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Show U. S. Television Hits New High In Development Broadcasts Now on Regular Regu-lar Schedule From New York. Prepared by National Geographic Society, Washington, D. C WNU Service. Television broadcasts in the United States are now on regular schedule and manufacturers manu-facturers have begun the wholesale production of receiving re-ceiving sets as the American public begins to realize the value of this new form of education and entertainment. The inaugural telecast in this country coun-try was produced on April 30, 1939, when President Roosevelt opened the New York World's fair. Since then television has launched into the air an eye-and-ear-witness impression of the king and queen of England visiting the fair, of a canary circus, of a baseball game, a boxing bout, a ballet, a swimming contest, a marionette show, a six-day six-day bicycle race, the docking of the new liner Mauretania, a track meet, and a fashion parade. Experts point out that important differences between radio and its sister science of long-distance seeing see-ing place difficulties in the way of a nation-wide television network to parallel radio hookups. Yet the American people who promptly invite in-vite each new scientific marvel into the living room, are showing a lively live-ly interest in television, although the majority of them are still beyond the reach of current programs. Twenty Tubes to Set. Television has put into American homes the most complicated instrument instru-ment yet devised for popular use a radio set plus. It has about 20 r T , it n MASS PRODUCTION. With television sets now on sale at regular retail prices, manufacturers manufac-turers have begun assembly line production of receiving units. This picture shows standard instruments in-struments in the process of being assembled. tubes. One of them is the giant cathode-ray vacuum tube 27 inches long that creates the television picture pic-ture on the top of its flattened bulb by means of a tiny "pencil" of streaming electrons. It has sound controls for volume and high and low pitch adjustments. It has sight controls for focus, speed, size, and centering adjustments of the picture. pic-ture. Television has also put into circulation circu-lation a new vocabulary telecast, to correspond to broadcast; video frequencies, fre-quencies, as differentiated from the sound wave frequencies of radio; "ike," instead of "mike," for the Iconoscope, which corresponds to radio's microphone. Ultra-Short Waves Used. From the giant antenna on the Empire State building a quarter of a mile above the earth, the radio waves that carry the sound part of the program are launched into the air exactly as in ordinary shortwave short-wave radio transmitting. The ultrashort ultra-short waves that carry the visual part are of such high frequencies that instead of kilocycles (thousand cycles) they are listed in megacycles mega-cycles (million cycles). Sound, even that of a symphony orchestra, usually usual-ly is transmitted in a group of frequencies fre-quencies not more than 5,000 cycles wide. But a good television image requires frequencies jumping from 30 to 4.000,000 cycles within a second's sec-ond's time. In addition, two series of waves synchronizing impulses must be broadcast to keep receiver and transmitter in perfect step. A lag of less than one-millionth of a second in the receiving set would make inperfect television pictures. From the outset it is apparent that television is at least three times as complicated as radio. An added difficulty is the fact that the very high frequency television waves do not bounce between the earth and a reflecting layer in the sky as do the longer waves used in sound broadcasting. Such repeated repeat-ed reflection permits radio waves to reach far over the horizon in fact to follow the curvature of the earth completely around the globe. Television Tele-vision waves shoot straight off through the reflecting layer into BEAUTY MAKEUP. The young lady clad in war paint is not preparing for a part in a horror thriller but is merely "making-up" for a regular television tele-vision broadcast. Special skill in the use of rouge and paint is required to give good picture reproduction in telecasts. outer space and are lost. They usually usu-ally cannot be captured by television televi-sion sets much beyond the horizon. 1 Draw a straight line, representing the path of television waves, from any point on the earth's surface, and you will recognize that they soon part company with the curving earth. To be sure of "viewing in" on a television program, therefore, a receiving set should be close enough to the transmitter to be within the television horizon. From the lofty antenna on the Empire State building, sets within a radius of 55 miles regularly receive the program, as well as some sets from 125 to 150 miles away. Resembles Ordinary Radio. Outwardly the television receiving set most generally in use resembles a large radio console with an extra row of buttons and a propped-up lid. The television image a vision indeed appears beneath the lid, where the televised scene in perfect miniature comes to life on a glass plate 8 by 10 inches. Presiding genius of the television receiving set is the 27-inch funnel-shaped funnel-shaped vacuum tube, standing upright up-right like a lily. As a loud speaker translates silent radio waves into sound, this tube' translates invisible waves into a visible picture. Its narrow stem contains an electron gun primed with cathode-ray ammunition. am-munition. Its broad top is capped with a glass plate curved to shield the vacuum within from the atmospheric atmos-pheric pressure above. The under surface of the glass is coated with a chemical mixture, zinc sulfide, which is capable of fluorescing (emitting light) when struck by electrons. elec-trons. An electrical impulse from the transmitter modulates the beam, or ray, fired from the electron gun; when the electrons hit the fluorescent fluores-cent surface the glass shows a tiny point of light which is bright or dull according to the intensity of the modulated beam of electrons. Two Miles a Second. The electron stream is shot in machine-gun sequence across the face of the plate from left to right at a speed of two miles a second; then it zips back to the left at double quick time and repeats the bombardment. bom-bardment. With about 500 "shots" in a row, it makes 441 trips from left to right to fill in the picture completely from top to bottom. This action is controlled by electro-magnetic force. (Whether each tiny "shot" of the electron bombardment p - Hi J - j U , Zip-"" ,4 i im cvL- ' I AID IN CRIME WAR. Here is a test telecast being made to determine the value of television in criminal identification by reproducing re-producing fingerprints. Officials claim that in cases where speed is important, fingerprints could be broadcast to operatives away from police headquarters, eliminating elimi-nating the dulay caused by mailing mail-ing the prints to a central bureau. registers as light or shadow is determined de-termined by what the television camera has revealed of the object being televised.) The 441 scanning lines for each picture are completed too quickly for the human eye to detect the electron pencil in action, and the resultant illusion is comparable com-parable to the illusion obtained from the movies, which project 24 still pictures per second to create the impression im-pression of movement. The television televi-sion image is created by a rapid succession of 30 complete pictures per second. |