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
Medal of the Royal Numismatic Society Medal of the Royal Numismatic Society The Medal of the Royal Numismatic Society was first awarded in 1883. It is awarded by the Royal Numismatic Society and is one of the highest markers of recognition given to numismatists. The President and Council award the Medal annually to an "individual highly distinguished for services to Numismatic Science". In recent years the Medallist has been invited to receive the medal in person and to give a lecture, usually at the Society's December Meeting. Sir John Evans gave the dies for the original silver medal to the Society in 1883. The current medal