Vision . by | Baia Radio Photogray phs. Jenkins / / fists. @ he Looe aE ve. RADIO PICTURES Vision by Radio Radio Photographs Radio Photograms eee C. FRANCIS JENKINS W ASHINGTON CopyrIGHTED, 1925, BY — JeNKrinS LABORATORIES, IN WasuinctTon, D. C. * ny : j hae 8 - ‘i vy, v > 2 A? i e a ¥ t : ~ : NATIONAL CAPITAL PRESS, INC., WASHINGTON, D.C. ; at ms {To the splendid young folks, Sybil L. Almand, Florence M. Anthony, John N. Ogle, James W. Robinson, Stuart W. Jenks, and Thornton P. Dewhirst, who so efficiently assisted in the attainment of Photographs by Radio, Radio Vision, and Radio Pho- tograms, this book, in grateful ap- preciation, is dedicated. Mr. C. Francis Jenkins Born in the country, north of Dayton, Ohio, in 1868, of Quaker parents. Spent boyhood on farm near Richmond, Indiana. Attended country school; a nearby high school; and Earlham College. “Ex- plored”’ wheatfields and timber regions of Northwest, and cattle ranges and mining camps of Southwest United States. Came to Washineton, pian 1890, and served as secretary to Sumner I. Kimball, U.S. Life Saving Service. Resigned in 1895 to take up inventing as a profession. Built the prototype of the motion picture projector now in every picture theatre the world over; developed the spiral-wound paraffined all-paper container; and produced the first photographs by radio, and mechanism for viewing distant scenes by radio. Has over three hundred patents; and maintains a private laboratory in Washington. He is a member of the Franklin Insti- tute, the American Association for the Advancement of Science, and founder of the Society of Motion Picture Engineers. Has several times been honored by scientific and other bodies for original research and attainment. Foreword The rapid development of apparatus for the trans- ‘mission of photographs by wire and by radio may now be confidently expected, because the public is ready forit. At this very moment it is going through the same empirical process by which motion pictures arrived, and out of which finally the long film strip was born. In the motion picture development there appeared the spiral picture disc; the picture “thumb book’’; picture cards radially mounted on drums and bands; and the picture film continuously moved and inter- mittently illuminated. But finally the development resolved itself into a single, long, transparent picture film, intermittently moved in the exposure aperture of the projecting machine; and upon this has been built one of the large industries of the world. Doubtless this will be the history of the develop- ment of electrically transmitted photographs, and of radio vision, for many schemes have already been tried and more may yet be seen before the final, practical form shall have been evolved, and this new aid to business and to entertainment shall have taken its place in human affairs. The transmission of a photograph electrically, a portrait, for example, is not so much a matter of mechanism, once the tools are perfected and their operation understood; it is more a matter of blending of line and tone, just exactly as it is with the artist. The great portrait photographer uses the same tools the amateur uses, but an acquired technique of high order enables him to produce a superior portrait, 5 free of chalky contrasts, and soft in tone and blend- ing. Just so in radio photography, it is a matter of simple mechanism, and an acquired skill in its use. The author expects to see, very soon, the radio amateurs using flash-light lamps and electric pens where they now use headphones; and halftones or potassium cells where they now use microphones, for the radio problem between the two is practically the same—if anything rather more simple with light than with sound. And new means for modulat- ing 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. Nor will this service be confined to radio. Present metallic channels now employed for other purposes, 1. e., high tension power lines, railroad rails, city lighting wires, and water pipes, can be made a new source of revenue, and at a ridiculously insignificant cost. Radio is none the less valuable by reason of its application as such a rider on the present metallic grids of every city, and of interurban connections. There are many channels where only space radio can be employed, but the neglect of the application of high frequency currents to metallic channels which lead into every place of business, and into every home, is unnecessary waste. | The author confidently believes the application of 6 these several ideas to the control of light at distant points is the next great advance in electricity, and to hasten such development the information in the following pages is set down to assist the research worker and the application engineer. The mechan- isms and circuits herein disclosed may be accepted with assurance. 