Evening star., 1928-09-23
TELL HOW TO SEND
/ PICTURES BY WIRE
Likeness Should be Clear for
Photo TeIegraphic
Dispatch.
BY HOWARD w. BLAKESLEE.
Associate Press Science Editor.


NEW YORK (P).-How good is YOU
photo-telegraph signature-and what il
the best way to send your photo
telegraph face to a friend?
These are questions which have beer
taken out of the research laboratorie;
and laid on the public's show case, now
that either messages or pictures may be
filed at telegraph offices for wire trans
mission. The answers given here have
been gathered from the photo-trans-
mission laboratories of the telephone
and telegraph companies which are
doing this work.
Some Not So Good.
If your signature is done in big
masterful fist" 1t is not altogether
good for photo transmission. The big
signature can be sent just as readily a.
any other, but not without cutting out
some of the space available for other
information in the same message. For
the photo-telegram is limited to what
may be set down clearly on a S by
Finch photo. That is much when type
written, but many sample of chirog-
faphy would not do so well.
For your o-telegraphic face. il
your purpose is to give very clear
idea of your appearance, the file should
be closeup, preferably with the lights
and shadows we'll defined, that is, not
too much of the twilight effect. But if
some necessity compels sending your
face when you do not care about having
its details too distinct, then file pic
ture which has plenty of background,
such as relatives, friends or trees or
group photos, and be sure to specify
that the background be included in the
wire transmission.
This again is all because at the pres
ent stage Of development by z is the
largest size transmissible, and the mov-
ing finger of light which paints this
wire picture can do wonders with large
figures close up, but not so much with
details that are too small.
How Photo Is Sent.
Two fingers of light. one in the send
ing city and one in the receiving city,
with an electric current between them
do the photogram work. An ordinary
photo is first made of the message or
picture to be sent. This photo is de-
Veloped on transparent cellulo!d him.
which is rolled into cylindrical form
about the size of an old-faShloned
volved, with tiny beam of light. one
one-hundredth of an inch square. shin
ing through it. The needle of. light
passes over the cylindrical film until il
has scanned every part of the surface.
This beam is bright or dark after
It penetrates the film, according to the
objects in the picture. A photo-electrtc
cell catches the varying light, changes
it into an electric current, the current is
then amplified about 16 times, and
transmitted by wire to the receiving
city. There another tiny light finger
scans another cylinder, but this time
the cylinder is an unexposed photo
graphic film. The receiving light passes
through a small aperture which Is
opened or closed by ribbon. This
ribbon receives the electric impulses
from the machine in the sending city,
and they cause it to vibrate. The Vi
bration permits light to pass through
the aperture and fall upon the unex-
posed negative in the exact proportion
of the light from the original picture,
which is thereby reproduced.