Chapter C: Francis Jenkins

1519 CONN AVENUE NW WASHINGTON DC

SOCIETY MOTION PICTURE ENGINEERS REGRETS
YOUR ABSENCE FROM THE CONVENTION
BEST WISHES FOR YOUR SUCCESS IN RADIO
TRANSMISSION OF PICTURES

A R DENNINGTON SECY

225P

GENERAL ELECTRIC COMPANY

In Reply Refer to

WEST LYNN, MASS.

November 28, 1922.

Mr. C. Francis Jenkins,
1519 Connecticut Ave.,
Washington, D.C.

Dear Mr. Jenkins:

I am in receipt of yours of
November 25th, enclosing the radio picture,
for which I thank you. It certainly
shows a successful result.

When I first read of your prismatic
ring arrangement in the “Scientific
American”, I recognized that it
was the solution of a problem which I
had often thought of as possible, and
I can well understand that it may have
applications which we do not even now
think of. It is perfectly possible, as
you say, to employ the method of radio
transmission of pictures on a very considerable
scale, which would hardly be
possible in transmitting them by the
ordinary telegraph.

With best regards, and gratification
to know that you are progressing,
I am,

Very truly yours,

Elihu Thomson

THE WHITE HOUSE

WASHINGTON

December 5, 1922.

Dear Mr. Jenkins:

Please accept my thanks for the
radio photograph which you were good
enough to send to me. The production
of a picture in this fashion is certainly
one of the marvels of our time
and I am under obligation to you for
sending me this handsomely mounted
copy which will be preserved as a very
much prized souvenir.

Gratefully yours,

Warren G Harding

Mr. C. Francis Jenkins
1519 Connecticut Avenue,
Washington, D.C.

Westinghouse Electric
& Manufacturing Company
East Pittsburgh, Pa.

Mr. C. Francis Jenkins,
1519 Connecticut Ave.,
Washington, D.C.

March 7, 1923.

My dear Jenkins:

I have been reading with much
interest the newspapers giving an
account of your success in sending
photographs by Radio from Washington
to Philadelphia. After my visit to
your laboratory a few weeks ago when
you told me of this proposed transmission,
I have been looking forward
to it feeling assured it would be
fully as successful as the papers have
related, and I want to add my congratulations
to the many you must have already
received, and which you so well
deserve. May your success continue.

With kindest regards, I am,

Yours very sincerely,

John

THE FRANKLIN INSTITUTE
OF THE STATE OF PENNSYLVANIA
PHILADELPHIA

March 8, 1923.

Mr. Francis Jenkins,
5502 Sixteenth Street,N.W.,
Washington, D.C.

My dear Mr. Jenkins:

I want to say to you how
delighted I was to receive your letter of
March 6th, accompanied by the beautiful
examples of your success in transmitting
photographs by radio. I enjoyed very decidedly
the opportunity that you gave me
of seeing the process of receiving these
pictures and have found since that a number
of those whose attention I called to
your work, took advantage of the opportunity
and were greatly pleased with the
results.

I can only say that I
appreciate to a certain extent, at least,
the tremendous energy and persistence that
you have put into the development of this
new art and most heartily congratulate you
on the success that you have obtained.

I am promising myself
that if I come to Washington at any time
in the near future to make a visit to your
laboratory and see you in your own private
lair. Hoping that such an opportunity
will not be too long delayed. I am,

Sincerely yours,

Geo. A. Hoadley.

S. and A. Assistant.

CHARLES FRANCIS JENKINS
232 SOUTH 7^{TH} STREET
PHILADELPHIA, PENNA.

March 12th, 1923.

Charles Francis Jenkins,
Washington, D.C.

Dear Friend:

The receipt of the Journal of
the English Historical Society a few days
ago, in which is given a list of Friends
who have achieved distinction through inventions
and in which your name is given,
shows that we have another point of contact
in addition to our exactly similar
names, and that is, we are both Members
of the Society of Friends.

If you ever get to Philadelphia,
I hope you will stop in and see me and
arrange to have lunch with me, if possible.

I have been much interested in
the considerable amount of publicity
given your work lately and I enclose a
page from the Evening Bulletin, although
I think it more than likely you have seen
it.

With best wishes,

Very truly,

Charles Francis Jenkins

NAVAL RESEARCH LABORATORY

“BELLEVUE,” ANACOSTIA, D. C.

21 August 1923.

Mr. C. F. Jenkins,
1519 Connecticut Ave.,
Washington, D.C.

