Electric lamps, past and present

The article traces the story of the electric lamp, which began when, in 1810, Davy demonstrated the now legendary `bright carbon arc' that led, in 1850, to the production of practical arc lamps. Because of the `powerful' intensity of the arc lamp, there was a demand for `the subdivision of light' and this culminated, in 1879, in the invention of the incandescent filament lamp. Gaseous and vapour discharge lamp research began around 1850 and practical lamps were available in the early 1900s. There were carbon dioxide, nitrogen and neon filled tubes giving `daylight', `sunlight' and red light emissions, respectively. Also, and still available, there were high-voltage, mercury vapour, cold-cathode fluorescent tubes. Following research in the early 1930s mains voltage, high- and low-pressure mercury and sodium vapour lamps have been under constant development and they are widely used today. Fluorescent lamps, introduced in 1938, are regularly being improved in design and among the latest are compact energy saving types that are ideally suited, as direct replacements, for GLS lamps. The recent announcement of the QL induction lighting system is the latest milestone in `electric light' invention