Charles Francis Jenkins
Francis Jenkins, (1867-1934) was born "in the country" just north of
Dayton, Ohio. He spent his boyhood on a farm near Richmond, Indiana. He Attended
a country school, a nearby high school and Earlham Collage. In 1890 he settled
in Washington, D.C. to serve as Secretary to Sumner Kimble of the U.S. Life Saving
Service. (This later became the U.S. Coast Guard). Five years later he resigned,
so he could spend his full time inventing. One of his first projects was a motion
picture projector, using a strip of sprocketed film. He built and patented an
operating prototype, the "Phantoscope" similar to those now found in
every movie theater in the world. (Note: It is commonly thought that Thomas Edison
invented the movie projector. This is not true.). His interest in motion pictures
was so great that in 1916, Mr. Jenkins went on to form the Society of Motion Picture
Engineers and was its first president. The Society is now the highly respected
"Society of Motion Picture and Television Engineers", a worldwide organization.
Mr. Jenkins also invented the spiral-wound waxed all-paper container, still in
regular use as a food container (ex: Pillsbury biscuits), mailing tubes and a
variation of the process to manufacture large shell casings for field artillery.
Even as a small boy, Mr. Jenkins was an avid reader of technical books and magazines.
Undoubtedly he read of some of the early principals of television and kept these
thoughts in mind, because in 1894, he wrote an article for the July 25 issue of
"Electrical Engineer" on the subject of transmitting pictures by wire.
It was a natural progression for him to go into television, which he called "Radiovision".
In 1921, along with a few well-chosen friends, he set up a research laboratory
in Washington D.C. to investigate the development and construction of practical
television transmitting and receiving apparatus. At first he needed to learn of
the techniques of scanning and his first venture would be the transmission of
still pictures by wireless. He successfully demonstrated this capability to the
Navy on December 12, 1922. This was called photo radio or facsimile radio. By
1924 he improved the apparatus by incorporating his prismatic rings scanner. This
provided received pictures without lines that looked much like a photograph. The
Jenkins prismatic rings, which provided a unique means of scanning, were originally
developed for a high-speed movie application. However they proved to be too costly
for use in Radiomovies.
By 1925, Mr,
Jenkins had progressed to Radiovision, Radiomovies and Television. He was sending
movies by radio from a standard moving picture machine to a small screen on a
radio receiver in another room in the Jenkins laboratory. On June 13, 1925, he
gave a successful Radiovision demonstration to the Navy with the transmitter in
Anatosia, at the Naval Laboratory station NOF and the receiver in the Jenkins
Laboratory. The receiver used a Nipkow disk equipped with lenses.
Up to this time, Mr. Jenkins had not made an effort to interest the general public
or at least the radio amateurs. He did not recognize the possibility of a monetary
benefit there. Potential sales to the Navy were a more immediate enticement for
him. At some point, he decided to install and operate a transmitter for Radiomovie
picture stories, with announcements describing the pictures. He applied to the
FRC (later became the FCC) and received approval to operate W3XK in the 46 meter
band. The first broadcast of radio movie picture stories was on July 2, 1928 with
a format of 48 lines and 15 pictures per second. The picture stories were silhouetted
adults and children doing common things. In announcements between stories, amateurs
were asked to write in and give their opinions of the show and tell how well the
pictures were received. Those that only heard the announcements because they had
no picture attachments, were urged add them to their receivers. Jenkins offered
the picture attachments such as disks, lamps, motors etc., at very low prices.
Many did buy what they needed and for those that wanted to layout their own scanning
disk, Mr. Jenkins was giving complete instructions via the broadcasts or by mail
when requested to do so. After a time, Jenkins began manufacturing a complete
low cost picture attachment and sold it below cost for $7.50 complete. Following
the first broadcast, the picture stories were broadcast every evening at 8:00
PM EST., except Sundays and holidays. Mr. Jenkins estimated his audience to be
between 18,000 and 20,000 "lookers-in".
