THE WONDER OF TELEVISION
Electric Eyes that Scan the World

by J.L. BAIRD

We have heard how man has harnessed the sound waves and brought them across the world, at the speed of light, to his own fireside. Is it possible to harness the light waves themselves, and see to the ends of the earth? To-day, it is certain that man can do this. To-morrow, we shall "look-in" to the Test Match in Australia or the towering skyscraper in New York just as to-day we can listen-in to the story of the game from Sydney or the orchestra playing on Broadway. More complicated than wireless, with its wave-lengths, valves and hosts of things with long and curious names, this new science of Television, or "seeing at a distance," is one of the most wonderful achievements of man. The delicate instruments which make it possible we owe largely to the genius of a British scientist, Mr. John L. Baird, who, after years of experiment, succeeded in 1925 in "looking-in" for the first time to a distant picture. In 1928 he was able to flash a scene across the Atlantic to-day the "television nights" are a regular part of the broadcasting programme. Here we have an account, written for us by Mr. Baird himself, of how this wonderful invention works and what it can do.

TELEVISION can best be described by comparing it with wireless telephony, or better still, with broadcasting. For when man invented the wireless telephone, he made for himself a third ear—an "electric ear" which can listen, not for a few miles at the most, but round the whole world. In television man has made for himself an extra eye—an "electric eye" with which he can look across an ocean.

In broadcasting, as you know, the person whose voice has to be sent over the wireless sings or speaks into an instrument called the microphone, which changes the rapidly vibrating sound waves, made in the air by the speaker's voice, into electric currents which vary according to the strength and nature of the sound waves. These electric currents affect the wireless waves, and the wireless waves affect the receiver in your home, where the loud-speaker turns them back once more into sound waves.

First successful "Television" transmitter, made by Mr. Baird, now in South Kensington Museum.

How then can we make a picture or a scene affect the wireless waves? The secret lies in a wonderful instrument which scientists call the photo-electric cell. You will have read of the tiny particles called electrons, tinier even than the atom of which they are a part you will have heard how a stream of these particles moving together in one direction is what we know as an electric current. Now when light waves fall on certain substances, such as the metals sodium and potassium, a stream of electrons is given off from the surface, and this stream, which is really an electric current, varies, of course, with the strength and nature of the light waves themselves.

It would seem, when we look at this apparatus for receiving pictures by wireless telegraphy, that the age of miracles is still at hand. The machine is known as the Fallograph.

HOW A TELEVISION SET BRINGS PICTURES TO OUR HOMES.

The photo-electric cell contains one of these substances. It is put in place of the microphone, a spot of light is made to pass very rapidly up and down over the picture or scene to be broadcast, and the light waves thrown back from this moving spot fall upon the cell. The nature of these light waves differs, of course, according to the shape and colour of the part of the scene from which they come, and so they cause varying electric currents in the photo-electric cell, just as the sound waves do in the microphone. These varying currents affect the chain of wireless waves which is being sent out from the aerials of the broadcasting station, and these in turn fall upon the aerial attached to the receiving set in your home.

What, then, do we attach to our receiving set in place of the loud-speaker to turn the varying wireless waves back into light? The television set, as the instrument is called, is really quite simple, and can be made nowadays at home from parts which can be purchased quite cheaply. It consists in its simplest form of a disc of thin metal punched with thirty tiny holes arranged in the form of a spiral. Behind this is placed a small neon lamp, which works very similarly to some of the bright red advertising signs which we see in our big cities nowadays. The lamp is attached to a suitable wireless receiver, and the disc is revolved by a special tiny electric motor at a speed of 750 turns per minute. Then, if the receiving set is properly "tuned-in" to the wave-length of the station broadcasting, the picture which is being broadcast can be seen by looking through the holes in the revolving disc.

Mr. J. L. Baird, with his assistant, at the transmitting station at Coulsdon, during his experimenting tests.

AN AERIAL HIGH ABOVE THE HOUSE TOPS

A view of the ultra short wave transmitting aerial of the Baird Company's premises in the heart of London.