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. THE AUTHOR. Contents Page Amstutz Machines....... 73 Avid. ST, Co, Picturesss7 85 Baker’s Scheme.......... (i Belin Machine........... 83 Braun Tube Receiver... .. 91 GapillarysPen* ten 20 arene 40 Gircwite’tadiow: ener r 117 Code Pictirést. 232. es 89 Colomby Radigv gaara . 93 Control One ee ee 29 Corona Lamp? see ee 51 Dot Pictures +, -o ee 88 Duplex Machine......... 105 Electrograph of 1900..... TES Electrolytic Receivers..... 46 Engraving Receiver...... 73 Eve Radio Service....... 39 FilamentsUanip ee 28, 50 First Radio Channel...... 67 First Picture Machine... .120 Fournier and Rignoux.... 81 Galvanometét = 32 ceLe 48 Genesis of Radio......... 127 Glow Campa .0 ere 29 Halftone, filled in........ 41 High Speed Camera...... 25 Historical Sketch, Jenkins.118 Hook-ups—Jenkins....... 117 Initial Activities aa. a. 25 Ink Pen Receivers ....... 46 Korn, Dr., Machine...... 79 Lens Drum Machine...... 116 Lens Disc Machine. .114, 115 Light Cell ee 42 Page Light Sources 7) saa 112 Light Wedge...cc5 eee 48 Mechanisms employed.... 40 Medals... eae 121-126 Motion Picture Projector. .120 Multiple Signals......... 30 Nipkow & Suttonsa aes 71 Oscillograph Receiver..... 47 Patents, list Grasse 132 Perforated Strips. yee Photographic Receiver.... 47 Pneumatic Valve......... 49 Prismatic Ring... .25, 98, 110 Prismatic Ring Machines. 95 Radio Circutte3a55eaaee 117 Radio Corp. Pictures..... 87 Radio Motor] ae 30 Radio Visions... ee 33 Radio Vision Machines. . . 109 Receiving Machines...... 45 Receiving Methods. = 26 sending Machines........ 40 Sources of [ight? 2a 112 Spark Gap Source........ 50 Strip Machines. .a 103 Stroboscopic Lamp....... 30 Sutton & Nipkow........ 71 swelled Gelatin: 72a 41 Synchronizing Forks..... 101 Talking Machine....... relies Transmitting Methods.... 25 Washington ?: 3... 133 Zinc Etching 3). 40 Illustrations Page Peto 1, Co-example... 84 Amstutz Machine........ 72 Baker Machine.......... 76 Belin Machine:.......... 82 eee ICUUTE. . 2... oe ees 89 PGP IaentSe ss. kc... 52-66 PROTO cre... es 100 MDGteEiCLUTe. 4 tan. ok 88 Pio eNiachinie......... 104 Cw wietgn 6) ta 74 Examples Photograms. .35-38 Examples Radio Photos.17—23 Experimenter’s Machine. . 106 Peer iouire Projector... .120 High Speed Camera...... 124 Pomme aampie,.......... 78 Pee OVIICeS.....5....5.. Lt Coons Wireless......... 68 Page INiedaIs een es ae 121-126 POLOOTARIS Iter, 1a. ths 3208 Prismatic Band Ring..... 99 Prismatic Dise King 29... . 97 Prism Combinations. .110, 111 Radio Color Example..... 92 Radio Corp’n Picture..... 86 Radiowiodkoup sss. 117 Radio Photographs... ..17—23 Radio Photo Camera..... 96 Radio Photo Transmitter... 94 Radio Picture Scheme. ...113 Radio Vision Machines. . .108 R. V. Mechanisms... .114-116 pecing Dvenatiow a S42: 80 peeing by Wire... .....4-. 70 LOL a VV OL Ceee eer An 1, 122 olan] JNU Rekal@nbr holt, Gangs einen 102 7 . ¥ =i = ey e ad Vision by Radio C. FRANCIS JENKINS HE earliest attempts to send pictures and to see electrically date back some fifty years, being practically coincident with efforts to transmit sound electrically. 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. Some remarkably fine examples of pictures trans- mitted by both wire and radio have been produced in recent months; most of them showing the lines, but some of them without lines at all, z. e., true photographic results. | And as the transmission of images from living subjects in action differs from “‘still’’ pictures only in that they are more rapidly formed, it naturally followed that the solution of this problem should also be undertaken. When radio service to the eye shall have a com- parable 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. Our President may then look on the face of the King of England as he talks with him; or upon the countenance of the President of France when ex- changing assurances of mutual esteem. 