NOTHING NEW UNDER THE SUN (ALMOST)
31st October, 1904: A new device which acts like a valve for electricity, allowing it to flow in one direction but not another, will have a big future in wireless. Among other uses it can replace the unreliable crystal and cat’s-whisker combination which makes the operation of many wireless receivers so frustrating. Invented by John Fleming, of London University, it looks a bit like an electric light bulb. A heated filament boils off negative electric particles, which are collected by a positively charged plate.