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
Proceedings of the Royal Society open access (under Creative Commons license) on payment of an article processing charge. The journal started out in 1800 as the "Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London". The Royal Society published four volumes, from 1800 to 1843. Volumes 5 and 6, which appeared from 1843 to 1854, were called "Abstracts of the Papers Communicated to the Royal Society of London". Starting with volume 7, in 1854, the Proceedings first appeared under the name "Proceedings of the Royal Society of London". Publication of the proceedings in this form continued to volume 75