Practical Television

There is an emotion of mixed awe and delight at his inventions that keeps the eyes of every scientist naive and young. Three amiable groups in three separate homes in Schenectady, N. Y. were so moved last week. A few blocks away in a research laboratory of the General Electric Co. a fourth group tingled sympathetically. In the laboratory was a television sending set; in the homes were television receiving sets. In the laboratory broadcasters moved, talked, sang, and in regimented waves their actions and sounds gambolled over the radio to the sight & hearing of the home audiences. Television, last spring a Bell Telephone laboratory accomplishment, last week was a General Electric and Radio Corporation of America practical device.

Sending Set. This consists of: 1) an arc light of brilliant and steady glow which throws a beam of light through 48 apertures arranged spirally in 2) a large disc that revolves 18 times a second. The light thus brushes speedily across an object or performer and is reflected back upon the third important element of the device--photo-electric cells. The reflected light modifies the electro-magnetic waves passing through the tubes. With light waves rapidly translated into electro-magnetic waves, there remains no problem of sending the electro-magnetic waves through the air. Radio transmission, which changes sound waves (also a part of the machine) into electro-magnetic waves has solved that. The sight & sound despatched at Schenectady last week traveled on wave lengths of 37.8 meters.

The Inventors. A shy man, pallid from years spent indoors over books and work tables, attended the demonstrations in Schenectady last week. He was Daniel McFarlan Moore, 58, known well wherever electrical technicians congregate, but little elsewhere. Graduated from Lehigh University in 1889 he at once found work with Thomas Alva Edison's Edison Co. Later he organized his own light and electric companies and, after 18 years, sold them to General Electric. Four years ago he invented vacuum bulbs used in telephotography (sending still pictures by electricity or radio); three years ago he improved the bulb so that it would transmit moving pictures. His present researches seek to make lamps that will give light without heat. Towards that goal he has made some progress. On his inventions the Government has granted 100 patents. His home is at East Orange, N. J., not far from that of Mr. Edison.

Ernst Frederik Werner Alexanderson, mechanical as well as electrical genius, took Mr. Moore's neon tube and made it the heart of television devices on which he had been experimenting for half a dozen years. The rotating disc with its holes arranged in spirals is his, as is the method synchronizing the television sending and receiving sets. Transoceanic radio and radio telephony are possible because he invented the Alexanderson high frequency alternator. To buy that invention and thus to prevent the British Marconi Co. from acquiring it, the Radio Corporation of America was created. He is R. C. A.'s chief consulting engineer. One of the receiving sets used last week stood in the corner of a ground floor room in his home at Schenectady. He is 50 years old, has 150 patents to his credit.

Sales. David Sarnoff, 37, vice president & general manager of R. C. A., is in the position of a man who has something that customers clamor to buy but which he knows is not perfect enough to sell under his name. "In five years," said he, "television will be an art and an industry. But I cannot promise any date at which we can make the sale of television receiving sets. Generally there remains considerable testing & experimenting to be done."

Receiving Set. The television receiving set contains practically the same elements as the sending set, plus an all-important invention--a Moore tube. This tube is similar to a radio vacuum tube but filled with neon gas which glows pinkly when current passes through the tube. Light in the tube can vary in intensity 1,000,000 times a second. As in ordinary radio receivers the waves coming into the television receiver are amplified. Then instead of being shunted through only a loud speaker, they are passed through both a loud speaker and the Moore neon tube. The loud speaker changes part of the incoming waves into sound, the tube another part into light. That light, flickering too fast for analysis by the unaided eye, shines against a disc like the disc in the laboratory--with 48 holes arranged spirally and rotating 18 times a second. The swiftly turning holes interrupt the tube flickers just enough for the human eye to receive visual impressions. Observers see pinkishly as well as hear loudly just what is happening at the sending station.

De Forest Doubts. Said Dr. Lee De Forest, inventor of the three-element vacuum tube: "I do not think that any marked advance has been made in the Alexanderson television apparatus, except in the synchronization system. I think that television will never be practical in the home, due to the fact that the present methods require large rotating parts operated by a motor. The difficulty is that the operator at the receiving end must constantly regulate a little knob or dial, to prevent the picture from becoming distorted. We are still a million miles away from the application of television on a large theatre screen, because eighteen inches today constitutes approximately the largest television screen in use. A new system must be developed, based on another branch of physics, which will get away from heavy and rotating parts before seeing by radio can be made practical for private use."