11 The general staff of our Navy and Army may see at headquarters all that a lens looks upon as it is carried aloft in a scouting airplane over battle front or fleet maneuvers. And from our easy chairs by the fireside, we stay- at-homes can watch the earth below as a great ship, like the Shenandoah, carries our flag and a broad- casting lens, over the mountains and plains, the cities and farms, the lakes and forests, of our wonder- ful country. In due course, then, folks in California and in Maine, and all the way between, will be able to see the inaugural ceremonies of their President, in Washington; the Army and Navy football games at Franklin Field, Philadelphia; and the struggle for supremacy in Our national sport, baseball. The new machine will come to the fireside as a fascinating teacher and entertainer, without language, literacy, or age limitation; a visitor to the old home- stead with photoplays, the opera, and a direct vision of world activities, without the hindrance of muddy roads or snow blockades, making farm life still more attractive to the clever country-bred boys and girls. Already audible radio 1s rapidly changing our social order; those who may now listen to a great man or woman are numbered in the millions. Our President recently talked to practically the whole citizenship of the United States at the same time. When to this audible radio we add visible radio, we may both hear and see great events; inaugural ceremonies, a football, polo, or baseball game; a regatta, mardi gras, flower festival, or baby parade; and an entire opera in both action and music. Educationally, the extension worker in our great universities may then illustrate his lecture, for the distant student can see as well as hear him by radio. 12 It is not a visionary, or even a very difficult thing to do; speech and music are carried by radio, and sight can just as easily be so carried. 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. To further show the close relation, it might be added that im receiving sets these same electrical values can be put back either into sound with head- phones or into light with a radio camera; although it may be admitted that such radio signals do not make much sense when with headphones one listens to the pictures. 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. | Just as is done in radio photographs the picture surface is traversed by a small spot of light moving over the picture surface in successive parallel adjacent lines, with the value of the lines changed by the incoming radio signals to conform to a given order, the order being controlled by the light values of the scene at the distant sending station. 13 In sending pictures electrically, there have been but two methods employed, perhaps the only methods possible; namely (a) a cylinder mechanism; and (0) a flat surface. Without exception, every scheme which had attained any degree of success, before the author adopted flat surfaces, has depended upon synchronous. rotation of two cylinders, one at the sending station with the picture thereon to be sent; and the other at the receiving station where the picture is to be put... ~ ; Perhaps the very obviousness of the cylinder scheme, and that there are no patents to prevent, explains why, it has been employed by so many. And there have been many workers in this line of endeavor; for example, in England, Lord Northcliff, sir Thompson, Mr. Evans and Mr. Baker; in France, MM. Armengaud, Ruhmer, Rignoux, Fournier, and Belin; in Germany, Paul Nipkow, Dr. Anchutz, and Dr. Korn. , | In America, Mr. Ballard, Mr. Brown, and Mr. Amstutz, the latter deserving particular mention, for, from a distant picture, a swelled gelatine print, he engraved a printing plate which could be put directly on a printing press for reproduction. All these many workers have adopted the cylinder method of sending and receiving, and all have arrived at approximately the final stage of development permitted by concurrent science. It may be well to explain that, in these older schemes, the picture to be sent is wrapped around the cylinder, usually a cylinder of glass where light sensitive cells are employed, mounted on a rotating shaft, which also has longitudinal displacement. The light values which make up the picture are converted into electric current of corresponding 14 values and put upon a wire or other channel which delivers them to the distant receiving station. At the receiving station a suitable film-like sheet (paper, for example) is wrapped around a cylinder similar to that at the sending station. As. this cylinder is rotated and longitudinally advanced under a stationary point in contact with the paper on the cylinder, a spiral is traced thereon. As the incoming electrical current represents picture values, and as the two cylinders are turning in exact syn- chronism, a picture duplicate of that at the sending station appears thereon. After the picture is com- pleted the paper sheet can then be taken off the cylinder and flattened out for such use as may be desired. 