My dear Jenkins:

Thanks very much for the samples of your
recent work. They look very good. I was
particularly interested in what you said
concerning the Chinese and Japanese methods
of transmitting telegraphy. I had heard
something of this before but never realized
how complicated it would make the process
for them.

As soon as I can get this laboratory
well started I will certainly find time to
look in on you and I hope arrangements may
be made for continuing some cooperative
work with you. We have designated a section
of our organization to work on
methods of secret communication but just
now we are unable to put anyone on that
work.

I hope you will keep me in touch with
your developments and let me know in particular
what progress you are making towards
high speed work. One of the best
arguments that I can make for the Navy
taking up such work will be the matter of
saving time in handling coded messages.

With best regards, I am,

Very truly yours,

A. Hoyt Taylor

Physicist, USN

POPULAR RADIO
9 EAST 40^{TH} STREET, NEW YORK

KENDALL BANNING, _Editor_ _Vanderbilt 9985_

September 11, 1923.

C. Francis Jenkins,Esq.,
1519 Connecticut Avenue,
Washington, D.C.

My dear Mr. Jenkins:

I certainly appreciate your interesting
letter of September 10th, as well
as the three photographic enclosures.
I am tremendously impressed, not only
with what you have accomplished in the
transmission of pictures by radio, but
also with the limitless possibilities
that you are opening up. It is entirely
conceivable that the work you are doing
right now may have an effect upon civilization
that will be almost revolutionary.

You must have had a corking good time
on your airplane trip from Omaha to
Chicago. Yes, we have been, undoubtedly
backward in the development of our airplane
commercial traffic. Some day we
will make up for lost time.

Cordially,

Kendall Banning

IMPERIAL JAPANESE NAVY

INSPECTORS’ OFFICE

ONE MADISON AVENUE

NEW YORK CITY

October 6, 1923.

Dr. C. Francis Jenkins,
Radio Pictures Corporation,
Washington, D.C.

Dear Dr. Jenkins:

Thank you for your kind
note of October 4th enclosing some
splendid reproductions of the message
I wrote when I called upon you at your
Laboratory.

Upon my return to Japan,
I shall inform our Home authorities
about the merits of your high
speed camera and radio apparatus and
will also present the fine samples you
sent me.

By the way, kindly
accept this expression of gratitude
for the courtesies you extended to me
and my associates during our recent
visit to Washington.

Very truly yours,

T. Kuroda

ENGINEER_CAPTAIN, I. J. N.

Commonwealth of Pennsylvania

Governor’s Office

HARRISBURG

October 23, 1923.

Mr. C. Francis Jenkins,
5502 Sixteenth Street,
Washington, D.C.

Dear Mr. Jenkins:

My heartiest thanks for your letter
of October 17th and for the copy of my first
photograph by radio. I appreciate it more than
I can easily say, and think it is a perfectly
marvelous piece of work under the circumstances.
Also it is more than pleasant to have it from
you, in view of our long association, and so
beautifully mounted.

With renewed appreciation, and heartiest
thanks for all the trouble you took in getting it
up.

Sincerely yours,

Gifford Pinchot

1339–1351 DIVERSEY PARKWAY

CHICAGO

December 21, 1923.

Mr. C. Francis Jenkins,
Radio Pictures Corporation,
Washington, D.C.

Dear Mr. Jenkins:

I was delighted to receive your letter
of the 19th. Heartiest congratulations
on making such wonderful progress
with the Radio Pictures. I am
sure that I am going to be one of
those fellows who can proudly say
“I knew him when—”.

With all good wishes for a Merry
Christmas and a Happy New Year, I am,

Sincerely,

Rothacker Film Mfg. Co.

W. R. Rothacker

WRR:GLD

EASTMAN KODAK COMPANY

ROCHESTER, N.Y.

February 18, 1924.

Mr. C. Francis Jenkins,
Washington, D.C.

Dear Mr. Jenkins:

I am in receipt of
your letter of February 6th enclosing
the copies of photographs sent by
radio. Your feat seems marvelous to
me and I heartily congratulate you
upon its accomplishment.

With kindest regards,
I am,

Sincerely yours,

Geo Eastman

W. J. Bryan'

WILLIAM JENNINGS BRYAN
VILLA SERENA
MIAMI, FLORIDA

July 29, 1924.

Mr. C. Francis Jenkins,
1519 Connecticut Avenue,
Washington, D.C.

Dear Mr. Jenkins:

I thank you for the Radio Photograph—it
is wonderful! What is
there left to be discovered?

