C. Francis Jenkins

“ In commerce one may send letters, telegrams, bank drafts, or engineer’s drawings, as radio photographs of the originals, with photographic accuracy and autographic authenticity.
Men on the ground talk with men in a flying machine out of sight in the sky, an almost inconceivable fact. ”

“ When the machine of Radio Vision is turned over slowly, the little spot of light on the screen which makes up the picture looks for all the world like a tiny, twinkling star as it travels across the white surface of the screen in adjacent parallel lines, changing in light value to correspond in position and intensity to the light values of the scene before the lens at the broadcasting station. ”

“ But continuing the description of the still picture processes a little further, before taking up Radio Vision and Radio Movies, it might be added that while photographs by radio is the more interesting and impressive process, there is little doubt but that radio photo letters will be of much greater immediate service in business.
Commerce, like an army, can go forward no faster than its means of communication. The history of industrial advance in all ages shows that with every addition to communication facilities the volume of business has increased. ”

“ When radio service to the eye shall have a comparable development with radio service to the ear, a new era will indeed have been ushered in, when distance will no longer prevent our seeing our friend as easily as we hear him. ”

“ If one puts a nickel under a piece of paper and draws straight lines across it with a dull pencil, a picture of the Indian appears. And that is exactly the way photographs by radio are received, except that a photographic plate is used instead of a piece of white paper, and a pencil of light instead of the pencil of lead, the light pencil changing the exposure in various parts of the successive adjacent parallel lines by reason of the variation of the incoming radio signals. ”

“ It is quite obvious that vision by radio and radio movies can never be attained by a cylinder method, for as the picture must appear to the eye complete, by reason of persistence of vision, it naturally follows that the eye must make up the whole picture from a single focal plane. ”

“ With a radio photographic technique, the result of ten years of concentration on this subject, it may be asserted with confidence that the requirement of a particular application rather than a particular machine is the governing factor in each case; for with full working knowledge of the art, and the special application requirements known, the design of the machine best adapted to that service is a simple matter. ”

“ Each lens draws a line while the relatively slow rotation of the prismatic plates distributes the lines over the whole picture surface, just exactly as the plates do in the Radio Photo Camera.
The Radio Vision receiving set and the Radio Movies set are identical, and one may, therefore, see in one’s home what is happening in a distant place, an inaugural parade, football, baseball, or polo game (and we call it Radio Vision) ; or one may see the motion picture taken from the screen of a distant theatre (and we call it Radio Movies) . ”

“ Dense areas in the negative are built up where the light is successively very bright at the same place in adjacent lines; halftones where the light is less intense; while where the light is very faint, little or no exposure occurs, and shadows will result.
It is thus the lights and shadows which make the picture are built up, line by line, for when this negative is developed, and paper prints made therefrom, the dense areas produce high-lights in the picture; the less dense areas the halftones; and the thin areas the shadows of the picture, person or scene broadcast at the sending station. ”

“ To get music by radio, a microphone converts sound into electrical modulation, which, carried by radio to distant places, is then changed back into sound and we hear the music.
To get pictures by radio, a sensitive cell converts light into electrical current, and at radio distances changes these currents back into light values, and one may see the distant scene; for light is the thing of which pictures are made, as music is made of sound. ”

“ And the delightful thing about it all is that the inaccessible places are benefited the most by radio, those in the out-of-the way places are less lonesome, and the long day of the sick and shut-in is more endurable. ”

“ Graham Bell perfected his telephone here, Professor Tainter the wax cylinder phonograph, and Mr. Berliner the talking machine.
Both the typecasting machines, the linotype and monotype, were invented in the District; and here a stenographer in the Life Saving Service invented the first motion picture machine, the prototype of the projector used in every picture theatre the world over to this very day.
From the hills of Virginia, across the river, the first wireless message ever transmitted was sent into Washington; and from Washington to Philadelphia the first photographs by radio were sent. ”

