Radio Broadcast - 1925, February - 113 Pages ... - VacuumTubeEra

forward.
66 4 Rg.dio Broadcast
THE
A
PROFESSOR AT COLUMBIA
physical equipment of the new department
was primitive. There was only
a temporary shed, a "cowshed" the students
called it, with a laboratory equipment of a
dynamo, a motor, and an alternator. 1 1 seemed
a hopeless prospect to the young teacher fresh
from the marvels of European science but his
enthusiasm was such as to conquer
all difficulties.
" From my studies of the experiments of the
European physicists,
1; concluded that
sound, like Ijght, traveled
by the vibrations
being carried from
one wave to the other,
reinforced by each
wavelength. believed
that by I shortening
the length of
the wave, the sound
could be carried further
and on this
basis I
perfected my
induction coil. By
using three or four
coils to the mile on a
Professor Pupin has not only cradled the art
of long-distance telephonic communication but
he is
responsible for six out of the nine basic
radio inventions. In 1895-6, while he was an
assistant professor at Columbia and working in
the derided "cowshed" laboratory, he evolved
an apparatus for electrical tuning and rectification,
and in 1902 he sold his patents to the
Marconi Company. This fact is not generally
remembered.
Professor Pupin, fresh from his European
studies, had become much interested in the
theories of Hertz, the father of radio, and had
begun experimenting with them. At that
time, the rectification electrical transmission of
sound was not known, the waves brought an
indistinguishable buzz which Professor Pupin
hoped to make audible. After a year's experimenting,
he succeeded.
Sounds which the waves brought could nowbe
understood. But the growth of radio had
only just begun. Professor -Pupin, who nurtured
radio in its infancy, brought it still
another step
.
He suggested .modifications
which transformed these explosive
electrical motions into more or less ^damped
oscillations.
All of us know to-day that when our
wavelength.
receiver is not in resonance with some particular
transmitter,
we simply turn a
knob to get the desired
But in the 1890'$
tuning- wasn't so simple.
In fact, troublesome
wavelengths
were one of the biggest
drawbacks -to
the science. Professor
>Pupin undertook
to correct, this de-
Through
ficiency.
e x h a u s t i ve experiments,
he devised
an ^apparatus which
long-distance telephone
sup-erimposed these
wire, the size
waves and got them
of the wire could be
phase.
considerably reduced.
PROF. M. I. PUPIN
"The electrical tuning
Not long ago, a friend
1883 when he graduated
of mine, a from Columbia receiving
University
telephone
end, as we know it.
executive, figured
came into use when
that my invention had saved the telephone Marconi took over my invention of electrical
company about a hundred million dollars and tuning," Professor Pupin explains. "Selectivity
went on to say that without it
long-distance was thus introduced into wireless reception and
communication could never have been greater
it eliminated some of the objections to the new
than about twelve miles."
form of electrical communication. Rectification
of the received electrical oscillations by.
crystals of asymmetrical conductivity, or by
my balanced electrolytic rectifier was the next
advance."
A TEACHER OF FAMOUS MEN
has started
AS, A teacher, Professor Pupin
many of our most famous radio figures on
their triumphant way. At one time three boys
were working under him for their doctor's
degrees. They were E. H. Armstrong, 'J.
H. Morecroft, now of Columbia University,
and Alfred N. Goldsmith of the College of
the City of New York. It was in Professor
Pupin's laboratory at Columbia that Armstrong
successfully developed his feed back circuits.
It was in Professor Pupin's laboratory