Appreciating your friendly
interest, I am,

Very truly yours,

W. J. Bryan

Department of Commerce
OFFICE OF THE SECRETARY
WASHINGTON

February 1, 1924.

Mr. C. Francis Jenkins,
1519 Connecticut Avenue,
Washington, D.C.

Dear Mr. Jenkins:

I wish to express my
appreciation for the photograph which
you so kindly sent me. It represents
a very startling development in radio
and sometime when I have some leisure
I would be interested in discussing
the method with you.

Yours faithfully,

Herbert Hoover

CARL AKELEY
77TH STREET AND CENTRAL PARK WEST
NEW YORK CITY

March 16, 1925.

Dear Mr. Jenkins:

You are perfectly welcome
to publish anything I may have
written you.

I think few people
realize or appreciate the practical
possibilities of the transmission of
radio photographs and the high development
to which you have brought this
art. I congratulate you on your success
and wish a speedy realization of
your dreams.

Sincerely yours,

Carl Akeley

Mr. C. Francis Jenkins
Jenkins Laboratories
1519 Connecticut Avenue,
Washington D C

The First Radio Channel

While perhaps not singly applicable to the subject of pictures by radio, it is certain that without the discovery that signals could be transmitted through the air without wires, we should not now have either audible or visual radio.

While in 1832 Professor Joseph Henry discovered that electrical oscillations could be detected a considerable distance from the oscillator, it remained for a dentist, Dr. Mahlon Loomis, of Washington, D. C., to actually send the first radio messages. In 1865 he built an oscillating circuit, and connected it to a wire aerial supported in the air by a kite. One station was set up on the top of Bear Den Mountain, in Virginia, not very far from Washington; a duplicate station being set up on top of Catoctin Spur, some fifteen miles distant.

Messages were sent alternately from one station to the other station, by dot-and-dash interruption of a buzzer spark circuit; while reception was attained by deflecting a galvanometer needle at the station which was at the moment receiving.

In _Leslie’s Weekly_ (1868) Frank Leslie personally describes these “successful experiments in communication without the aid of wires.”

Later (1869) a bill was introduced in the U. S. Congress to incorporate the Loomis Aerial Telegraph Company (though nobody would buy the stock, and it remained for others, years later, to reap the reward of radio broadcasting).

In speaking on the bill, Senator Conger repeated, he said, the explanation that Dr. Loomis made to him, that—

This Illustration of Dr. Mahlon Loomis’s Wireless Telegraph Set Was
Made from His Original Drawings of His Invention Which Are on File
in the United States Patent Office at Washington.
]

“The system consists of causing electrical vibrations, or waves (from the kite wire aerial) to pass around the world, as upon the surface of some quiet lake into which a stone is cast one wave circlet follows another from the point of disturbance to the remotest shores; so that from any other mountain top upon the globe another conductor which shall receive the impressed vibrations may be connected to an inductor which will mark the duration of such vibration, and indicate by an agreed system of notation, convertible into human language, the message of the operator at the point of first disturbance.”—_From Congressional Globe, Library of Congress._

Perhaps it may be a coincidence, or perhaps a blood strain of the pioneer, that the first radio school ever set up by a woman should have been founded by his granddaughter, Miss Mary Texanna Loomis, Washington, D. C.

]

Nipkow and Sutton

One of the most interesting examples of the attempts to see by radio was made the subject of a patent by Nipkow in 1884. The proposed transmitter consisted of a selenium cell and an objective lens, with a spirally perforated disc rotating between the cell and lens “to dissect the scene.”

The receiving device employed the polarizing light valve used by Major George O. Squire, and Professor A. C. Crehore, to measure the flight of gun shells at Fort Monroe, Virginia, in 1895.

The Nipkow scheme was preceded by Shelford Bidwell’s device for “the telegraphic transmission of pictures of natural objects,” described in _Telegraphic Journal_ 1881, Vol. 9, page 83; and later almost exactly duplicated by M. Henri Sutton, and rather fully described in _Lumiere Electrique_, Vol. 38, page 538, 1890.

]

The Amstutz System

Of all the mechanisms which have been designed for the transmission of pictures electrically, that of N. S. Amstutz, of Valparaiso, Indiana, U. S. A., in the author’s opinion, stands out as the most conspicuous, not only for fine work, but for the cleverness of its accomplishment, the first successful picture being sent in May, 1891, over a 25-mile wire in eight minutes.