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. The attainment of “‘television”’ or Radio Vision, as it is now coming more commonly to be called, requires that the sending shall be from a flat plane, and reception on a flat plane, and a modulation which will give not only the high lights and shadows but the halftones as well. These ‘“‘flat planes’’ may, of course, be the focal planes of the lenses employed at the receiving station, and from the focal depth of the lens at the sending station where the picture may perhaps be taken from living actors in the studio or from an outdoor scene. At the receiving station the ‘“‘flat surface’? may be a photographic plate, a white wall, or a miniature of the usual “‘silver sheet’”’ of the motion picture theatre. It may aid in a clearer and quicker understanding 15 of the text if the words telephone and television be limited to metallic circuit service, while radio phone and radio vision is applied to radio carried signals, and this designation will be employed in the following pages. is a ql i wal f ml ; | L This and succeeding pages are examples of photographs re- ceived by radio from a distance, by the Jenkins system, some of them from Washington to Philadelphia, and represent the best work done in 1922, 1923, and 1924. Pte LIVITIES: The author’s work began with the publication in the Motion Picture News, of October 4, 1913, of an article entitled ‘‘Motion Pictures by Wireless.’’ This contemplated the employment of a flat receiving surface, but in the light of subsequent experience the scheme proposed therein is believed to be im- practical. It did, however, provoke discussion of the subject and initiated the work which was there- after rather continuously prosecuted, except for interruption to aid in the great World War. After failure to find a practical, workable mecha- nism made up of devices already in use in applied science, diligent effort was made to discover the necessary, missing part. PRISMATIC RING: At length a device described as a prismatic ring was developed, a new contribution to optical science. In use it is comparable to a solid glass prism which changes the angle between its sides, giving to a beam of light passing therethrough a hinged or oscillating action on one side of the prism while maintaining a fixed axis of the beam on the other side of the prism. As a convenience in fabrication this prismatic ring is ground into the face of a glass disc of suitable size, of selected mirror plate, which gives the ring its own support on the rotating shaft upon which it is mounted. TRANSMITTING METHODS: Success in sending pictures by radio from flat photographs and receiving them on flat photo nega- 2 tive plates (and subsequently of radio vision), really began with the perfection of automatic machines for the making of these prismatic rings, for by means of these prisms and a light sensitive cell at the sending’ station the light values which make up the picture are converted into electrical values, and broadcast. So to put this picture on a radio carrier wave we simply slice up the picture (figuratively) into slices one-hundredth of an inch in width, in the best pic- tures, by sweeping the picture across the light sensitive cell by means of these rotating prismatic rings. With each downward sweep the picture is moved one-hundredth of an inch to the right until the whole picture has crossed the cell, the cell con- verting the light strengths of the different parts of each such slice into corresponding electrical values. The process very much resembles a bacon slicer in the market, each slice showing fat and lean. Similarly these imaginary slices of our picture show light and dark parts, and these lights and shadows moving across the sensitive cell produce correspond- ing strength of electric current, modulating the radio carrier wave of the broadcasting set accordingly. Further, of course, it is immaterial whether the current modulation is taken directly from a flat photograph, from a solid object, or from an out-door scene at which the transmitter is pointed. RECEIVING METHODS: To put these light values back together again at the distant receiving station to make up a negative of the picture being broadcast from the sending station, it is only necessary to reverse the process; first, with a point of light to draw lines across a photographic plate, which the rotating prismatic 26 rings do; and, second, to vary the density of the different parts of the successive lines corresponding to lights and shadows of the picture at the sending station, and this the varying strength of the incoming radio signal does by varying the intensity of the light. 