The educational screen (c1922-c1956])

The News Chat THE PRESS reports seem to show that C. Francis Jenkins of Washing- ton, whose name holds a large place among the pioneers of motion pictures, is no less a pioneer still. He is at present engaged on two tasks of high significance for the development of pictures, a method for sending motion pictures by radio and a speed camera which works at unheard- of speeds. The achievement of the first is more or less remote, although Mr. Jenkins de- clares he knows how it is to be done. About a year will be needed, for the parts needed for the apparatus are not commercially available and must be made in his shop by hand. The camera, however, has been realized and is already producing remarkable re- sults for the U. S. Army. We quote from the press report: "The main principle of the camera is a revolving prismatic ring, a new optical shape in glass, and no shutter is used. This machine takes 100,000 pictures a minute. This is 100 times the speed of a normal speed motion picture camera. A motion which is performed in one second can by Jenkin's invention be spread out over 100 seconds when turned into the film and shown on a screen. "High speed pictures of airplane flights showed what no one had ever been able to see—the bend- ing and warping of the propeller under great pow- ers of the engine. This has been shown in detail by the films, and study of the condition will prob- ably lead to the production of stronger, stirrer blades. "The newest ultra-rapid camera analyzes the high speed motion of a shell as though it were moving at a snail's pace. To the eye the shell, traveling at perhaps 2,500 feet a second, seems to crash into the target almost instantaneously after it is fired. The high speed camera shows it creep- ing with a rotary motion down to the armor plate, wriggling its way into the steel and sending bits of wreckage floating slowly into the air. "The golf club shaft is shown by the camera actually to bend forward as it strikes the ball. That the stick did this was suspected by some players, but there was no way of proving the point. The camera shows that as the club is brought down to the ball the force of the drive bends the shaft forward. The head of the club lags behind from the force of the stroke. But at the instant the clul head contacts with the ball the bend in the shaf is reversed. "This camera is for scientific purposes. Just at a very high-powered microscope is necessary fa some exacting laboratory work, so the ultra-rapid camera, with a prospect of attaining 200,000 pici tures a minute, will have its place in scientifii search." AERIAL PHOTOGRAPHY is be coming steadily more useful and it a great variety of ways. The mapping oi the city of Washington, for use by the city engineer for city planning purposes., is being made easier and more effective by the camera and aeroplane. A special instrument has been developed which works at a height of three miles where the flight is steadier and is focused accu- rately through the bottom of the machine. This camera brings down a hundred fee( of film which gives absolutely trust- worthy data on the area covered. Under a strong glass even the number of autos parked in a given square can be accu- rately counted. This sort of work prom- ises to become so extensive for landscape and engineering purposes that a special notice has been issued for volunteers to enter the government service in this line. A French hydrographer has secured remarkable results with the air camera in mapping the harbor of Brest. It was discovered during the war that objects far below the surface of the water were visible from a height and many sub- marines were located in this fashion. Now features of river bottoms appear to a depth of forty or fifty feet, yielding a vasl deal of information instantly which would have required long labor by the old sounding methods. The U. S. Geological Survey is making extensive use of the same method ir charting the Atlantic Coast. Maps of the vicinity of Cape Charles, Virginia, have '424