“Mr. Amstutz was not the first to send pictures over wire, but he was the first to send pictures with halftones, the others were simply line drawings. In this first method Mr. Amstutz used a relief photograph. The amount of relief was in direct proportion to the amount of light which had acted on the sensitive gelatine, resulting in an irregular surface, representing in elevation all the variations of light and shade in a regular picture.

“The picture received is actually a phonographic spiral around the receiving drum carrying the celluloid sheet. When finished it is removed from the cylinder and flattened out and a stereotype or electrotype made from it for relief printing; or the engraved celluloid sheet can be inked and printed immediately on the intaglio press.” (_From exhibit in U. S. National Museum._)

THIS PICTURE WAS TAKEN FROM
THE RECEIVING MACHINE AFTER
HAVING BEEN TRANSMITTED EIGHT
HUNDRED MILES OVER A TELEGRAPH
WIRE.

THE INTERNATIONAL
ELECTRO-GRAPH CO.

NOV. 1ST, 1900. CLEVELAND, O.

The Electrograph

From the accompanying illustration and title it will readily be seen that rather good pictures were reproduced with pen and ink method in 1890.

The original of this picture was given the author by Mr. T. A. Witherspoon, who at the time of the experiment (1900) was a principal examiner in the U. S. Patent Office, and detailed in charge of the Patent Office Exhibit at the Buffalo Exposition, where, also, these machines were on exhibition.

It may be a coincidence of passing interest that from Cleveland twenty-four years later the American Telephone and Telegraph Company sent their first wire pictures.

The Baker Machine

The machine of the opposite illustration, “the telestereograph,” is the invention of T. Thorn Baker, Esq., of England, and “was used by the _London Daily Mirror_ in July, 1909, and was worked by wire rather regularly between London and Paris, and London and Manchester.” The picture to be sent was “a halftone photograph printed in fish glue on lead foil, and wrapped on a sending cylinder, rotating once every two seconds with a metal point riding on it.”

The receiving cylinder carried “an absorbent paper impregnated with a colorless solution which turns black or brown when decomposed by the incoming electric current.”

What electrolytic solution was employed is not stated in the report, but was probably sodium iodide or potassium bromide judging from the description of its color and behavior.

To synchronize, the receiving drum turns faster than the sending drum, and is caught each revolution until the other catches up. (_Smithsonian Report_, 1910.)

2. FASHION PLATE TRANSMITTED BY PROFESSOR KORN’S
TELAUTOGRAPH.

The Dr. Korn Machine

The accompanying illustration shows the work of a machine developed by Dr. Korn, of Germany, and first used by the Daily Mirror between London and Paris in 1907. “On a revolving glass cylinder” a transparent picture was put. He used a Nernst lamp and “selenium cells on opposite sides of a Wheatstone bridge” to overcome the inherent lag of the selenium cell.

Signals were sent over a wire and received on photographic film on a cylinder, using “two fine silver strings free to move laterally in a strong magnetic field.” A light was focused on the obstructing “silver strings,” which the incoming electric signals, passing through the “strings,” separated to a greater or lesser degree “to widen or thin the photographed line.”

“When the film is developed it is laid out flat, and the spiral line becomes resolved into so many parallel lines.” The sending and the receiving machines were synchronized by “well calibrated clocks which released the cylinders at end of every five seconds.” (_Mr. Baker in Smithsonian Report_, 1910.)

]

Rignoux and Fournier Scheme

One of the early suggestions had for its fundamental principle a surface studded with thousands of “selenium cells” each a part of an individual circuit, and upon which a picture was projected. The idea was that the different cells would transmit a different value of current with each different intensity of light which made up the picture.

At the distant station a given surface had a corresponding number of tiny lamps, each attached to its respective cell at the sending station, and being lighted thereby the ensemble would reproduce the distant picture.

The scheme is possible but hardly practical, for if only fifty lines per inch each way were sufficient on a picture but one foot square, there would have to be three hundred and sixty thousand cells at the sending end, and a like number of lamps at the receiving end, each but one-fiftieth of an inch in diameter. Such a problem would seem to present difficulties, though the author himself in the bravery of ignorance suggested this very scheme in the _Electrical Engineer_, of July 25, 1894. (_Illustration by courtesy of Science and Invention._)

]

The Belin Machine

The “Belinograph” is the invention of Edouard Belin, of Paris. With these machines “the first step in transmitting a picture is to convert the latter into a bas-relief. Or a drawing can be made in a special ink, which, when dry, leaves the lines in relief. The picture when ready for transmission has an uneven surface, the irregularities of which correspond with the pictorial details. The transmitter resembles the cylinder of a phonograph. The picture is wrapped around this metal cylinder, and a style presses down on the picture cylinder as it is rotated by clockwork. As the style moves up and down over the irregularities of the picture, a microphone varies the strength of an electric transmitting current.

