What is a Lighthouse?

A lighthouse is s building that was made to guide ships. The most important part of a lighthouse is the light that it casts at night. Almost everything else at the lighthouse is designed to help keep the light as bright and visible as possible.

Sometimes lighthouses guide ships to a port or harbor. Other times they guide ships away from a hazard. Sometimes they do both.

At night, lighthouses guide ships with their light. Mariners can tell what light they are seeing by its characteristic. All ships have a book, called a Light List, that tells them the characteristics of lighthouses. When a mariner sees a light, he can look it up in the Light List to see what one it is. Off the South Shore of Long Island, if  mariner saw a white light flashing every seven-and-one-half seconds, he could look it up and find out that it is the Fire Island Lighthouse. He could also see in the book what lighthouse he should expect to see next, depending on which way he is traveling.

During the day, lighthouses guide ships with a daymark. A lighthouse's daymark is simply its size, shape and color. Using Fire Island as an example again, its daymark is a tall, round tower with two black stripes and two white stripes. Daymarks are also listed in the Light List.

Basic American Lighthouse History

In early American history, shipping was very important. Ships and boats were the major way to transport people and cargo at the time. Most of the American colonies had long coasts, and relied on sea trade to get many of the supplies they needed.

There were many hazards. to early shipping: rocks, sand bars, shallow water and other hazards made shipping dangerous. In those days, if a shipload of cargo was lost, it could cause great hardship for the colonists. And lives were often lost aboard the ships when they wrecked.

Before lighthouses were built, some people used lanterns or fires on land to help ships navigate at night. But the same system was not used everywhere, and could cause confusion for mariners from another area.

The first "real" lighthouse built in America was in 1716 on Little Brewster Island near Boston. About ten more were built up to 1776. One of these was the Sandy Hook Lighthouse in New Jersey. It was built in 1764, and is still in operation. -- the oldest operating lighthouse in the United States.

In 1776, the American colonies declared independence from Great Britain, and spent the next seven years fighting a war to become truly independent. After the war, the thirteen colonies formed a government based on a document call the Articles of Confederation. This was the first government of the United States of America. The government under the Articles of Confederation was not strong, and there were many problems in the new country, so many of the nation's best leaders got together in 1787 to discuss a better form of government. They designed a new government, based on the "Constitution for the United States of America." The Constitution, and its new government, became official on June 21, 1788. This is the same government we still have today.

During the early sessions of the new Congress, the subject of lighthouses was discussed. It was eventually decided, in a bill called H.R. 12, or the Lighthouses Act of 1789, to make the building and maintenance of lighthouses the responsibility of the new federal government. The federal government has controlled American lighthouses ever since.

Although the lighthouses were under federal control, the specific government department that ran them has changed many times. Some of the more notable periods are listed below:

From 1820 to 1852, America's lighthouses were run by the Fifth Auditor of the Treasury. His name was Stephen Pleasanton. During the War of 1812, as a clerk in Washington, D.C., he saved some of the nation's early important documents by taking them from the city before the British burned it. As Superintendent of Lighthouses, he was much more controversial. The lighthouses built in America during this period were not built very well and had bad lights. Mr. Pleasanton did not like to spend money, even on improvements in technology, administration, or building techniques. There were several studies done of America's lighthouses during this period, usually prompted by complaints from mariners. The final report, in 1851, resulted in the creation of the Light House Board.

From 1852 to 1910, the Light House Board ran the lighthouses in the United States. This new organization was composed mostly of military people with experience in engineering and other important areas. The Board's improvements in administration and technology made America's lighthouse system the best in the world, with powerful lights held in strong lighthouses. Many of the lighthouses from this period are still standing and still serving mariners. The Light House Board also improved the selection, training, and administration of lighthouse keepers. American lighthouse keepers became responsible for keeping their stations very clean, running them well, and keeping strict records.

The Light House Board was disbanded in 1910 and the lighthouses were once again put under the control of a single civilian head. The administration stayed that way until 1939, when the Lighthouse Service was made part of the US Coast Guard. Lighthouses in America have been under the control of the Coast Guard ever since.

Because of advancements in the technology of maritime navigation, many people do not feel that lighthouses are necessary anymore. As a result, the government does not allow for much money to maintain them. The support of communities, especially nonprofit preservation groups, is now needed to preserve America's lighthouses and the history that they represent.

Lighthouse Terms

These are words you'll sometimes see when reading about lighthouses.
Most of these definitions come from my friend Bob's book, Long Island's Lighthouses: Past and Present.


Appropriation – An act of legislation authorizing the expenditure of a designated amount of public funds for a specific purpose.

Argand lamp – A lamp using a circular hollow wick and glass chimney. Patented in 1784 by Swiss chemist and inventor Aime Argand (1750-1803). Winslow Lewis’ lamps were based on Argand’s design.

Automated lighthouse – A lighthouse that has been modified with technological advances so that it no longer requires the services of a full-time keeper.

Bell tower – A tower on which a fog bell is hung. The elevation afforded by the tower allows the bell to be heard further.

Bivalve lens – A type of Fresnel lens  that consisted of two bull’s-eye style lenses, one mounted on each side of the lamp. Also known as a clamshell lens, because of its appearance, or a lightning lens, because of its powerful flash. Montauk Point’s 1903 bivalve lens now resides in its museum.

Brig – A sailing ship with two masts, both of them square-rigged.

Buoy – A floating minor aid to navigation, moored to the seabed. Some have been designed with lights, sirens, gongs, or bells to make them easier to locate at night or in bad weather.

