Editing Lighthouse (section)

==Building==
===Components===
[[File:Lighthouse lantern room with Fresnel lens.png|thumb|Lighthouse lantern room from mid-1800s]]

While lighthouse buildings differ depending on the location and purpose, they tend to have common components.

A light station comprises the lighthouse tower and all outbuildings, such as the keeper's living quarters, fuel house, boathouse, and [[Foghorn|fog-signaling]] building. The Lighthouse itself consists of a tower structure supporting the lantern room where the light operates.

The lantern room is the glassed-in housing at the top of a lighthouse tower containing the lamp and lens. Its glass storm panes are supported by metal [[muntin]]s (glazing bars) running vertically or diagonally. At the top of the lantern room is a stormproof ventilator designed to remove the smoke of the lamps and the heat that builds in the glass enclosure. A [[lightning rod]] and grounding system connected to the metal cupola roof provides a safe conduit for any lightning strikes.

Immediately beneath the lantern room is usually a Watch Room or Service Room where fuel and other supplies were kept and where the keeper prepared the lanterns for the night and often stood watch. The clockworks (for rotating the lenses) were also located there. On a lighthouse tower, an open platform called the gallery is often located outside the watch room (called the Main Gallery) or Lantern Room (Lantern Gallery). This was mainly used for cleaning the outside of the windows of the Lantern Room.<ref>{{cite web |url=http://www.nps.gov/history/maritime/ltcomp.htm |title=Light Station Components |publisher=nps.gov }}</ref>

Lighthouses near to each other that are similar in shape are often painted in a unique pattern so they can easily be recognized during daylight, a marking known as a [[daymark]]. The black and white barber pole spiral pattern of [[Cape Hatteras Lighthouse]] is one example. [[Race Rocks Light]] in western Canada is painted in horizontal black and white bands to stand out against the horizon.

===Design===

For effectiveness, the lamp must be high enough to be seen before the danger is reached by a mariner. The minimum height is calculated by trigonometry (see [[Horizon#Distance to the horizon|Distance to the horizon]]) as <math alt="D is 1.22 times the square root of H"> D = 1.22 \sqrt {H} </math>, where ''H'' is the height above water in feet, and ''D'' is the distance from the lighthouse to the horizon in nautical miles, the '''lighthouse range'''.<ref>{{Cite web |title=How to Calculate the Distance to the Horizon |url=https://www.boatsafe.com/calculate-distance-horizon/}}</ref>

Where dangerous shoals are located far off a flat sandy beach, the prototypical tall masonry coastal lighthouse is constructed to assist the navigator making a landfall after an ocean crossing.  Often these are cylindrical to reduce the effect of wind on a tall structure, such as [[Cape May Light]]. Smaller versions of this design are often used as harbor lights to mark the entrance into a harbor, such as [[New London Harbor Light]].

Where a tall cliff exists, a smaller structure may be placed on top such as at [[Horton Point Light]]. Sometimes, such a location can be too high, for example<!-- Should this be "too high; for example,"? --> along the west coast of the United States, where frequent low clouds can obscure the light. In these cases, lighthouses are placed below the clifftop to ensure that they can still be seen at the surface during periods of fog or low clouds, as at [[Point Reyes Lighthouse]]. Another example is in [[San Diego]], [[California]]: the [[Old Point Loma lighthouse]] was too high up and often obscured by fog, so it was replaced in 1891 with a lower lighthouse, [[New Point Loma lighthouse]].{{Citation needed paragraph|date=May 2021}}

As technology advanced, prefabricated skeletal iron or steel structures tended to be used for lighthouses constructed in the 20th century. These often have a narrow cylindrical core surrounded by an open lattice work bracing, such as [[Finns Point Range Light]].

Sometimes a lighthouse needs to be constructed in the water itself.  Wave-washed lighthouses are masonry structures constructed to withstand water impact, such as [[Eddystone Lighthouse]] in Britain and the [[St. George Reef Light]] of California.  In shallower bays, [[Screw-pile lighthouse]] ironwork structures are screwed into the seabed and a low wooden structure is placed above the open framework, such as [[Thomas Point Shoal Lighthouse]]. As screw piles can be disrupted by ice, steel caisson lighthouses such as [[Orient Point Light]] are used in cold climates.  [[Orient Long Beach Bar Light]] (Bug Light) is a blend of a screw pile light that was converted to a caisson light because of the threat of ice damage.<ref>{{cite web|url=http://www.nps.gov/history/maritime/constype/constype.htm|title=Maritime Heritage Program - National Park Service|access-date=6 April 2017}}</ref> Skeletal iron towers with screw-pile foundations were built on the [[Florida Reef#Shipwrecks and lighthouses|Florida Reef]] along the Florida Keys, beginning with the [[Carysfort Reef Light]] in 1852.<ref>{{Cite book|last=Dean|first=Love|title=Reef Lights|publisher=The Historic Key West Preservation Board|year=1982|isbn=0-943528-03-8|location=Key West, Florida}}</ref>

