Television

SOON after men learned to broadcast sound, inventors wondered if they could also transmit live pictures. To appreciate the challenge, consider how television works today.
First, a TV camera focuses a scene onto a target device that “reads” the picture, similar to the way you read print. However, instead of scanning lines of letters on the page, it scans lines of spots (or pixels) in the picture. It converts what it sees into an electronic video signal that can be transmitted to another place. A receiver then converts the signal back into a live picture.
A Scotsman named John Logie Baird has been credited with being the first to demonstrate a television. When poor health caused him to give up his job as an electrical engineer, he turned to a subject that had interested him since he was a teenager—how to build a machine that could transmit live images.
Baird’s television camera used a disk (a hatbox, at first) perforated by about 30 holes arranged in a spiral. As the disk spun, the holes scanned successive lines of the picture and allowed light to fall on a photoelectric cell. The cell produced a video signal that was transmitted to a receiver. In the receiver the signal was amplified to illuminate a variable light behind a similar spinning disk to reproduce the picture. The challenge was to synchronize the disks. As Baird toiled on the project, he supported himself by shining shoes.
Baird transmitted the first television pictures from one end of his attic to the other on October 2, 1925. The first person ever to appear on TV was a frightened office boy from downstairs, who was pressed into service for half a crown. In 1928, Baird broadcast the first television pictures across the Atlantic. When John Baird arrived in person in New York, the timid Scotsman was acutely embarrassed when he was greeted by a pipe band. He was famous. But was he the first to transmit live pictures?
(Awake 2010)