Television was not invented by a single inventor, instead many people working together and alone over the years, contributed to the evolution of television. Early inventors attempted to either build a mechanical television system based on the technology of Paul Nipkow's rotating disks; or they attempted to build an electronic television system using a cathode ray tube developed independently in 1907 by English inventor A.A. Campbell-Swinton and Russian scientist Boris Rosing. Electronic television systems worked better and eventually replaced mechanical systems.German, Paul Nipkow developed a rotating-disc technology to transmit pictures over wire in 1884 called the Nipkow disk. Paul Nipkow was the first person to discover television's scanning principle, in which the light intensities of small portions of an image are successively analyzed and transmitted. In the 1920's, John Logie Baird patented the idea of using arrays of transparent rods to transmit images for television. Baird's 30 line images were the first demonstrations of television by reflected light rather than back-lit silhouettes. John Logie Baird based his technology on Paul Nipkow's scanning disc idea and later developments in electronics. Charles Jenkins invented a mechanical television system called radiovision and claimed to have transmitted the earliest moving silhouette images on June 14, 1923. Electronic television is based on the development of the cathode ray tube, which is the picture tube found in modern TV sets. German scientist, Karl Braun invented the cathode ray tube oscilloscope (CRT) in 1897. Russian inventor, Vladimir Zworykin invented an improved cathode-ray tube called the kinescope in 1929. The kinescope tube was sorely needed for television. Zworykin was one of the first to demonstrate a television system with all the features of modern picture tubes. In 1927, Philo Farnsworth was the first inventor to transmit a television image comprised of 60 horizontal lines. The image transmitted was a dollar sign. Farnsworth developed the dissector tube, the basis of all current electronic televisions. He filed for his first television patent in 1927 (#1,773,980). Color TV was by no means a new idea, a German patent in 1904 contained the earliest proposal, while in 1925 Zworykin filed a patent disclosure for an all-electronic color television system. A successful color television system began commercial broadcasting, first authorized by the FCC on December 17, 1953 based on a system invented by RCA.