The Lewis lamp is a type of

light fixture A light fixture (US English), light fitting (UK English), or luminaire is an electrical device containing an electric lamp that provides illumination. All light fixtures have a fixture body and one or more lamps. The lamps may be in sockets fo ...

used in

lighthouse A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mar ...

s. It was invented by

Winslow Lewis Winslow Lewis ( Nathaniel Winslow Lewis; 11 May 1770 – 20 May 1850) was a sea captain, engineer, inventor and contractor active in the construction of many American lighthouses during the first half of the nineteenth century. Life and caree ...

who patented the design in 1810. The primary marketing point of the Lewis lamp was that it used less than half the oil of the prior

oil lamp An oil lamp is a lamp used to produce light continuously for a period of time using an oil-based fuel source. The use of oil lamps began thousands of years ago and continues to this day, although their use is less common in modern times. Th ...

s they replaced. The lamp used a similar design to an

Argand lamp The Argand lamp is a type of oil lamp invented in 1780 by Aimé Argand. Its output is 6 to 10 candelas, brighter than that of earlier lamps. Its more complete combustion of the candle wick and oil than in other lamps required much less frequent ...

, adding a

parabolic reflector A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated ...

behind the lamp and a

magnifying lens A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to cre ...

made from green

bottle glass Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. It has been done in a variety of ways during the history of glass. Glass container ...

in front of the lamp. A similar variant using a parabolic reflector was created by the inventor of the Argand lamp,

Aimé Argand François-Pierre-Amédée Argand, known as Ami Argand (5 July 1750 – 14 or 24 October 1803) was a Genevan physicist and chemist. He invented the Argand lamp, a great improvement on the traditional oil lamp. Early years Francois-Pierre-Améd� ...

. While the Argand variant became widely used by European lighthouses, the Lewis lamp design was selected by the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

for use in American lighthouses. The Lewis lamp would use groups of lamps. The Lewis lamp design proved to have several flaws. To begin, it was really an inferior version of the

. The reflector was made of copper with an interior silver plating to reflect light; however, the thin copper would warp under the heat of the lamps to become more spherical than parabolic. Also, the silver plating was of poor quality and would be scratched off during routine cleanings. Adding to the problem was poor draft for the

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combusti ...

gases, so that soot would build up on the components, decreasing any alleged improvement. In particular, there was a green lens, which ostensibly improved the visibility, but which was prone to being covered in soot. The sooting became such a problem that the lenses were removed from the lamps. The Lewis lamp was the paramount design used in American lighthouses for a number of years. In part, this was due to the federal government's distinct preference for awarding contracts to the lowest bidder. It was also claimed that the Lewis lamp would use substantially less fuel than the Argand lamps, which was true (provided one did not take into account the quality of the illumination). Additionally, there were allegations (never proved) of an untoward relationship between Mr. Lewis and the contracting federal officers. The better view seems to be that the federal officers were not engineers, and were in no way fit to make an evaluation of the quality of the lamps. In fact, Congress eventually established a committee process to review the specifications for the lamps. At a point, the federal officer made claims that the

Fresnel lens A Fresnel lens ( ; ; or ) is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. It has been called "the invention that saved a million ships." The design allows the c ...

was too complicated to be used by members of the lighthouse service. In fact, such concerns turned out to be baseless. In 1852 the Lewis lamps began being replaced with

es, due to the improved viewing distance offered by the Fresnel lens design. This transition was completed by the end of the

American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...

. Fresnel lenses were initially more expensive to install, but they used only one wick and provided better and more focused light, thereby using even less fuel than the Lewis Lamps.

References

* * {{Lighthouses Lighthouse fixtures Oil lamp