New-York tribune., 1922-05-07
Electron Gun
Shows Picture
Of Y ce
Wonderful Service Creates
Vivid Pictures of Voice
Vibration for Scicn-
fists to Study Problems
Was Developed Here
Action instantaneous and
Free From All Inertia:
Aids in Design Work

Have You over seen your own voice?
That sounds like a very foolish Que5-
ton to ask on radio page, doesn't it?
Well, despite its apparent absurdity
the question applies to very serious
matter, and one that has worry impor-
tant bearing upon the development of
radio telephony. Consequently it is
relevant on the radio page, a it also
affects broadcasting.
1t is possible to sec your voice, or
at least the oscillations caused by the
voice vibrations when electrically
transmitted and the story Of tho man
ncr in which this has been accom-
plishcd is one of the romanccs Of sci
cntifc achievement
At first glance it probably VIII cause
you to wonder why any one should
wish to see the vibrations Of his voice
and what good cause would be served
by making the vibrations visible. The
answer to this question is a very
simple one, and summed up is practi-
cally as folows
AIDS In Developing Apparatus
If it is possible to show exactly
what kind of vibrations various sounds
produce it viii then be possible to
determine just what their effect in an
electrical current Will be. This is very
important where such a sound as that
Of tho letter "s' is concerned because
of its confusion with the letter "fh and
also because it enables the scientists to
b,
apparatus that will give truer repro
duction of these difficult sounds.
1t has been possible for some time to
produce these vibrations by mechan-
lco electrical means used in coniunc-
ton with projecting machine whereby
the picture of the vibrations is repro
duce on screen, much in the manner
of movies" The trouble with this
system, however, is that there is a con
siderable lag behind the voice, due to
the inertia in the mechanical part of
the apparatu
The problem, therefore, was to pro
duce an apparatus that had practically
no inertia, and, as in many other kin
dred situations. the vacuum tube has
hiled the bill, In this case the vacuum
tube is quite different in appearance to
the ordinary tube, both in shape and
SO'iS|t uNN'Nil, anu II HilSIll DFllpl De
termed an electron gun, because that is
just exactly what it is. Moreover. it
performs its function of reproducing
osclllatory pictures Of sound and cleo
trlcal vibrations with absolute fidelity
and without inertia.
Tube Perfected Here
1t is known scientifically as the
Braun tube, named after the German
sci mt ct hn ECrf Il
real development has been made bv Dr..
j. B. johnson, of the Bell laboratories.
because it is he who has turned it into
really serVlceable instruments
1t is large, pearshaped tube, about
eight inches long and one inch in diam
eter at the socket end, which gradually
increases in diameter until at the
other end it is about four inches
across.
The end of the tube is covered with a
huorescent screen. A straight filament
about One-quarter of an inch in length
is used as a cathode, and four platinum
plates set at right angles to each other
guide the stream of electrons which
this cathode emts and directs them
upon the huorescent screen.
When the audio-freQuency or high
frequency currents are impress sed upon
Y
stream Of electrons which are fixed at
very fine point to move up and down
this screen with extreme rapidity, cor
responding exactly and with great pre-
cision to the fluctuations in the current
caused by voice sounds or other vibra-
tons.
Can Examine Voice Pictures
1t is possible to examine the huctua-
tlons produced on the fuoresc cent screen
very closely and to ascertain Just eX-
actly what kind Of vibration each par
ticular sound produces. In addition to
thu 1t is also possible to photograph
these vibrations. so that q. permanent
record can be made of any particular
sound that it is desired to study. and
those would give actual pictures of the
voice, which, of course. are extremely
valuable in designing receiving appara-
tus for reproducing such sounds.
The tube is very remarkable in
strument- especially as 1t has now
been developed. In addition to the
manner in which it reproduces all
sound variations visua!ly it also re