To produce the silhouette films, Mr. Jenkins set up a special studio that allowed
him to make the silhouette films at very low cost. The adult actors were actually
laboratory staff, except for the children who were local kids from the neighborhood.
The silhouettes were
very popular with the "lookers-in". One was "The Old Dutch Girl"
of a cleanser advertisement. Transmitting only a large picture of the Dutch cleanser
can, clearly showed the possibility of television commercials. At one point, he
considered doing a commercial for Campbell's Soup in this way. Other silhouettes
included "The Little Girl Bouncing a Ball", "The Washwoman",
"Two Girls on a Seesaw" and another girl jumping rope, then putting
it away and turning somersaults.
only were sent because due to some bad information given to Mr. Jenkins by his
chief engineer, he was led to believe that producing various image shades
would require more bandwidth than the legal 5Khz available. Later, the FRC did
authorize him to use a 100 kHz band from 4.9 to 5.0Mhz. To take advantage of the
added bandwidth, Mr. Jenkins developed and produced a new 60-line lens disk model
with a companion receiver. A pair of these is on display at the Wayne County Museum
in Richmond, Indiana.
In 1929, the Jenkins
Television Corporation (of New Jersey) became a subsidiary of the Deforest Company,
who took control of all devices developed by the Jenkins Laboratories as well
as its merchandising. Mr. Jenkins was named a Vice-President and retained control
of the Jenkins Laboratories in Washington D.C. until 1930, when he resigned. He
resigned partly because of ill health at the time and mostly because he was no
longer in control and those that were would not cooperate with him. They felt
that they had a "white elephant" on their hands.
A few important elements of Mr. Jenkins early apparatus deserve a fuller description
so one may better appreciate his work as an inventor. Two of these relate to mechanical
scanners for television receivers. The problem to be solved was that the image
size obtainable with the Nipkow disk was very small for a given size disk. For
example, 2 foot diameter disk for a 48 line picture would provide an image about
1.5" square. The cabinet necessary to house this 24" disk would be quite
large, so a more compact scanning system would be desirable. Mr. Jenkins developed
two mechanisms to accomplish this. The first
one used a drum about 8" in diameter with four spirals of holes. In the center
of this drum was a metal tube, also containing four spirals of holes, rotating
with the drum and around a fixed special four element neon lamp. Between each
hole in the center tube, there was a quartz or glass rod to pass light from that
hole to an appropriate hole in the outer drum. A motor drove the drum at 3600
RPM and through a gear reduction, a commutator that selected one of the four lamp
elements in a repeating sequence at 900 RPM. The picture appearing on the drum
was over 2" square. It would have required a 36" scanning disk to equal
this. This model was built and demonstrated successfully, but the lamp life was
short and a less expensive overall design was desired. A six-spiral model with
a similar drum had also been considered. It would have provided an even larger
picture. This design was also abandoned for the same reason as the first. The
second model used a similar four spiral drum but with no center tube, commutator
rods. It also used a low cost standard large plate neon lamp.
addition to the drum, there was now a selector shutter that as it rotated, allowed
only one spiral on the drum to be active at a time and pass picture information
to the viewer. The motor drove the drum at 3600 RPM and through a reduction gear,
the selector shutter at 300 RPM. Both of these mechanisms required a much smaller
motor than might have been necessary with a 36" disk. This second model was
placed on the market and sold to the public.
Mr. Jenkins was also manufacturing professional scanning disk television cameras
and accessories. Many were sold to technical schools for training purposes and
broadcast stations throughout the United States.
In 1931, it was reported
that Mr. Jenkins was very seriously ill. His illness lingered and some three years
later he passed away. He had led a very productive life. All together, he held
over 400 patents, some 72 of which related directly to Radiovision, Radiomovies
Mr. Jenkins had a sign
in his office that he lived by. It said this: "If a thing is difficult; it
is as good as accomplished. If it is impossible, it will take a little bit of