The production of light is probably the second oldest technology of humankind, coming about a million years after the development of stone tools. Prehistoric peoples used fire for heating and cooking, but also for the production of light. The simplest lighting device was the torch.
Lighting devices became more practical with the introduction of the oil lamp. In its simplest form, the oil lamp consists of a small receptacle with a groove or nozzle in which a wick burns. Lamps of this design have been found in caves dating from the end of the Old Stone Age.
The Romans developed a form of lamp that has no container the candle. Candles, made from tallow, beeswax, and bayberry wax, continued to be a major source of illumination through the 18th century.
Oil lamps became more sophisticated, but the basic principle of a wick and an inflammable liquid continued in use for thousands of years. Whale oil was used during the 19th century until methods were found to produce the light oil kerosene from petroleum. Kerosene lamps were the main source of light in rural parts of the United States until rural electrification in the 1930s and 1940s. The better kerosene lamps used a mantle instead of a wick; the mantle is a treated net that absorbs gas and glows with a bright, white light when lit. Campers today often use lamps that combine a volatile fuel with a mantle.
At the end of the 18th century gas light was introduced in cities. Natural gas, or more commonly gas made from wood or coal, was piped to street lamps and into houses. As a result, much of the 19th century is known as the Gaslight Era.
In 1808 Humphry Davy developed the arc light, which eventually was put to several uses. Although the electric arc between two carbon electrodes produced a brilliant light, it generated large amounts of smoke and heat. Furthermore, the carbon was gradually consumed, so the distance between the electrodes needed to be shortened frequently to maintain the proper amount of gap. Despite these problems, arc lamps during the 19th century were used in public places in Paris and London and especially in lighthouses. However, they did not become the basis of household lighting.
The greatest breakthrough in lighting came in 1879 with the invention of the filament lamp, or incandescent bulb, by Edison in the United States and Joseph Swan in England. It had been known since 1838 that an electric current through a thin filament of carbon in a vacuum produces light. The achievement of Edison and Swan was to develop this method into a practical incandescent lamp that could burn for 40 or more hours. The Gaslight Era did not last long after the electric lamp was invented, for it quickly displaced gas.
The fluorescent lamp was developed in the 1930s. It consists of a tube that is coated on the inside with a fluorescent material and filled with mercury vapor. An electric discharge in the vapor produces ultraviolet light, which in turn causes the coating to fluoresce. By adjusting the coating, fluorescent lamps can be produced to give light with wavelengths that are closer to natural sunlight than can be achieved with the incandescent bulb. The lamps also operate on less electric power. Despite these advantages, fluorescent lamps have failed to replace incandescent bulbs in most homes, partly because the initial expense is greater for a bulb and partly because the lights most available seem to many to produce a harsh light.
The light of the future is expected to be electronic rather than electric. Arrays of light-emitting diodes are used for many purposes already that were once the province of incandescent bulbs.