“At the receiving end another cylinder in a light-tight box carries a sensitized paper upon which a point of light is reflected from the mirror of a galvanometer actuated by the incoming current from the distant station.”

Two very accurately regulated chronometers are employed to keep the machines in synchronism, one chronometer for the sending machine and one for the distant receiving machine. (_From Review of Reviews_, 1922.)

]

American Telephone & Telegraph Company Machine

The picture opposite is one of those sent by the A. T. & T. Company on May 20, 1924, by wire from Cleveland to New York. Some of the pictures sent were from photographs taken earlier, and some were taken only a few minutes before being transmitted.

In the sending machine, “the film picture is inserted in the machine simply by rolling it up in a cylindrical form and slipped into the drum. During operation a very small and intense beam of light shines through the film upon a photo-electric cell within.”

In the receiving machine, “the sensitive film is put on a rotating cylinder and turns like the cylinder record on a phonograph. On this film falls a point of intense white light varied constantly.”

For synchronizing “two separate currents were sent over the wires, one is called the picture channel, the other the synchronizing channel.”

“Forty-four minutes elapsed from the time the picture was taken in Cleveland until it was reproduced in New York.” (_New York Times, May 20, 1924._)

It seems unlikely that returns from the daily wire transmission of pictures can equal the day-by-day revenue from the wires used for the transmission of speech when balanced up for the principal circuit, phantom circuits, and carrier circuits.

]

Radio Corporation Machine

The accompanying “photoradiogram” is a development by the Radio Corporation of America, and was transmitted from London to New York on November 30, 1924.

“The transparent picture film is placed on a glass cylinder. An incandescent lamp inside the cylinder is focused in a minute beam onto the film as the cylinder rotates, and this transfers the light values of the picture into electrical impulses, in a General Electric Company photo-electric cell.

“The receiving cylinder has white paper placed thereon, and the incoming dots-and-dashes, amplified in passing through a bank of vacuum tubes, are recorded in ink on this paper with a special vibrating fountain pen, drawn down by magnet coils to record the picture much in the style of an artistic stippled engraving.” The cylinders of both the sending and the receiving machines are “rotated back and forth, the electric camera itself advancing down the length of the picture one notch at a time.”

“The necessary synchronism of the two machines is maintained by the use of special driving motors, and a special controlling mechanism based on the constant pitch of a tuning fork.” (_See Radio News, February, 1925._)

By courtesy of “The World,” New York.

A RADIO CODED PHOTOGRAPH.

How the picture looked after being sent from Rome by radio and decoded
on Professor Korn’s machine.
]

The above is an example of one of the rather odd methods of “sending pictures by radio.” The picture to be sent is divided into many small squares with varying values of dark in the squares. Seventeen different grades of light in these squares are translated into seventeen letters printed on a tape.

This coded picture is transmitted to a distant place and there decoded into dots of sizes corresponding to the seventeen values, and each dot placed in its corresponding square on a white paper. The collection of large dots builds up the dark areas; a similar collection of smaller dots makes up the halftones; and still other collections of very minute dots make up the light areas. (_From the New York World._)

]

A telegraphic code scheme in which points in a picture are determined by the crossing of straight lines, ordinates and abscissas, and in which the shades of light, of gray, and of black which make up the picture are also indicated by letters.

This coded information is telegraphed to the distant stations where the receiving artist determines the location of these points and shades by (1) a similar pair of crossed straight lines, and (2) letters indicating the light values to be washed in on paper.

The process depends for its success largely on the skill and cleverness of the receiving artist, and is hardly more than a “filler-in” pending the adaption of the directly photographic process. (_Courtesy Science and Invention._)

]

The Braun Tube Receiver

One of the theoretically attractive forms of receivers is the Braun oscillograph tube, for it is so very easy to wobble the cathode ray spot about over the fluorescent screen, to form figures. It has an imponderable pencil of light which can be moved over the picture screen with very little electrical energy. Its use has been proposed by many.

But the feature of the system which is most often overlooked in this scheme is the necessity for an analytical picture machine at the sending station, and no such device in satisfactory workable form has yet been suggested.

The Braun tube system awaits, therefore, the attention of the practical-application engineer before it can compete with other forms of receivers.

