From the beginning of history pictured information has been the most quickly comprehended, and longest mentally retained.
A hundred years ago photography was invented, eliminating the possibility of dexterous error in pictures.
Thirty years ago motion was added to the picture, and we get a sense of direction, comparative size, and approximate location.
Now radio as a carrier is wedded to the action picture so that instantaneous delivery is attained for the most inclusive of all means of information.
Naturally, all of these have been employed in the national defense, and just as naturally it follows that this latest, radio vision, should, in anticipation, be so considered, for it will enable the chief of staff to sit in his office at headquarters, and watch the distant battlefield, on sea or on land. He can constantly note the troop movements or the fleet maneuvers, both his own and the enemy's.
The broadcasting instrument aboard the scouting airplane, by which this is attained, is, then, literally, the eyes of the chief of staff, the radio being the nerve tendrils which carry the visual impressions from the scouting plane back to the brain of the commanding officer.
While it is true that such radio vision has not actually been done from a plane in flight, it could be done at any time, for it is a daily laboratory demonstration.
On June 13, last, this new thing, radio vision, was demonstrated when Secretary Curtis D. Wilbur, and others of the Navy; Acting Secretary, Judge S. B. Davis, Department of Commerce, and friends, and Director, Dr. George M. Burgess, Bureau of Standards, saw, in a Washington laboratory, what was actually happening at the time in the Anacostia Air Station several miles away.
It is obvious, therefore, that refinement is all that remains to be done before the chief of staff of any branch of our governmental service may see on a screen in headquarters everything that the broadcast lens looks upon as it is carried aloft by a scouting airplane.
Of course, like every new thing, it is mysterious until the simple principles and mechanisms employed are understood, but no longer.
To us in the laboratories it does not seem mysterious or impossible, or its attainment deserving of any particular comment.
We are familiar with each wire and screw and lens and tube, and our surprise would come if the combination failed to give us radio vision.
Until just a few days ago I have been so busy I have not had the opportunity quietly to consider radio vision from the layman's point of view. I had seen in the problem only the need of getting together the necessary elements and putting them into a working combination. Some of these I found ready at hand in science and engineering; some others I had to invent—that is, physically create from a mental concept; the ring prism, for example, a new contribution to optical science.
To me it does not seem strange that you may presently plug into the loudspeaker jack of your radio receiving set, a small box-like device which will project a picture on a small white screen; an action picture of some event then taking place down town, or in some distant city; for example, a presidential ceremonial, a national sport, a spectacular event.
It is the development, the refinement of each separate element, that is now occupying my attention, and that of the keen young men and young ladies who are assisting me, and I think I may confidently promise you such an attachment before many moons.
Let's see whether there is warrant for assuming that it is a simple problem; whether there is really any mystery in the thing, after all. Let's analyze our problem—take it to pieces and examine it in detail.
These are the essentials. First, a picture of the remote scene; second, have the picture repeated fast enough to reproduce the action on the scene; and third, we want it carried into our homes from the distant location, the baseball park, let's say. That's the problem, and that is all there is of it: namely, a radio-carried, continuous-picture of a distant activity.
If one put one's head under the black cloth of an old-fashioned camera, pointed at the baseball game, one would see in miniature on the ground glass an exact reproduction of the game as it goes on. In this case, it is carried by light from the ball diamond to the ground glass screen. That ground glass action picture is exactly what we want, only we want it in our homes; but daylight alone won't do, for light goes only in straight lines, and obstructions cut it off. We must, therefore, have some kind of carrier which can go around obstructions, and through the walls of our houses. A copper wire will do, but a wire carries only to one place. Radio, however, carries everywhere, so we adopt radio instead; besides which, radio is a convenient and cheap carrier.
Next we come to the consideration of the picture. Now a picture is nothing but some black and white mixed up together in a definite order. Pick up a newspaper, a book, or a photograph, and examine it analytically; it is made up of lights and shadows only.
But how are we going to make radio, which has carried these lights and shadows from the ball park to our home, reproduce the ball game as a picture.
Don't you remember that when we were little tikes, mother entertained us by putting a penny under a piece of paper, and by drawing straight lines across the paper she made a picture of the Indian appear. Well, that's the very way to do it.
In our homes we take a small square of white blotting paper, fasten it on the wall, and move across it in successive lines an image of a small light source. If this little light spot moves across the screen swiftly the eye sees it as a line, like the circle of fire of our youth when we swung a lighted stick.
Now, when these successive lines, one under another, succeed each other so rapidly that the whole screen surface is covered in one sixteenth of a second we have motion picture speed, and the whole surface appears continuously illuminated.
But, when the illumination is controlled by the incoming radio current, put through our lamp, the strong signals will make the spot of light on the screen very bright in certain places; the weaker signals less bright in other parts, and when there are no signals at all the lamp goes out, and black spots appear. Our screen is no longer uniformly lighted, but the light is dabbed about over the screen.
Because a picture is only a collection of these little dabs of light put around in different places on the screen, it will readily be seen that these radio light variations, when they follow a predetermined order, make up our picture of the ball game, just as the humps on the penny made up a picture of the Indian.
On the broadcast apparatus the picture image of the baseball game is "sliced" up into slices, like a bacon-slicer in the market, and the lights and darks sweeping across a light sensitive cell are converted into electric currents which, carried by radio to your home, are converted back into light values, a "motion picture" of the distant ball game.
So that's the way we do radio vision in your home; that is, the incoming radio signals turn the light up and down as it is moved swiftly over the screen, and you "see" the distant scene.
Easy, isn't it? You can go out into the woodshed and build yourself one now. Of course, if you have no woodshed where you can get off by yourself and think clearly, you are out of luck.