| Show Us S television hits new high in development broadcasts now on regular Selie schedule dule from new york pre prepared ared by national geographic society washington ashl agton D C SL service ice television broadcasts in the united states are now on regular schedule and manufacturers rs have begun the wholesale production of receiving sets as the american public begins to realize the value of this new form of education and entertainment the inaugural telecast in this country was produced on april 30 1939 when president roosevelt opened the new york worlds 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 ipg contest a marionette show a six six day bicycle race the docking of the new liner a track meet and a fashion parade experts point out that important differences between radio and its 47 31 I 1 t fl A 4 1 MASS production with television sets now flow on sale at regular retail prices manufacturers have begun assembly line production of receiving units this picture shows standard instruments in the process of being assembled sister science of long distance seeing place difficulties in the way of a nationwide nation wide television network to parallel radio hookups yet the american people who promptly invite each new scientific marvel into the living room are showing a lively interest in television although the majority of them are still beyond the reach of current programs television has put into american homes the most complicated instrument yet devised for popular use a radio set plus it has about 20 tubes one of them is the giant cathode ray vacuum tube 27 inches long that creates the television picture 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 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 short wave radio transmitting the waves that carry the visual part are of such high frequencies that instead of kilocycles kilo cycles thousand cycles they are listed in mega cycles million cycles sound even that of a symphony orchestra usually is transmitted in a group of frequencies quen cies not more than cycles wide but a good television image requires frequencies jumping from 30 to cycles within a seconds time in addition two series of waves synchronizing impulses must be broadcast to keep receiver and transmitter in perfect step 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 reflection permits radio waves to reach far over the horizon in fact to follow the curvature of the earth completely around the globe television waves shoot straight os 0 through the reflecting layer into I 1 I 1 A X al 0 9 al I 1 1 4 BEAUTY AIA MAKEUP KEUP the young lady clad in ivar paint is not preparing for a part in a horror thriller but is merely making up for a regular television broadcast special skill in the use of rouge and paint is required to give good picture reproduction in telecasts tele casts outer space and are lost they usually cannot be captured by television sets much beyond the horizon draw a straight line representing the path of television waves from any point on the earths 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 to miles away resembles ordinary radio outwardly the television vision 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 vacuum tube standing upright 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 its broad top is capped with a glass plate curved to shield the vacuum within from the atmospheric 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 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 bar dment with about shots in a row it makes trips from left to right to fill in the picture completely from top to bottom this action is controlled by electro mag betic force whether each tiny shot of the electron bombardment J v p X q s AID IN CRIME WAR here is a test telecast being made to d determine eter the value of television in criminal identification by reproducing fingerprints registers as light or shadow is determined ter mined by what the television camera has revealed of the object being televised the scanning lines for each picture are completed toe toc quickly for the human eye to detect the electron pencil in action and the resultant illusion is is comparable to the illusion obtained from tha ahn movies which project 24 still pit pictures tures per second to create the impression py esson of movement the television wn ima image ge is created by a rapid succession uc cession of 30 complete pictures per second |