]

Pictures by Radio in Natural Colors

It is well known that pictures in color are in common use in magazine printing, in window transparencies, decorations, etc. The process consisting in making three negatives, one through a red screen, a second through a green screen, and a third through a blue screen. When transparencies from these three negatives, each stained in its complementary color, red, green and blue, are superimposed and viewed by transmitted light, the resultant picture is seen in its natural colors.

With this process generally well known, it is obvious that three such negatives transmitted by radio or wire could be colored and combined to make a “picture sent by radio in natural colors.” Of course, the picture is not sent in color at all, and the author hesitates to claim for such a feat more than that the resultant picture proves the excellence of the synchronism of the machines employed in the transmission of the three successive pictures which after their reception are to be colored and combined into one.

]

Prismatic Disc Machines

These machines are principally used in radio transmission of photographs; employ four overlapping prismatic discs or “rings” in both the sending and the receiving machines. Either a transparent or an opaque picture is used in the sending instrument; and in the receiving camera a filament lamp, modulated by the incoming radio signals, recorded on a photographic negative plate.

In the sending machine (first illustration) the picture is projected with a magic lantern (1) through four overlapping prismatic rings, (2) two of which in rotation sweep the picture vertically across the light sensitive cell, at the same time the image is moved laterally by the other pair of prisms. The different light values of the picture are changed into electric values in light cell 4, and broadcast. A rotating perforated disc, (3) interposed between the lens and light cell, produces a pulsating direct current which can immediately be amplified through the usual radio transformers, on its way to the broadcasting set.

In the radio camera (second illustration) a photographic negative (1) is used and a pencil of light from lamp 2. The rotating plates (3) draw the lines and the radio signals vary the light intensities of the lamp to give gradations of exposure on the negative plate. (See next page.)

]

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The Jenkins Prismatic Ring

The prismatic ring or plate is a new contribution to optical science, and was designed for use in a machine for the transmission of radio pictures from a flat surface, and for recording them on a flat surface, the only way in which radio vision and radio movies will ever be produced; and a method which permits of the reception of portraits having true photographic value, without lines, and having tone and shading unequaled by any other known process to date.

The prismatic ring section is ground into the face of a glass disc, and from one end to a point half around it has its base outward, and from this midway point around to the other end having its base inward. The warp from one end to the other is gradual.

A beam of light passing through this ring, in rotation, is caused to oscillate, having its hinged action fulcrumed in the plane of rotation of the prism ring. The oscillation is always in the plane of the diameter of the disc from the point where the light passes through the prismatic ring section.

The plates (made with the initial grinding machine) may have one, two, or four prismatic sections to the ring, and may be made right or left hand, and in 10 inch and in 7 inch sizes, and also in disc ring (first illustration) or band ring form (second illustration).

]

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Jenkins Synchronizing Forks

The accompanying photographs show a vibrating-fork-control employed to keep distantly separated motors in synchronism. This is the motor control employed in the system developed by the author for the sending and receiving of photographs and photograms, by radio and by wire.

The control unit is surprisingly simple and dependable, and is believed might be found useful for many other purposes where it is desired to keep motors in step with each other which are separated by long distances, the control signals being sent by wire or by radio, and from fixed or moveable stations, on land, on water, or in the air.

The fork illustrated is about fifteen inches long, mounted on a cast brass frame with a bakelite cover plate upon which the fork, motor coil, and binding posts are mounted. A single cell of dry battery keeps the fork in vibration.

The device is designed on a new principle, and has a very sharp control of the motor revolutions. Simple means are provided for easily verifying the continuity of the motor control.

These fork motor units will control any number of motors of any size, at any distance, and on moveable or stationary platforms.

]

The Jenkins Picture-Strip Machine

In the transmission of news, market reports, etc., as a continuous process a long strip of paper of typewritten copy is put into this machine, and the blacks and whites of the letters and figures falling on the light sensitive cell open and close a C. W. broadcast or wire circuit; which at distant points is translated back into light and recorded on a long strip of photographic paper.

This can be a continuous process if the sending strip is added too from time to time, and the receiving photographic strip of paper, as it is exposed, passes continuously through a developing, fixing, washing and drying bath. This process might be required by the conditions of service. A white strip and an electric pen may be used instead of photo paper.

In the sending machine the rotating prisms sweep the image of the typewriter line across the light sensitive cell; and the strip is moved longitudinally by winding on a drum.

In the receiving machine the strip is drawn along while it is curved around a rotating cylinder inside which the modulating light is located, turned off and on by radio. A corona glow lamp is preferably employed with the photographic paper.

