At the heart of Farnsworth’s system was something called an image-dissector camera, which allowed him to paint (as it were) pictures across a screen by scanning them in electronically one line at a time—and to do it so quickly that the eye was fooled into thinking it was seeing a series of continuous images. Even in its earliest versions Farnsworth’s system had 150 lines, giving it a crispness that no mechanical system could ever achieve.
