The Coolidge examiner., 1931-08-14
Machines That Are
Almost Human
The Invisible Policeman
BY E. C. TAYLOR r

D ECENTLY in New York city a
IN $50 bill was offered to any per
son who could pick it up without
causing an invisible policeman to
sound an alarm. No one got the
$50.
The invisible policeman on guard
was an unseen ray. 1t was set up
at a meeting of the New York IL
Eliminating Engineering society in
the Westinghouse Lamp company.
The bill was put in a five-foot
safe with the door closed but un-
| locked. Somewhere athwart the
safe, probably across the door, an
ultraviolet ray of light was placed.
The ray could not be seen. 1t
was harmless; it could not be felt
by the human touch.
The ray "shone' upon a photo
electric eye some distance away.
Anyone attempting to take the $50
| bill from the safe would interrupt
the ray, thereby casting an unseen
shadow" upOL the electric eye.
ThereupOn the eye would loudly
ring a burglar alarm.
with these rays" said Mr.. Nc
Coy, 1T is possible for jewelers.,
bankers and other custodians to
add greatly to the security of their
valuableS. 1t can be made impos-
sible for an intruder to move about
without detection, as the rays can
! be placed at various angles in a
room. They may operate a tear
gas barrage, or set off a silent alarm.
They can be projected far enough
to protect the entire mouth of
harbOr in war time with warn
ing signal belt"
! One of these invisible policemen
now stands at a gate in Spring
field, Mass, and counts autOmo-
biles as they pass on the adjoining
road. The robot has no physical
contact with the passing automO-
| biles. No wires stretch across the
road to fash a signal when a car
passes.
The unseen ray of light is used.
When an automobile passes, it
| breaks the ray, and the mechanism
within the robot adds another to
the total of the cars that have
passed.
This new black light" is being
used more and more extensively
to expose fraud. 1t can disclose
forgeries and counterfeit money. It
has been used even to trap bootleg
! gers. The makers of industrial al
cOhOl can put very small dose of
fluorescent dye in their alcohol, and
the dye will "shine" when the un-
seen ray is directed on 1t, no mat
ter how much the bootlegger had
Cooked" or otherwise tried to
disguise his product.
A new "fever tube" giving off
rays similar to this, developed in
! the radio research laboratory of
of the General Electric company at
Schenectady, N. Y, has aroused in
the mind of it's inventor, DR.. w. r.
Whitney, director of the labora-
tory, the thought that radio may
eventually be used to heat the
roomers instead of the room.
1t may be possible, he holds, by
using an adaptation Of the fever
tube to supply heat to the Occu-
| pants of homes and office buildings
instead of heating the homes or
buildings themselves. We heat
| thousands of cubic feet 0. space,
he says merely to keep the body
warm. Maintain sufficient heat In
the person instead of an excess of
steam in radiators.
Doctor Whitney's fever tube
sends off unseen rays of heat that
are absorbed by the body upon
which they are directed, but which
are not felt in the sense Of being
hot to the touch.
His suggestion is that his device
might be placed in the walls Of a
room, the rays directed across the
path of greatest activity, and then,
| with windows open, no furnace in
the cellar and no radiators to look
after, the inhabitants would be
comfortably warm.
Scientists are making wide use
of these unseen rays and variations
| OF it.
A weird light has been produced
that causes moving objects to slow
down or appear still. This light, re-
sembling a huge flash light, turned
on a whirling electric fan, caused
it to look as though the blades
were at rest.
Engineers have used this to find
out what caused erosion on the
tips of airplane propelIers during a
rain. The Eight" made it possible
to see the cracks forming in the
blades when artificial rain was
turned on when they were in mo-
ton, and this showed how to pro-
tect propellers against this.
| (0 1881 Western Newspaper Union)