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 Society ForMemRS (Foreign Member of the Royal Society). The Royal Society President is Venkatraman Ramakrishnan, who took up the post on 30 November 2015. Since 1967, the society has been based at 6–9 Carlton House Terrace, a Grade I listed building in central London which was previously used by the Embassy of Germany, London. The Invisible College has been described as a precursor group to the Royal Society of London, consisting of a number of natural philosophers around Robert Boyle. The concept of "invisible college" is mentioned in German Rosicrucian pamphlets in the early 17th century. Ben Jonson in England referenced