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 Philosophical Society of Glasgow Royal Philosophical Society of Glasgow The Royal Philosophical Society of Glasgow is a learned society established in 1802 ""for the improvement of the Arts and Sciences"" in the city of Glasgow, Scotland. It runs a programme of lectures, starting its 217th Series in October 2018. The Society formerly owned a building on Bath Street, but since 1994 has been accommodated within the University of Strathclyde. The Society was founded in 1802 as the Glasgow Philosophical Society by a meeting of sixty people in the former Assembly Rooms, and work began establishing a library collection. The Society was housed in various