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 there- from, 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. It is simply that a photographic negative has been made of what the lens at the sending station is looking at. So, then, to receive pictures by radio, it is only necessary (1) to cover a photographic plate in parallel adjacent lines, and (2) to vary the density of the lines, to build up the shadows, the halftones, and the high-lights of the picture. | 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 1s 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. The scheme is just a long camera with miles instead PH of inches between lens and plate. For example, the lens in Washington and its photographic plate in Boston; with this exception, that the one lens in Washington can put a negative on one, ten or one hundred photographic plates in as many different cities at the same time, and at distances limited only by the power of the broadcasting station, radio instead of light carrying the image from lens to plate. The time for transmitting a picture depends upon the size of the picture and strength of light, say, from three to six minutes, using a filament lamp as a source. The radio photograph receiving instruments are rather simple and inexpensive and, like a loudspeaker, can be attached to any standard amplifying audio- radio receiving set. FILAMENT LAMP: For the light source for radio photographs a fila- ment lamp is employed, and in a single turn coil enclosed in a hydrogen atmosphere. This miniature filament coil is imaged on a photo negative plate, and the variation in the light is caused by putting the incoming radio signals through this lamp, per- haps after the filament has been brought to a red glow by a battery current. By adjusting the speed of the motor to the temperature change of this filament soft gradations of light and shade are obtained which probably can never be equaled by any other device, a photograph of true photographic value, entirely free of lines. : The author wishes to take this occasion to express his appreciation of the splendid assistance of the General Electric Company, under the personal supervision and hearty cooperation of Mr. L. C. Porter, who from the very first has shown his con- 28 fidence in the ultimate successful conclusion of this development. GLOW LAMP: For the high speed radio photograms, where only blacks and whites are needed, a corona glow lamp of very high frequency has been developed. This lamp is lighted by the plate current of the last tube of the amplifier; and as the lamp can be lighted and ex- tinguished a million times a second, it is obvious that the permissible speed is almost limitless, and a thousand words per minute is believed ultimately possible. This lamp has been developed for the author by Professor D. McFarlan Moore, an expert in lamps incorporating this phenomena, and who some years ago, it may be remembered, produced a lamp of this type more than two hundred feet long. It is prob- ably safe to predict that no other lamp will ever be able to compete in speed. As photography is the quickest means of_copying anything; and radio the swiftest in travel, it seemed logical that the two hitched together should con- stitute the most rapid means of communication possible. CONTROL FORK: 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 depend- 29 able mechanism, by which any number of motors, of any size, separated by any distance, can be made to run in synchronism. RADIO MOTOR: Another scheme of the rotary type, perhaps even better adapted to the distant control of large motors, is a small synchronous radio motor driven by power carried by radio from the broadcasting station to the receiving stations. It is, of course, rotated partly by radio power from the distant station, and partly by local current, just as a loudspeaker is operated. These small motors, rotating in synchronism with the motor at the sending station, control the rotation of a larger motor in each receiving camera, and so all stations keep in step. STROBOSCOPIC LAMP: Of course, it would be fatal if it were necessary to wait until the picture was developed before it could be discovered that the receiving camera was getting out of control. So a special ‘‘neon’’ lamp is located to shine on a revolving marker on the motor shaft of the receiving instrument, and flashed by the incom- ing radio signals, which latter bear a definite relation to the rotation of the sending station motor. SAME WAVE: It should be noted that the same radio wave carries both the picture frequency which builds up the photograph and the synchronism frequency which controls the’ motors, and also that it lights the stroboscopic lamp. ai MULTIPLE-SIGNAL RADIO: A further advance step was made when an audible message was added to the same radio wave which 30 carried the picture. This is done by modulating the carrier wave to give audibility, while interrupting the same carrier wave at a frequency far above the audible range, say, two hundred thousand cycles, to make our picture. By means of this duplex employment of the same radio wave, it is possible to get, for example, both the gesture and the voice of an inaugural address; the play and the cheers of a national sport; or the acting and song of grand opera. Perhaps it might be explained that synchronism in visual-audible radio reception is accomplished by the simple expedient of keeping the radio picture “framed,’ exactly as this is done in the motion picture theatre. 