in connection ~
Herewith. 81
The new scientific crime detector is
specially baited to hook the betraying
thought. Because it is machine, 1t
operates in a passionless way without pre-
judice for or against a suspected person
For the same reason, 1t is absolutely ruth
less.
Professor Dunlap says that It will take
the place of the third degree" in the ex-
animation of persons suspected Of crime.
The machine, to look at 1t, seems
rather simple affair. 1t has dial, around
which spins a sort iof clock hand. The
only other conspicuous features are two
disks of thin celluloid mounted on tripods
The whole apparatus Is set upon an ordi
nary table.
A small electric motor behind the dial
makes the clock hand spin around. But
the clock hand does not move unless one
of the celluloid disks is vibrated.
M nv anaakfna
the clock hand In motion. A word spoken
in like fashion by another person close to
the other disk instantly stops the clock
hand. In either case the sound vibration
produced by the voice actuates the mech
anism.
The clocx-hand makes five revolutions
per second. The face OF the dial has 100
divisions. Thus each division represents
1-500th Of a second,
II will thus be understood that the ma
chine is able to record with utmost &C.
curacy the time that elapses between the
speaking Of word by one person and the
utterance of a reply by second person.
An index plate at the top of the dial
shows the number Of revolutions made
by the clock-hand. Suppose II shows an
s, and the hand has stopped at the so
point. This means that the hand has
travelled $50 divisions during the time
elapsed between the speaking of a word
and the utterance of q reply. Each di.
vidual at the moment IL you can get the
the elapsed time is a trifle short of
second and three-quarters.
So much for the mechanism. Now let