WHEN PUPPETS PERFORMED FOR THE SCREEN

In the early days of television, when experiments were being made, marionettes, called the Pantopuck Puppets, were made to act in the limited screen space. To-day, real artistes, who are able to give interesting and varied programmes, take the place of those puppets. There are television broadcasts from the B.B.C. late in the evening.

An operator at Broadcasting House, London, is here seen transmitting by television the action of the artistes performing in the studio. The apparatus, The Baird Mirror Drum transmitting set, is shown with sides removed in a later picture.

HOW LONDON SAW A HORSE RACE AT EPSOM

The Baird Television apparatus used at the Metropole Cinema, London, to project the Derby of 1932 by television.

TELEVISION AT HOME AND AT THE B.B.C.

A. Simple Set and the Professional Model

The simple apparatus shown above enables the constructor to build a "Baird Junior" television receiving set. On each side of the lamp are seen blueprints showing the constructor how to build the set.

The B.B.C uses this mirror drum transmitter for their television broadcast. A picture of this in operation was shown above. The mirror drum is seen shining in the front portion of the transmitter above.

HOW MAN SPEAKS ACROSS THE WORLD

In the top left-hand corner the players are performing. The diagram shows how their actions are televised.

A MAN SINGS IN LONDON AND IS WATCHED BY PEOPLE IN DENMARK.

Television is going rapidly ahead. At the time of writing the B.B.C. sends out programmes to which you can "look-in" on four nights a week and there are thousands of enthusiastic "lookers-in," not only in this country, but also in Berlin and as far away as the Canary isles. On one occasion Mr. Carl Brisson, the famous actor, sang songs at Broadcasting House which were received in his native town of Copenhagen in Denmark, and at the same time his image was received on a television screen specially sent out there. Thousands of his fellow-countrymen not only heard but saw him as he sang in London, hundreds of miles away. If you think about this for a little while you will see what a wonderful difference television can make to our lives in the future.

THE INVENTOR "LISTENS IN" TO THE SHAPE OF HIS HAND.

When I was commencing my first experiments with television many years ago, I was struck by the sound which the picture made if the wireless waves were received by a loudspeaker instead of a television receiver. I found that this sound varied in accordance with the object placed in front of the photoelectric cell the sound of a hand, for example, was sharp and clear, whereas the sound of a voice was softer and quite different in character. In fact, with a little practice, I found I could distinguish between different objects by the peculiar sound their "picture" made. My next thought, therefore, was: "Why not, then, make a gramophone record of a picture?" I tried this, and made a record of the sound—and found that it was possible, on playing the record, to turn the sound back into the image. I had, in fact, made the first gramophone record of the picture of a living object.

INVISIBLE RAYS THAT SEE THROUGH A WALL INTO A DARK ROOM.

In the early days, too, it was necessary to use a very powerful light in order to send a picture successfully by wireless, and to avoid this it occurred to me that I might use, not the light waves themselves, but some of the other similar waves which we know exist in the spectrum. For although we cannot see these waves, the photo-electric cell can, and, indeed, I found that by using the long infra-red waves it was possible to send a picture of an object, even though the latter was in complete darkness. In other words, I had found a way of seeing through a wall into a dark room! We have now reached the stage when it is possible to transmit two of our senses—sight and hearing—across the world. The only way we know what is going on is by the information conveyed by the senses. Suppose that in due course the other three senses—taste, touch and smell—can be transmitted, then to all intents and purposes we shall have transmitted ourselves across the world without leaving our arm-chair! Where, indeed, will science lead us if it continues to unfold such marvels as we of the twentieth century have been privileged to see?

THE WONDER OF THE LONG INFRA-RED RAYS OF LIGHT.

In another part of this book other uses of the infra-red rays are described, in the section telling how man has harnessed the forces of Nature to his use. You will there see how the rays may perform wonderful feats, such as catching burglars, or taking photographs through darkness or thick fog. If you watch your newspapers and illustrated journals in the future you will occasionally see fine photographs taken by the infra-red process, and will marvel at the keen eye of these long invisible rays of light.

Mr. Baird is here seen at work experimenting with one of his early television sets that paved the way to his later and more perfect transmitter. The spiral of holes in the revolving disc is seen in the centre of the picture.