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. Obviously a third electrical means of communication will enlarge business, and speed up commerce and industry. As an aid in national defense the chief of staff of the Signal Corps of the Army, in a recently published report to the Secretary of War, said (Washington Star, November 22, 1924): “Looking into the future of signal communication for a moment, it appears that the basic method of breaking messages up into words, words into letters, Jl letters into dots-and-dashes, and then passing these through the wrist of an operator, as has been the practice since Morse’s fundamental invention of the electric telegraph, seems to be nearing the end of a cycle. Mechanical transmitters with higher speed qualities are becoming stabilized and American invention seems to be making further and rapid progress in associating photography with~ radio, which bids fair to revolutionize fundamental methods of transmission. ‘“The message of the future, whether it be written, printed, of mixed with diagrams and photographs, including the signature of the sender, will, it seems certain, soon be transmitted photographically by radio frequency at a rate tens of times faster than was ever possible by the dot-and-dash methods of hand transmission. ‘Military messages of the future, particularly in active operations, may contain diagrams and sketches, or even entire sheets of maps, all trans- mitted as part of the same message and by means of which detection or listening-in will be reduced to a very low minimum.” The author suggests that it might be added that the newcomer, the radio photogram, has merits distinctly its own, e. g.: (1) It is autographically authentic; (2) it is photo- graphically accurate; (3) it is potentially very rapid; (4) it is little effected-by static; (5) it is not effected by storms; and (6) it is automatic and tireless. It can also be used to enlarge the individual news- paper’s influence and prestige by the establishment of photostat branch printing plants at strategic points, like summer camps, and winter resorts, and at ridiculously little cost. Such copies of the news, financial and market report pages of the paper could be distributed in these distant places before they could possibly appear on the streets of the home city of the paper. 32 Of course, produce market reports, stock market news, and similar matter could be so distributed very much quicker than could be done by any other system, certainly so to the farmer and gardener. RADIO VISION: Radio Photographs and Radio Vision, when both are done by the flat-plate method, are identical in principle, the difference being only in the speed of the apparatus, with such modification in the appara- tus as will permit of the required speed. Just as in the Radio Photograph the picture surface of the Radio Vision is covered with a small spot of light moving over the picture surface in successive parallel lines, with the light value of the lines changed by the incoming radio signals to conform to a given order, the order being controlled by the distant scene at the sending station. And as the whole picture surface is covered in one-twelfth to one-sixteenth of a second, persistence of vision of the human eye is sufficient to get the picture from the white receiving screen—a photo- graphic plate is not necessary. 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, chang- ing in light value to correspond in position and inten- sity to the light values of the scene before the lens at the broadcasting station.» But when the machine is speeded up until the suc- cession of lines recur with a frequency which deceives the eye into the belief that it sees all these lines all the time, then a picture suddenly flashes out on the white screen in all the glory of its pantomime mystery. 33 To accomplish this, the apparatus must be speeded up until a whole picture can be assembled on the screen, say, in one-sixteenth of a second, to be seen by the eye directly. It was necessary to modify the Radio Photo apparatus to permit this increase-ins speeding lens disc is substituted for the fast pair of prismatic plates. 