The Washington herald., 1922-09-05
INVENTOR DISCUSSES METHOD
OF MAKING MOVIES BY RADIO
c. Francis Jenkins Addresses Large Gathering
at Central High School.

/
pictures by radio before a large
gathering at Centra. High School
on Thursday night. The technical
description of the process as given
by Mr.. Jenkins follows:
| At the top Of the stairs in the
Library of Congress. up on the Hill, is
a wonderful mosaic picture, a pic
ture made up of little stones in va
ried tints and shades. In general
1t is laid up in rows. which we may
| imagine beginning at the top and
going across from left to right in
parallel lines. as one would read
the page OF a book.
Now 1t would be entirely possible
| to take that great picture to pieces.
one little stone at a time. and mail
each little piece to Boston in sue
cessive separate envelopes, first
taking down and mailing each of
the stones of the first row. and
then of the second row. and so on
until the whole picture has been
taken to pieces and the pieces
mailed, each in a separate envelope
and each at a separate time.
And IL in Boston we had someone
who was instructed to reassemble
this picture, beginning in the left
hand upper corner and going across
to the right in the first row. then
the second, etc, each little stone
placed in the order of Its arrival,
| il would be entirely possible for
the artistic reassemble this great
picture in exact duplicate of the
original, SO that the stones which
made up the blacks of the pictures
would be in their places. as well as
the white stones which made up
the high lights, and the gray stones
which made up the half tones.
Now this is similar to the method
we employ in sending pictures-by-
radio except. Of course. that II 10
| done entirely with automatic ma
| chinery, that is, a machine in our
sending station covers the whole
| picture in lines beginning at the
| left-hand edge and at the upper
/ corner. and going across from left
| to right in successive adjacent
parallel lines until the whole pic
ture Is covered.
Every part of the picture then re-
fleets its particular strength Of
light onto a light-sensitive cell.
| Selenium Is the old standby for
such work. but the cells We use
seem preferable as they are much
more responsive.
| The new device which has made
possible photographs and motion
pictures-by radio is the prismatic
ring, a new optical shape in glass.
1.-THE action of which is to give to the
ray Of light along a fixed axis on
/ - -
or hinged axis on the other side OF
the prism.
It will be observed, therefore. that
IL this hinged end Of the pencil of
light travels across the picture from
left to right, that the other end of
the pencil OF light which lies in the
| fixed axis beyond the prismatic
rings will fall in the same place.
that is, on the light-sensitive cell,
This light-sensitive cell is in an
electric circuit. the current flow OF
which fiuctuates as the resistance of
| the cell changes with the different
! strengths of light impinging on it.
This fuctuating or modulated
electric current Is then impressed
| on a radio broadcasting set. direct
! ly. or after being amplified through
picture wave being impressed on
| the radio carrier wave.
Perhaps / might stop to explain
rather curious thing. and that is
that one of the processes we are
trying out converts the light values
| into sound values. which are ac-
tually put through the ordinary
carbon transmitter-that is, the
/ ~ - IN
phone. l can't say that this is the
best plan. but it is one which works
very satisfactorily. 1t does. how
ever, enable US to telephone a pic
ture to NOF (Anacostia Air Station)
and have 1t radioed back to us.
When these modulated electric
currents. coming into a receiving
station on the radio carrier wave,
are impressed on a suitable light
controlling device. for example, the
light from a little lamp changes in
light value to correspond exactly
to the current value of the modu-
lated radio carrier wave.
This fluctuating hight from the
lamp then passes through another
pair of prismatic rings, the furr-
tion of which in this case Is to dis
tribute this pencil of light over
Photographic negative in the same
order as 1t was sent-that Is, from
left to right in parallel contracting
lines until the whole surface of the
Photographic negative Is covered.
Now as the strength Of the light
coming from the little lamp fluctu-
ates in actinic value, obviously the
exposure of its image on the mega
tive has greater or less photo
graphic effect-that is. II the light
spot Is strong at any. particular
moment: we will have full time
exposure on that particular spot in
the plate; II the light is dimmed to
place where 1t has no photo
graphic effect on the plate. there is
an absence of any exposure at ALL
think 1t will be seen then. that
by causing this little lamp to fuc-
tuate in Photographic value as its
light falls on the plate at the re-
ceiving station. and that IL this
| fiuctuating light corresponds in
time and place and strength with
the different light values In the
original picture at the sending sta
tion. then we should get duplicate
| OF the picture when the plate Is de-
veloped, and this Is exactly what
happens.
To repeat, let me say that two
pencils of light, the one at the
sending station, are crossing their
receiving station, are crossing their
respective picture surfaces In ex-
| actly the same order and same
time, and that they correspond ex-
actly in light value. When there
are hiph lights In the pictura NJ fb~