]

Jenkins Duplex Machine

The Jenkins duplex cylinder type of machine was designed for simultaneously sending and receiving photograms, letters, maps, drawings, etc. The motor runs all day long, like an electric fan, in control of the vibrating fork. The right hand (glass) cylinder sends; and the left hand cylinder receives. The messages are put on and taken off without stopping the machine, and without one function interfering with the other.

The machine may be used on radio or on wire, and is an easily operated machine, the perfect functioning of which can be determined by a glance at the perforated rotating disc illuminated by the synchronizing signal lamp.

It is believed to be the first duplex two-way service machine ever built, and is complete as shown, except for the batteries and the radio receiving set, which latter may be any standard set which will operate a loudspeaker.

The illustration shows a machine in which a picture transparency and a sensitive cell is used at the sending cylinder; and a high speed lamp and photographic paper at the receiving cylinder.

]

“Talking Machine” Photograms

The spring driven machine illustrated is probably the simplest device possible for the experimental study of transmission of pictures and picture messages by radio or by wire. A conducting ink or pencil line on paper and put on one cylinder (or an insulating coating cut through with a stylus) over which the sending point rides for sending; and an electrolytic bromide (or photo) paper on the other cylinder under the receiving pen for receiving; the contact points being attached to the sending and the receiving sets respectively.

The upper illustration shows a machine electrically driven and equipped to transmit and receive handwritings, maps, sketches, pictures, etc., of an area of about 5 × 7 inches. The sending is from pencil lines on paper, the reception on electrolytic paper.

The machine is also made with a glass cylinder to send from a picture transparency, and to receive on photographic paper. It must, therefore, be used in a dark or subdued lighted room to receive.

Each machine is capable of the very highest quality of work of its particular kind, and is simple and easy to operate.

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Radio Vision

The machines here shown are the laboratory models used in the development of Radio Vision and Radio Movies for the reception in the home of broadcast studio performances, i. e., dancing girls, public speakers, pantomime, marionettes, motion pictures; and, by remote control, outdoor events, sports, etc.

The lower illustration shows a 10″ disc rotating in front of a prismatic ring, synchronized by a variable speed of the motor. The light is in the round box at the top of the standard behind the lens carrier, and shines through lenses and prism (onto a picture screen) as they pass, the light fluctuating in value with the incoming radio signals to make up a complete picture every one-sixteenth of a second.

The upper illustrated mechanism differs from the lower one in that it has a second overlapping prism for optical correction.

The casing enclosing the mechanism is not very large, and contains, besides the radio vision mechanism, the radio receiving set, and a loudspeaker, so that an entire opera in both action and music may be received.

The prismatic ring can be rotated to follow any moving object; e.g., a
motion picture film; or if fitted with a high-reading automobile
speedometer the speed of an airplane or dirigible can be read
directly off a dial by the navigating officer.
]

]

glowing
filament
offset

hollow
cylinder
filled
with
light

NEW LIGHT
SOURCES FOR RADIO

vibrating
gold leaf
electroscope
for blinking
a constant
light
source

spark plug
light
source

]

The rotation of the disc _A_ carrying lenses _b_, _c_, _d_, etc.,
sweeps
the image of the light source _C_ across the screen _F_ in a
horizontal
direction, while line displacement in a vertical direction
is effected by reason of the changing angle of successive prism
elements.
]

The rotation of the disc _A_ carrying lenses arranged in a spiral
causes the light _L_ to sweep across the screen _M_. A revolution
every sixteenth second gives a motion picture screen effect.
]

RADIO MOTION PICTURE MECHANISM

The rotation of the drum _A_ carrying the lenses _b_, _b′_, _b″_,
etc., causes the image of the light source _S_ to sweep across the
screen _Y_ in two directions. A complete rotation every sixteenth of
a second is motion picture speed.
]

Radio Vision hook-up circuits. _A_ is the light cell. The upper
circuit puts a “chopper” frequency onto the radio carrier wave by
the inductive coupling.

