How Television Was Invented

in 1926, John Logie Baird built one of the first working television systems. At its heart was a spinning disk with 30 holes arranged in a spiral pattern. As the disk rotated, each hole scanned a different line of an image, breaking it down into a sequence of light and dark signals. These signals were transmitted and used to control a light source on a second synchronized disk at the receiver. As that disk spun in perfect time, it reconstructed the image line by line. The result was a crude, flickering picture, but it proved that moving images could be sent through the air, laying the groundwork for modern television.