“ Of course, the sending machine and the receiving machines must run in exact synchronism. This synchronous control of the sending and receiving motors is maintained by the vibration of a rather heavy fork at each station, and adjusted to beat together, with such slight automatic correction by radio as may be required to keep all receiving forks in step with the fork of the station which at the moment is sending. It is a very simple and dependable 30mechanism, by which any number of motors, of any size, separated by any distance, can be made to run in synchronism. ”

“ If the current is strong the sparks pass the gap at a high frequency, while if the current is weak the frequency is less. The range may be from 500 to 5,000 per second perhaps, depending on the current strength, and, of course, the film exposure correspondingly varies, and the different degrees of density of the picture results.
This scheme requires about as small current as is likely to be practical, perhaps, especially when the spark is in a suitable degree of vacuum, and, of course, the incoming radio signals require correspondingly small amplification. ”

“ 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. ”

“ And new means for modulating electric current by changing light values may be expected when the American boy starts to play with this new toy.
There has been a veritable army of engineers engaged in the development of radio as a service to the ear, while relatively few engineers have been developing radio as a service to the eye.
It is believed that the distant electric modulation of light for many purposes will soon become a common phenomena and eventually of inestimable service in science, in engineering, in industry, and in the home. ”

“ Already radio vision is a laboratory demonstration, and while it is not yet finished and ready for general public introduction, it soon will be, for it should be borne in mind that animated pictures differ from still pictures only in the speed of presentation, and the sending of “still” pictures by radio is now an accomplished fact, radio photographs of no mean quality, examples of which appear as illustrations in this volume. ”

“ Why, boys in the whole range of their ’teens discourse with fluency and understanding such mysteries as inductance, impedence and capacities; reactance, reluctance and rotors; harmonics, aerials, and mush; choppers, chokes and cheese; heterodyne, neutrodyne, and iodine; and we oldsters don’t know whether they are talking of medicine, music or food.
The only thing that saves us from everlasting embarrassment is that we have the gumption to keep our mouths shut. ”

“ 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 electric impulses are similar to letter-code dots-and-dashes, for the picture actually opens and closes the circuit, like a telegraph key, the dark portions of the picture sending dashes and the light portions of the picture sending dots. With the point set at one end of the cylinder, and the contact arm advancing longitudinally by reason of the thread on the shaft, the point traverses a spiral around the cylinder until the whole picture is covered. ”

“ Upon the disc is mounted a tiny mirror, and as the suspension of the disc is in the magnetic field held there by the strength of the field itself, it is extremely easily disturbed, so that a small beam of light reflected from the mirror can be vibrated with a very little current through great amplitude. ”

“ Audio radio engineers have been working in the very limited audio-frequency band below, say, ten thousand cycles, whereas the workable range where light instead of sound is employed goes away up to millions of cycles. It is confidently predicted that the next great development in radio is in this area. ”

“ 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.
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105 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 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 ”

“ The electron stream from the outside cylinder to the capsule naturally takes the long path, and as the longest path is down into the capsule, the result is that the small central opening of the capsule glows with great intensity while the other parts of the lamp remain dark. This lamp, Professor Moore advises, has a light and dark frequency of a million per second. ”

“ At first a metallic circuit was employed to carry the impulses representing picture values, but when radio was available several workers immediately began the adaptation of their apparatus to radio circuits. ”

“ 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. ”

“ 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. ”

“ This copy on the metal sheet can then be bent around the cylinder of your sending machine, and sent out by wire or radio, to be received at all stations tuned in. If etched the etching may be filled in with hard wax and this put on the cylinder, and run under the contact finger.
It is possible to write on paper with copper sulphate (blue vitral) solution, for the acidulated line carries the current through the paper to the metal cylinder beneath, and completes the circuit. The acid may even be strong enough to eat through the paper exposing the metal cylinder underneath. ”

“ As for science, why Washington is the scientific 137center of the world. More revolutionary discoveries which have been the foundations of great industries have been made in the District of Columbia than any other ten miles square in all the world. ”

“ This reason alone would warrant one in predicting that the defense of our country is definitely going to pass from the limited activities of the Army and Navy to an Air Department, for the plane has no boundary or limit of range in offense or defense. ”

“ 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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109 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. ”