The principle of magnetic recording was invented by a Danish telephone engineer called Valdemar Poulsen in 1899. He used an electromagnet to record the tiny electric currents from a telephone to magnetise a steel wire. This recreated tiny currents in the electromagnet when it was replayed. All tape and video recorders still work this way.Episode Contents:Models: A band saw magnetic recorder. Recording a signal on scotch tape covered in rust (FeO^2) particles. A large model of a VCR type head and it's concentrative powers. Illustration of helical scanning.Machines: Great intro scene by Tim and Rex (e.g. slanting cupboards, man eating garbage disposal, rabid mailman, dogfood eating kid, and the oblivious housewife). Rubber band powered beavers.Guests: An early Paulson wire tape recorder. A really impressive German "tapedeck" (c.1930) that used razor sharp steel bands running at high speed under high tension. An airplane black box. A 1940's German tape machine the Tonstreiber (sp?). Ampex VTR's at the BBC. A range of major domestic video formats.Films: The earliest video recordings. A dramatic illustration of generational loss in VHS (re)recordings. Sad adult cartoon characters trying to program their VCR.Extro: Very odd living room scene with mechanically animated knick knacks, spinning stools, tippy stereo components etc.