Baird's television apparatus, 1926.
© Science Museum / Science & Society Picture Library
John Logie Baird's (1888-1946) mechanical television apparatus was basic but effective. He fitted 30 lenses in a spiral on a cardboard disc cut from a hat box and attached a darning needle as a spindle. This was connected to a motor mounted on an old tea chest which turned the disc. As the disc rotated, each of the lenses scanned a different part of the subject and reflected light, via a charged photo-sensitive cell, to a receiver. This idea was first suggested by the German physicist Paul Nipkow (1860-1940) in 1884 but he did not have the technology to fully realise its potential. During 1929-1935, the BBC transmitted experimental television using Baird's system, and a year later the world's first regular high definition television service began.