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69-550: Coverage includes historic and current lighthouse events and an events calendar for lighthouse activities around the United States and elsewhere. They publish a "Doomsday List" (see below) of Endangered lighthouses, and have helped save a number of at-risk lighthouses. They have been credited with uncovering many parts of lighthouse history that had been unknown, or which were thought to have been lost. Each issue carries articles and unusual lighthouse-related stories that, for

138-402: A rescue service , if necessary. Improvements in maritime navigation and safety, such Global Positioning System (GPS), led to the phasing out of non-automated lighthouses across the world. Although several closed due to safety concerns, Canada still maintains 49 staffed lighthouses, split roughly evenly across east and west coasts. The remaining modern lighthouses are usually illuminated by

207-433: A traditional Celtic gesture , buried the head of Geryon with his weapons and ordered that a city be built on the site. The lighthouse, standing atop a skull and crossbones representing the buried head of Hercules' slain enemy, appears in the coat of arms of the city of A Coruña . According to another legend from the 11th-century Irish compilation Lebor Gabála Érenn —the "Book of Invasions"—King Breogán ,

276-640: A Diesel generator for backup. Many Fresnel lens installations have been replaced by rotating aerobeacons , which require less maintenance. In modern automated lighthouses, the system of rotating lenses is often replaced by a high intensity light that emits brief omnidirectional flashes, concentrating the light in time rather than direction. These lights are similar to obstruction lights used to warn aircraft of tall structures. Later innovations were "Vega Lights", and experiments with light-emitting diode (LED) panels. LED lights, which use less energy and are easier to maintain, had come into widespread use by 2020. In

345-604: A Doomsday List of Canadian endangered lighthouses, though according to Russ Rowlett it is not truly national in scope as most of the lighthouses listed are in Nova Scotia . Russ Rowlett keeps a more complete list with no official standing. A similar list for lighthouses in Puerto Rico was constructed by Sandra Shanklin for the Lighthouse Digest in 2002. This hobby magazine or journal-related article

414-510: A figurative sense, the end of the Earth – hence its name, Finisterra . This region is notorious for shipwrecks, earning it the name Costa da Morte , "Coast of Death". Through the millennia, many mythical stories of the lighthouse's origin have been told. According to a myth that mixes Celtic and Greco-Roman elements, the hero Hercules slew the giant tyrant Geryon after three days and three nights of continuous battle. Hercules then, in

483-436: A filament source. Experimental installations of laser lights, either at high power to provide a "line of light" in the sky or, utilising low power, aimed towards mariners have identified problems of increased complexity in installation and maintenance, and high power requirements. The first practical installation, in 1971 at Point Danger lighthouse , Queensland , was replaced by a conventional light after four years, because

552-457: A form of concrete that will set under water used by the Romans, and developed a technique of securing the granite blocks together using dovetail joints and marble dowels . The dovetailing feature served to improve the structural stability , although Smeaton also had to taper the thickness of the tower towards the top, for which he curved the tower inwards on a gentle gradient. This profile had

621-414: A horizontal plane, and horizontally the light is focused into one or a few directions at a time, with the light beam swept around. As a result, in addition to seeing the side of the light beam, the light is directly visible from greater distances, and with an identifying light characteristic . This concentration of light is accomplished with a rotating lens assembly. In early lighthouses, the light source

690-445: A misreading of the ancient inscription. Early geographical descriptions of the location of Brigantia point out that the town could be actually located in A Coruña or the location of the modern town of Betanzos . There is some debate about this, as the people of Betanzos claim it as a fact that Betanzos is "the former city of Brigancia" until the 17th century, both in literary accounts as well as in maps, and they also believe that

759-427: A more powerful hyperradiant Fresnel lens manufactured by the firm of Chance Brothers . 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 fog-signaling building. The Lighthouse itself consists of a tower structure supporting

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828-602: A navigator with a line of position called a range in North America and a 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 range lights in North America and leading lights in the United Kingdom. The closer light

897-521: A number of screw-pile lighthouses. Englishman James Douglass was knighted for his work on the fourth Eddystone Lighthouse. United States Army Corps of Engineers Lieutenant George Meade built numerous lighthouses along the Atlantic and Gulf coasts before gaining wider fame as the winning general at the Battle of Gettysburg . Colonel Orlando M. Poe , engineer to General William Tecumseh Sherman in

966-402: A particular color (usually formed by colored panes in the lantern) to distinguish safe water areas from dangerous shoals. Modern lighthouses often have unique reflectors or racon transponders so the radar signature of the light is also unique. Before modern strobe lights , lenses were used to concentrate the light from a continuous source. Vertical light rays of the lamp are redirected into

1035-411: A reservoir mounted above the burner. The lamp was first produced by Matthew Boulton , in partnership with Argand, in 1784, and became the standard for lighthouses for over a century. South Foreland Lighthouse was the first tower to successfully use an electric light in 1875. The lighthouse's carbon arc lamps were powered by a steam-driven magneto . John Richardson Wigham was the first to develop

1104-415: A single stationary flashing light powered by solar-charged batteries and mounted on a steel skeleton tower. Where the power requirement is too great for solar power alone, cycle charging of the battery by a Diesel generator is provided. The generator only comes into use when the battery needs charging, saving fuel and increasing periods between maintenance. John Smeaton is noteworthy for having designed

1173-477: A system for gas illumination of lighthouses. His improved gas 'crocus' burner at the Baily Lighthouse near Dublin was 13 times more powerful than the most brilliant light then known. The vaporized oil burner was invented in 1901 by Arthur Kitson , and improved by David Hood at Trinity House . The fuel was vaporized at high pressure and burned to heat the mantle, giving an output of over six times