In waters too deep for a conventional structure, a [[Lightvessel|lightship]] might be used instead of a lighthouse, such as the former [[United States lightship Columbia (WLV-604)|lightship ''Columbia'']].  Most of these have now been replaced by fixed light platforms (such as [[Ambrose Light]]) similar to those used for offshore [[oil exploration]].<ref name="nps">{{Cite web|url=https://www.nps.gov/maritime/index.htm|title=Maritime Heritage Program &#124; National Park Service|website=www.nps.gov}}</ref>

===Range lights===
{{main|Range lights}}
[[File:Margaree Harbour Range Lights.jpg|right|thumb|Range Lights in [[Margaree Harbour, Nova Scotia]]. When a vessel is on the correct course, the two lights align one above the other.]]
Aligning two fixed points on land provides a navigator with a [[line of position]] called a range in North America and a [[navigational transit|transit]] in Britain. Ranges can be used to precisely align a vessel within a narrow channel such as a river. With landmarks of a range illuminated with a set of fixed lighthouses, nighttime navigation is possible.

Such paired lighthouses are called [[Leading lights|range lights]] in North America and [[leading lights]] in the United Kingdom. The closer light is referred to as the beacon or front range; the further light is called the rear range. The rear range light is almost always taller than the front.

When a vessel is on the correct course, the two lights align vertically, but when the observer is out of position, the difference in alignment indicates the direction of travel to correct the course.

===Location===
[[File:Faro Les Éclaireurs, Ushuaia 11.JPG|thumb|The [[Les Eclaireurs Lighthouse]] in [[Ushuaia]], [[Argentina]].]]
[[File:Kapu Beach Lighthouse .jpg|thumb|[[Kapu, Karnataka|Lighthouse]] located on a higher mound in India<!-- Replace caption with location and name of lighthouse -->]]
[[File:Europa Point Lighthouse.jpg|thumb|Lighthouse at [[Europa Point]], [[Gibraltar]]]]
There are two types of lighthouses: ones that are located on land, and ones that are offshore. <!-- A ''land lighthouse'' is simply a lighthouse constructed to aid navigation over land, rather than water. Historically, they were constructed in areas of flatland where the featureless landscape and prevailing weather conditions (e.g. winter [[fog]]) might cause travelers to become easily disorientated and lost. In such a landscape a high tower with a bright lantern could be visible for many miles.

One example of such a structure is [[Dunston Pillar]], an 18th-century tower built to help travelers crossing the [[heathland]] of mid-[[Lincolnshire]] and to lessen the danger to them from [[highwayman|highwaymen]]. Due to general improvements in transport and navigation throughout the 19th century, land lighthouses became almost totally obsolete as aids to travelers in remote places. In 1940, Dunston Pillar was truncated by 40 feet to preserve low-flying RAF planes.

NOTE: These two paragraphs are unsourced and very misleading. Many, if not most, lighthouses erected to warn watercraft of hazards are built on land. Lighthouses intended to aid navigation on land appear to be very rare. The Dunston Pillar may be unique. -->

''Offshore Lighthouses'' are lighthouses that are not close to land.<ref name="SeaGirt">{{Citation | title     = Lighthouse Terminology Part 2 | work     = Sea Girt Lighthouse | url     = http://www.seagirtlighthouse.com/page/Lighthouse-Terminology-Part-2.aspx | postscript     = . | quote     = A lighthouse located offshore, built on a foundation of pilings, rocks or caissons. | access-date     = 15 February 2013 | archive-date     = 4 April 2013 | archive-url     = https://web.archive.org/web/20130404003030/http://www.seagirtlighthouse.com/page/Lighthouse-Terminology-Part-2.aspx | url-status     = dead }}</ref> There can be a number of reasons for these lighthouses to be built.  There can be a [[shoal]], [[reef]] or submerged [[island]] several miles from land.

The current [[Cordouan Lighthouse]] was completed in 1611, {{convert|7|km|mi}} from the shore on a small islet, but was built on a previous lighthouse that can be traced back to the 880s and is the oldest surviving lighthouse in [[France]]. It is connected to the mainland by a causeway. The oldest surviving oceanic offshore lighthouse is [[Bell Rock Lighthouse]] in the [[North Sea]], off the coast of [[Scotland]].<ref name="Cadbury2012">{{Citation | last1     = Cadbury | first1    = Deborah | title     = Seven Wonders of the Industrial World | edition   = Text only | publisher = HarperCollins UK | page      = 106 | year      = 2012 | isbn      = 978-0007388929 | url       = https://books.google.com/books?id=KHhkY0XVXFwC&pg=PA106 | postscript= .}}</ref>