Evening star., 1936-04-19

johnson trying to get the kinks out of
his overstrained pitching wing at a
hospital clinic eight States to the
westward.
Radio fans have been muttering
about strange noises for good many
months. 1t disturbed their programs
as we'll as their peace Of mind. But
that was nothing compared to the
companies doing a commercial busi-
ness via radiotelephone, especially
when they began having trouble get
ting their messages through these
clouds of raucous rumblings.
The groundwork is being laid now
to end the interference that the new
electric physiotherapeutic apparatus
used by doctors and hospitals is Great
ing, but only start has been made.
All the while scientists and engineers
have been searching the heavens for
what they call The Shadow and
Celestial Invasions" and the malice
of anti-social cranks."
THEY'RE funny, these tricky noises.
Although only using the same
Juice that lights your n1aZdas, the
signals will travel long distances and
even will span oceans. Sometimes
they aim straight for the sky and skip
around bit until they take notion
to pounce upon annoyed radio signals
a thousand or more miles away.
1t was only recently that the SCI
entists traced the noise to its lair.
Imagine their surprise when the lair
happened to be almost next door, in
one instance That happened at Cruft
Laboratory, Harvary University. where
Prof Harry Rowe Minno, with the aid
of direction finders and cathode ray
oscillographs and such complicated
devices, discovered that a radio ther-
apy outfit right on the Harvard cam
pus was the cause of lot of the queer
cackling that was drenching the wave
lengths.
That discovery threw the first light
on The Shadow" Prof. Mimic ar
ranged for the diathermy apparatus
to be operataed so that it sent out
signals in radio code. The machine
had no antenna, but the radio fire.
quency it generated was fed back
into power wires and the alternating
current supply system acted as an
antenna.
The signals were heard, sure enough.
Naval wireless operators picked them
up in Washington, Norfolk and the
Great Lakes. Here at last was the
cause of noise that had interfered with
commercial and amateur stations and
even had messed up some of the sig
mails broadcast during the stratosphere
balloon flight last Autumn.
How to stop the interference Is
the problem. The Federal Com
munications Commission has had its
monitoring stations and inspectors
tracing the diathermy signals. but
the F. c. c. isn't so sure that there
is anything it can do about the sit
uation except perhaps to organize q
publicity campaign.
Meanwhile, doctors are buying radio
diathermy machines by the hundreds.
They are used in treating a flock of
aches and pains and are more con-
venient than the older diathermy ap-
paratus because the therapeutic rays
can be directed right through cloth
ing to the part of the body that is
being treated. This saves the doctors
time and trouble and makes it un-
necessary for patients to disrobe. The
makers of the machine all have their
favorite wave lengths, generally rang
ing from l6 to so meters, or about
5000 to 10000 kilocycles.
The conservative American
Medical Journal, in a recent issue, rec
ognized the evils of radio diathermy,
from the communications standpoint,
probably at the suggestion of the F.
c. C. The Journal first pointed out
that the American Medical Associa-
tion's council on physical therapy
does not accept the claims that one
wave length is more efficient than an
other. Then it suggested that the
manufacturers get together and pick
out a particular wave length, which
then could be designed for thera-
peutic purposes. In the meantime,
it went on, users of the apparatus
should consult the makers about the
methods of preventing interfering sig
nails.