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). The Radio Vision receiving set, as now designed, is very simple; namely, a mahogany box, or small lidded cabinet, containing, beside the radio receiving set and a loudspeaker, only a small motor rotating a pair of glass discs, and a miniature, high frequency lamp for outlining the pantomime picture on a small motion picture screen in the raised lid of the cabinet, synchronism being maintained by the simple expe- dient of ‘‘framing’’ the picture on the screen exactly as this is done in a moving picture theatre. The author wishes to acknowledge his indebted- ness to his friend, Professor D. McFarlan Moore, for a word name for this new device, i.e., ““telorama”’ for the radio vision instrument, and ‘‘teloramaphone”’ for the instrument when it includes simultaneous reproduction of the music or sound beac 2 the living scene. 34 ie "NOTLLVOINAMROD JO SNV3IAN Sli NYHL YSLSVA ON 09 NVO AYLSNONE ‘AWYY NV 3yE7 “aSNvI39 AYLSNONI dN GISdS ATINAYIONOM GINOK JONTOITIZLN 40 JONVHO “X3.NV HONS “ANVId=TIVN AS SIVNIDIHO JHL JO ANBAITSG GsVd “OFT SHI MVHL YSHLVY 1HDI7 4O O33dS JH LY SyzL197 S$S3NISNa UNO JO SJ1dOD DIHdVYDOLOHd OVOWY AD YIAIVIO VWIK LNIXLYVd3d JOPSIO“ISOd JHL N3HM JNOD NOOS JAIL J3HL VIIM “ATHO Y¥O ZHI OL SS3¥00V NV N339 SWH O10VY 3NOSOLIYIH JYSHM “JAR FHL OJ JOIAYIS O1OVE WV 3O ONINNIDSS JHL S' LY °O4GWVH 4O 033dS FHS ONY ‘Y3LL97 O3HdVYDOINY NV 30 YSLOVYVHD JVANSHINY JHL SVH LI *S3LNNIN JAI4 NE VAVNYd OL NOLONIHSVA “dLHSAVSLS AG JO AVILS “Nf OLGVY AG S3DVSSIX ONILIINSNVAL 4O QOHLIW V “Y9Li37 OL0Kd “O1r0VY- MIN YNO JO DWdWVXS NY S} SHHL — NOSYFONSH" 100 YV30 AN “O°O‘NOLONIHSUR “TVWY3NID YIISVALSOd LNVLSISSY *>Z61°t YZ80LI0 “NOSUSONSH WVWd* 709 DY ee Op Py go , } ae pepe : ged es Ae af Z pa ge by? % fe ea > yee e he oe a a Wi op ovr py 2 xy, : a 2Wi z i- Ss Sy - \2. 7 I + P-@ / PPE Mgt eee ot YECE fF —< ees pas pr esp? ids tp 7) Oe 7; of roa PEs LL pe as v AY roe Za fo a Ze - ENGINBBR-CAPTAIN, I. J. N. usec uf nth ‘ his eae Otfice HARRISBURG October 23, 1923. Mr. C. Francis Jenkins, 5502 Sixteenth Street, Washington, DeC. 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 heertiest thanks for all the trouble you took in getting it <4 Sincarely your & x ves Vials Ps I339 -ISS5(7DIVERSEY 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 congratula- tions on making such wonderful pro- gress 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 an, Sincerely, Rothacker Film Mfg.Co 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 VoimeeLetter .of nite 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, 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 Pho- tograph--it is wonderful! What is there left to be discovered? Appreciating your friendly interest, I am, Very truly yours, DEPARTMENT OF COMMERCE OFFICE OF THE SECRETARY WASHINGTON February 1,1924. Mr .C .Francis Jenkins, 1519 Connecticut Avenue, Washington ,D.Cc. Dear Mr.Jenkins: I Wish to express my appreciation for the photograph which you so kindly sent me. It represents avery startling development in radio and sometime aren I have some leisure I would be interested in discussing the method with you. Yours faithfully, CARL AKELEY J7TH STREET AND CENTRAL PARK WEST New YORK CITY March 16,1925. Dear Mr .Jenkins: You are perfectly wel- come to publish anything I may have written you. I think few people realize or appreciate the practical possivilities of the transmission of radio photographs and the high develop ment to which you have brought this art. I congratulate you on your suc- ce@ss and Wish a speedy realization of your dreams. Sincerely yours, Leorl be kes Wr .C .Francis Jenkins Jenkins Laboratories 1519 Connecticut Avenue, Washington DC 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 con- siderable 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 Washing- ton; a duplicate station being set up on top of Catoc- tin 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 communi- cation without the aid of wires.’’ Later (1869) a bill was introduced in the U. S. Congress to incorporate the Loomis Aerial Tele- graph 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— 67 er? Sa S Oy Are % a a 2 : Nyy att N hy. SNA 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 Ualted States Patent Office at Washington. ERG Ra ‘The system consists of causing electrical vibra- tions, 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 fol- lows another from the point of disturbance to the remotest shores; so that from any other mountain top upon the globe another conductor which shall re- ceive the impressed vibrations may be connected to an inductor which will mark the duration of such vibration, and indicate by an agreed system of nota- tion, 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. 