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
Fellow of the Royal Society of us shall signify to the President under our hands, that we desire to withdraw from the Society, we shall be free from this Obligation for the future". Since 2014, portraits of Fellows at the admissions ceremony have been published without copyright restrictions in Wikimedia Commons under a more permissive Creative Commons license which allows wider re-use. In addition to the main Fellowships of the Royal Society (FRS, ForMemRS & HonFRS), other fellowships are available which are applied for by individuals, rather than through election. Holders of these fellowships are known as Royal Society Research Fellows. In addition to the