RADIO TELESCOPES--"The young science of radio astronomy began with investigators simply picking up 'noise' from the sky. But about a year and a half ago a single significant note was discerned through the din. Today listening posts all over the world are tuning in on this high-pitched monotone at 1420 megacycles, and from it they are obtaining a new picture of the universe. The signal carries information about the hydrogen floating in space. One of the first puzzles the new hydrogen telescopes are seeking to unravel is the manner in which our galaxy is rotating. Jan H. Oort, H. C. van de Hulst and C. A. Muller have already discerned a spiral arm structure of hydrogen clouds in the Milky Way system."