Electric light be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. Before electric lighting became common in the early 20th century, people used candles, gas lights, oil lamps, and fires. Cornish chemist Humphry Davy developed the first incandescent light in 1802, followed
Royal Watercolour Society well as talks and discussions. The archive and diploma collection is available for research. Current members include Sonia Lawson, Elizabeth Blackadder and David Remfry. The current president Jill Leman was elected in 2017. Royal Watercolour Society The Royal Watercolour Society (originally called the Society of Painters in Water Colours, briefly the Society of Painters in Oil and Watercolours, and for much of its existence the Royal Society of Painters in Water Colours) is an English institution of painters working in watercolours. The Royal Watercolour Society is a centre of excellence for water-based media on paper, which allows for a diverse