The lower diagram shows an intermediate frequency oscillator to be
controlled by a light cell (not shown), the intermediate being put
on the carrier wave.
]

Historical Sketch of Jenkins Radio Photography

1894. Jenkins publishes article on transmission of pictures electrically with illustration of proposed apparatus.—_Electrical Engineer, July 25, 1894._

1913. Proposes another mechanism, for “Motion Pictures by Wireless.”—_Motion Picture News, September 27, 1913._

1920. Reads paper on the Prismatic Ring, a new contribution to optical science (an essential element in transmission of radio pictures).—_Transactions Society Motion Picture Engineers, Toronto Meeting, May, 1920._

1922. Sends first radio photograph; sent from a photograph, and received photographically; and predicts motion pictures by radio in the home.—_Washington Evening Star, May 19, 1922._

1922. Sends photographs by telephone wire of American Telephone & Telegraph Company, through his desk telephone, from 1519 Connecticut Avenue (Washington) to Navy Radio Station, NOF, at Anacostia, D. C., and there broadcast. The signals were picked up and recorded on a photographic plate at 5502 Sixteenth Street N.W., Washington, D. C., in presence of Commander A. Hoyt Taylor, of the U. S. Navy, and J. C. Edgerton, of the Post Office; October 3, 1922.

1922. Makes official demonstration of his radio transmission of photographs for Navy officials December 12, 1922, in presence of Admirals S. S. Robison and H. J. Ziegemeier, Captain J. T. Tompkins, Commander S. C. Hooper, Lt. Commanders E. H. Loftin and H. P. LeClair; the report of which was later released for publication.—_Washington Evening Star, January 14, 1923._

1923. Sends radio photographs of President Warren G. Harding, Secretary Herbert Hoover, Governor Gifford Pinchot, and others, from U. S. Navy Radio Station, NOF, Washington, to Evening Bulletin Building, Philadelphia, by courtesy of Robt. McLean, Jr., March 2, 1923.—Reproduced in the _Bulletin_, and in the _Washington Star_, March 3, 1923.

1923. Makes his first laboratory demonstration of Radio Vision (the instantaneous reproduction on a small picture screen of a distant performer or a distant scene), and of Radio Movies (the transmission of pictures from a theatre screen to a small screen in the home), June 14, 1923. See _Visitor’s Register_.

1924. Makes his first hundred-line photograph, June 15, 1924, portraits of true photographic values in which no lines appear. Photographs of President Calvin Coolidge, Dr. J. S. Montgomery, Chaplain of the House, William Jennings Bryan, etc. See letters of congratulations from subjects of these photographic tests.

1924. Sends message, in Japanese characters, from Charge d’Affairs, I. Yoshida, of the Japanese Embassy, Washington, i.e., sending from the old Navy Station, NOF, to Amrad Station, WGI, Medford Hillside, Massachusetts; reported and reproduced in _Boston Traveler_, December 4, 1924.

1924. Apparatus bought and used experimentally by U. S. Post Office Department, on night-flying section, Air Mail route, New York-San Francisco, first message night of December 3, 1924. See James W. Robinson’s telegram, December 15, 1924.

1925. Transmits Motion Pictures by Radio from standard motion picture film to be looked at directly on a small motion picture screen in the distant radio receiving set; Tuesday, March 31, 1925. S.L.A., F.M.A., J.N.O., J.W.R., T.P.D.

This machine is the prototype of the motion picture projector in
universal use the world over, the result of experimentation begun by
Mr. Jenkins in 1890; the machine finished and publicly exhibited in
1893 and 1894. Later shown before the Franklin Institute, and
thereafter in the U. S. National Museum. When it has completed its
service in the Laboratory office, the Franklin Institute Museum will
be the final depository.
]

The accompanying cuts show the Elliott Cresson Gold Medal, awarded by
the Franklin Institute, of Philadelphia, for a machine exhibited
before the Institute in 1895 by Mr. C. Francis Jenkins.
]

Later, in making a second award, that of the John Scott Medal, “in
recognition of the value of this invention,” the Institute Committee
said: “Eighteen years ago the applicant exhibited a commercial
motion picture projecting machine which he termed the ‘Plantoscope.’
This was recognized by the Institute and subsequently proved to be
the first successful form of projecting machine for the production
of life-size motion pictures from a narrow strip of film containing
successive phases of motion.”
]

ANNO DOMINI MDCCCCXXIV

In recognition of services
rendered to the screen by
=C. Francis Jenkins——=
as inventor of the motion
picture projector——

=S=tory =W=orld =M=agazine
of =H=ollywood, in a series of
articles published in 1923–24
names =M=r. =J=enkins as one of—
=T=he =T=en =G=reatest =F=igures in—
=M=otion =P=ictures—=I=t now takes
pleasure in making this formal
acknowledgment of its judgment—

=S=tory =W=orld——Jay Brien Chapman
September _First_ _Editor_

American Projection Society

INCORPORATED

ABILITY PROGRESS SCIENCE

MEMBERSHIP CERTIFICATE

This is to certify that