69 Nipkow and Sutton One of the most interesting examples of the at- tempts to see by radio was made the subject of a patent by Nipkow in 1884. The proposed trans- mitter 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 Profes- sor 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 Tele- graphic Journal, 1881, Vol. 9, page 83; and later almost exactly duplicated by M. Henri Sutton, and rather fully described in Lumzere Electrique, Vol. 38, page 538, 1890. 71 The Amstutz System Of all the mechanisms which have been designed for the transmission of pictures electrically, that of Meorinistutz, of Valparaiso, Indiana, U. S. A., in the author’s opinion, stands out as the most con- Spicuous, 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 photo- graph. The amount of relief was in direct propor- tion 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.) 73 FROM TAKEN URE WAS IVING E Cr ECE S Pr HE R HAVING B HUNDR G THI AFTER fACHINE N 4b IGHY TELE- \- ~ TRANSMITTED F OVER N “s E aw ~ = TILES = N APH WIR c1> 4 R ATIONAT. K H I “| Bs INTERN LECTRO-GR 900. APH Co. . 4 }j4 ELAND. ©. CIE 1 lst, OV. te 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. 8S. 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-pietures. 75 1910.--Baker. 1. PHOTOGRAPH WIRED The Baker Machine The machine of the opposite illustration, “the telestrograph,’”’ is the invention of T. Thorn Baker, Esq., of England, and “‘was used by the London Datly 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 tes! | The receiving cylinder carried ‘an absorbent paper impregnated with a colorless solution which turns black or brown when decomposed by the in- coming 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.) 77 2. FASHION PLATE TRANSMITTED BY PROFES 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 obstruct- ing “‘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.) 79 Rignoux and Fournier Scheme One of the early suggestions had for its funda- mental 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 cor- responding 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 re- ceiving end, each but one-fiftieth of an inch in diam- eter. Such a problem would seem to present difficul- ties, 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.) 81 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 gal- vanometer 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.) 83 reece ssc 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 repro- duced 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. 85 hea 4, A ey Aeiey, Dry ao ; Radio Corporation Machine The accompanying “‘photoradiogram”’ is a develop- ment 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.) : 87 1 -e weetee +. nan + ee re reece ences 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 pic- ture to be sent is divided into many small squares with varying values of dark in the squares. Seven- teen 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 correspond- ing 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 half- tones; and still other collections of very minute dots make up the light areas. (From the New York World.) 88 LVGIS _ MBGwO MITIO MTITO QIjBQ QuyoQ S$DIXQ SOIsO TEIBQ TGGQO TMFQQ TSEUA TDERA SMEBUO QKEMQ OTEQQ MVEQQ MIEKA MEEIQ MDETQ MBF WQ LVGIOQ LMGKO LIGMQ KVFWQ KIFTOQ LDF BO LAEWQ LIBGO LQDQQ LUBWOQ MQAVOQ SAAMQ SKAMQ TDAVQ TLBIQ TUABTQ TXBVO TVDAA — TXppA VADMQ UAEIQ TWELA UBETOQ IXFFO TUFQQ TVFVQ TUGAQ TWGMQ UAGXO TSIGO TGIFO MQFEE QFFEQ QMFIO QSFMG ‘QSFAQ QBEWA QAEVA MMEVQ QAFDM QIFDM ’ MTFFE GBREO OMFLG QGFLQ MREIO MTFFD QAR IQ QEFKQ QGFIO OIPGK QBFIQ QFFIO- QFFIQ QEFFM QHEGY QYFIS . QEEKA QFFLE Fig. 3. This is Part of the Program or Code Telegraphic Message—the Form in Which the Picture is Flashed Over the os Tes. 5 z Fig. 4. This is the Complete Outline Ob- ‘S : Ce tained from the Code, with Proper Shade : Wied oo Lf ye Letters Within Enclosures (Right). | Tinto Wive Decrees cf Shade 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.) 89 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 So oteimeepiciire 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. 91 Pictures by Radio in Natural Colors It is well known that pictures in color are in com- mon use in magazine printing, in window transparen- cies, decorations, etc. The process consisting in mak- ing 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 nega- tives, 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 trans- mission of the three successive pictures which after their reception are to be colored and combined into one. 93 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, modu- lated 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.