Butt – A large barrel, of approximately 126 gallons volume, used to hold oil.

Caisson base – A watertight foundation that extends beneath the water line.

Candlepower – a measure of the intensity of light.

Characteristic – The identifying features of a light, such as its color and flashing sequence.

Cistern – A tank for storing rainwater. These were often built into the cellars of keepers’ quarters.

Clockworks – The mechanism used to operate machinery, such as a rotating lens or a fog bell. Early versions were wound by hand.

Daymark – The size, shape, and markings that identify a lighthouse in the daytime.

Diaphone – A fog signal that makes a two-tone sound, as in the well-known “BEEEE-OOOOH” sound.

Flotsam and Jetsam – Objects found floating or washed ashore.

Fresnel lens – A type of lens developed in the 1820s by French physicist Augustin Jean Fresnel. Its power and efficiency allowed for the use of one lamp in place of many, thereby decreasing the consumption of lamp oil. These lenses came into general use in the United States after 1852. Seven sizes, or “orders,” were commonly used (First, Second, Third, Third-and-One-Half, Fourth, Fifth and Sixth). The only active Fresnel lens on Long Island is at Eaton’s Neck. Others are on display at Fire Island, Montauk Point, Horton Point, and the East End Seaport Museum.

Harbor – A body of water that provides safety for ships.

Illuminating apparatus – The means by which light is produced and sent out from a lighthouse. These could include oil lamps and reflectors; an oil lamp and Fresnel lens; a modern electric light; and others.

Incandescent Oil Vapor (IOV) lamp – A type of lamp that used pressurized and vaporized oil burned in a mantle. These powerful lamps were the last oil-fueled lighthouse lamps.

Lantern – The glass-enclosed part of the lighthouse, where the illuminating apparatus is mounted.

Lard oil – A form of animal-based oil used as a lamp fuel in the mid- to late 1800s. It was cheaper than whale oil, but produced acrid fumes and often congealed in cold weather.

Lewis, Winslow (1770–1850) – The man whose lamp and reflector designs were used in American lighthouses from the early to mid 1800s. The origins and construction of his lamps and reflectors were the subject of much criticism.

Light List –  A book for mariners that lists lighthouses, buoys, and other aids to navigation. This list helps mariners determine where they are.


Light vessel – A ship with one or more masts, on top of which one or more lights is mounted. Also known as lightships, these vessels were anchored at offshore locations where a lighthouse was needed but could not be built. Light vessels generally also included a fog signal. There are no longer any lightships on active duty in the U.S.

Mariner – Someone who navigates, or helps to navigate, a ship; a sailor.

Mineral Oil – Kerosene; A thin distilled oil used for American lighthouse illumination in the late 1800s and early 1900s.

Oil house – An auxiliary building used to store oil. These were built at American lighthouses with the introduction of mineral oil, which was much more volatile than previous lamp fuels. On Long Island, most oil houses were built between 1902 and 1904, and were made of brick.

Order – The size of a Fresnel lens. A First Order lens was the largest; a Sixth Order was the smallest.

Pleasanton, Stephen (1777–1855) – Superintendent of Lighthouse for the U.S. from 1820 to 1852, as Fifth Auditor of the Treasury. As a clerk in Washington, D.C. in 1814, Pleasanton saved the Declaration of Independence and other important early American documents by taking them away from the city before it was burned by the British.

Port – A city or town that has facilities for loading and unloading ships.

Radiobeacon – An aid to navigation that consists of a radio transmitter sending out distinctive signals.

Range lights – A pair of separate lights used in conjunction with each other for navigation. Generally used to indicate a channel.

Reflector – A highly polished parabolic metal surface placed around a lamp to direct the lamp’s rays in a particular direction. These were used in the U.S. in the early- to mid 1800s.

Riprap – Large, irregularly shaped rocks piled loosely to protect the foundation of a lighthouse.

Schooner – A sailing vessel with at least two masts, fore-and-aft rigged.

Screwpile – A type of lighthouse foundation that used multiple iron piles screwed into the seabed and braced together. These foundations were rare in northern waters because of their susceptibility to ice floes.

Shoal – A shallow area in a body of water.

Shipwreck – The destruction of a ship by collision, or wind and waves. Also, a ship that has been destroyed in such a way.

Siren – A fog signal that used compressed air or steam through a rotating perforated disk to create a loud sound.

Skeleton tower – A tower made of exposed metal tubing.

Sloop – A single-masted, fore-and-aft rigged sailing vessel.

Soapstone – A soft rock, composed mostly of mineral talc.

Spider lamp – An early form of oil lamp that used multiple wicks from a single source of oil. In some designs, the wicks looked like the legs of spiders.

Trumpet – A fog signal consisting of a long metal tube, flared at the end, through which air is forced to create a loud sound.

Watch room – The room in a lighthouse where the lighthouse keeper stays when he is working ("on watch").

Whale oil – The fuel used to power Long Island’s lights until the mid 1800s. The rapid rise of its price led to its replacement with cheaper oils, mostly lard oil.

Whitewash – A mixture of lime and water, sometimes with additives, used to whiten lighthouse towers, walls, fences, or other structures.

Wick, concentric – A series of two to five hollow wicks, set one inside the other. This created a brighter flame.

Wick, hollow – A wick that formed a tube. Its invention improved the power from an oil lamp by allowing air to flow inside the flame, as well as outside of it.

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