Chapter C: Francis Jenkins

WASHINGTON

COPYRIGHTED, 1925, BY
JENKINS LABORATORIES, INC.
WASHINGTON, D. C.

¶_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 Photograms, this book, in grateful
appreciation, 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. “Explored” wheatfields and timber regions of Northwest, and cattle ranges and mining camps of Southwest United States. Came to Washington, D. C., in 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 Institute, 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 transmission of photographs by wire and by radio may now be confidently expected, because the public is ready for it. 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 intermittently 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 development 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, free of chalky contrasts, and soft in tone and blending. 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 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.

Nor will this service be confined to radio. Present metallic channels now employed for other purposes, _i. 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 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 mechanisms 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.

Contents

Page
Amstutz Machines 73
A. T. & T. Co. Pictures 85
Baker’s Scheme 77
Belin Machine 83
Braun Tube Receiver 91
Capillary Pen 46
Circuits, radio 117
Code Pictures 89
Color by Radio 93
Control Fork 29
Corona Lamp 51
Dot Pictures 88
Duplex Machine 105
Electrograph of 1900 75
Electrolytic Receivers 46
Engraving Receiver 73
Eye Radio Service 39
Filament Lamp 28, 50
First Radio Channel 67
First Picture Machine 120
Fournier and Rignoux 81
Galvanometer 48
Genesis of Radio 127
Glow Lamp 29
Halftone, filled in 41
High Speed Camera 125
Historical Sketch, Jenkins 118
Hook-ups—Jenkins 117
Initial Activities 25
Ink Pen Receivers 46
Korn, Dr., Machine 79
Lens Drum Machine 116
Lens Disc Machine 114, 115
Light Cell 42
Light Sources 112
Light Wedge 48
Mechanisms employed 40
Medals 121–126
Motion Picture Projector 120
Multiple Signals 30
Nipkow & Sutton 71
Oscillograph Receiver 47
Patents, list of 132
Perforated Strips 43
Photographic Receiver 47
Pneumatic Valve 49
Prismatic Ring 25, 98, 110
Prismatic Ring Machines 95
Radio Circuits 117
Radio Corp. Pictures 87
Radio Motor 30
Radio Vision 33
Radio Vision Machines 109
Receiving Machines 45
Receiving Methods 26
Sending Machines 40
Sources of Light 112
Spark-Gap Source 50
Strip Machine 103
Stroboscopic Lamp 30
Sutton & Nipkow 71
Swelled Gelatin 41
Synchronizing Forks 101
Talking Machine 107
Transmitting Methods 25
Washington 133
Zinc Etching 40

Illustrations

Page
A. T. & T. Co. example 84
Amstutz Machine 72
Baker Machine 76
Belin Machine 82
Code Picture 89
Comments 52–66
Control Fork 100
Dot Picture 88
Duplex Machine 104
Electrograph 74
Examples Photograms 35–38
Examples Radio Photos 17–23
Experimenter’s Machine 106
First Picture Projector 120
High Speed Camera 124
Korn Example 78
Light Sources 112
Loomis Wireless 68
Medals 121–126
Photograms 35–38
Prismatic Band Ring 99
Prismatic Disc Ring 97
Prism Combinations 110, 111
Radio Color Example 92
Radio Corp’n Picture 86
Radio Hook-up 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
Seeing by Radio 80
Seeing by Wire 70
Story World 122
Strip Machine 102

Vision by Radio