1242-457: Is a stub . You can help Misplaced Pages by expanding it . See tips for writing articles about magazines . Further suggestions might be found on the article's talk page . This lighthouse -related article is a stub . You can help Misplaced Pages by expanding it . This article about a history-focused magazine is a stub . You can help Misplaced Pages by expanding it . See tips for writing articles about magazines . Further suggestions might be found on

1311-534: Is believed to come from the Proto-Celtic root *klou̯ni (cf. Old Irish cluain ), meaning meadow . However, the A Coruña tradition maintains that the "port" of Betanzos (which is a fluvial one in a quite small river) was far too small for Roman warships to dock at; Julius Caesar , for example, is said to have visited this area with "more than a hundred triremes ". A Coruña was an important Roman site, as graveyards and other Roman remains have been found in

1380-471: Is known to have existed by the 1st century. It was built (or perhaps rebuilt) under Trajan , possibly on foundations following a design that was Phoenician in origin. The design was based on the original plans of the Lighthouse of Alexandria . Its base preserves a cornerstone with the inscription MARTI AVG.SACR C.SEVIVS LVPVS ARCHITECTVS ÆMINIENSIS LVSITANVS.EX.VO , ascribing the tower's design to

1449-419: Is one example. Race Rocks Light in western Canada is painted in horizontal black and white bands to stand out against the horizon. 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 Distance to the horizon ) as D = 1.22 H {\displaystyle D=1.22{\sqrt {H}}} , where H

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1518-572: 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. There are two types of lighthouses: ones that are located on land, and ones that are offshore. Tower of Hercules The Tower of Hercules ( Galician : Torre de Hércules , Spanish : Torre de Hércules )

1587-510: Is the height above water in feet, and D is the distance from the lighthouse to the horizon in nautical miles, the lighthouse range . 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

1656-558: Is the oldest known extant Roman lighthouse . Built in the 1st century , the tower is located on a peninsula about 2.4 km (1.5 mi) from the center of A Coruña , Galicia, in northwestern Spain. Until the 20th century, it was known as the Farum Brigantium . The Latin word farum is derived from the Greek Φάρος , Pharos , for the Lighthouse of Alexandria . The structure stands 55 metres (180 ft) tall and overlooks

1725-622: The Florida Reef along the Florida Keys, beginning with the Carysfort Reef Light in 1852. In waters too deep for a conventional structure, a lightship might be used instead of a lighthouse, such as the former 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 . Aligning two fixed points on land provides

1794-644: The United States and Canada , but occasionally includes sites from other countries as well. Inclusion on the list raises awareness that a lighthouse is in trouble. The list is updated bi-yearly. Russ Rowlett keeps an annotated version of the Doomsday List on the Lighthouse Directory. He has also compiled a Watch List of other lighthouses he feels should be on the Doomsday List. The Nova Scotia Lighthouse Preservation Society also holds

1863-513: 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

1932-588: The North Atlantic coast of Spain. The tower was renovated in 1791. There is a sculpture garden on the grounds of the lighthouse featuring works by Pablo Serrano and Francisco Leiro  [ es ] . The Tower of Hercules is a National Monument of Spain and has been a UNESCO World Heritage Site since 27 June 2009. It is the second-tallest lighthouse in Spain, after the Faro de Chipiona . The tower

2001-466: The Swiss scientist Aimé Argand revolutionized lighthouse illumination with its steady smokeless flame. Early models used ground glass which was sometimes tinted around the wick. Later models used a mantle of thorium dioxide suspended over the flame, creating a bright, steady light. The Argand lamp used whale oil , colza , olive oil or other vegetable oil as fuel, supplied by a gravity feed from

2070-803: The Tower. Throughout the Middle Ages, multiple naval crusading itineraries to the Holy Land mentioned the obligatory stopover at the Lighthouse. Usually, the crusader fleets would disembark there to reach the shrine of the Apostle James the Greater at Santiago de Compostela on foot. De expugnatione Lyxbonensi and De itinere Frisunum helped to perpetuate the legend that the lighthouse had been built by Julius Caesar perhaps due to

2139-405: The United Kingdom and Ireland about a third of lighthouses had been converted from filament light sources to use LEDs, and conversion continued with about three per year. The light sources are designed to replicate the colour and character of the traditional light as closely as possible. The change is often not noticed by people in the region, but sometimes a proposed change leads to calls to preserve

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2208-495: The added advantage of allowing some of the energy of the waves to dissipate on impact with the walls. His lighthouse was the prototype for the modern lighthouse and influenced all subsequent engineers. One such influence was Robert Stevenson , himself a seminal figure in the development of lighthouse design and construction. His greatest achievement was the construction of the Bell Rock Lighthouse in 1810, one of

2277-490: The architect Gaius Sevius Lupus, from Aeminium (present-day Coimbra , Portugal) in the former province of Lusitania , as an offering to the Roman god of war, Mars . The tower has been in consistent use since the 2nd century. The original tower was shorter and wider than the current tower, as the surviving core was surrounded by a spiral ramp. The outline of this ramp is still visible in the restored exterior. The final storey of

2346-448: The article's talk page . 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 mark dangerous coastlines, hazardous shoals , reefs , rocks, and safe entries to harbors; they also assist in aerial navigation . Once widely used,

2415-491: The beam was too narrow to be seen easily. In any of these designs an observer, rather than seeing a continuous weak light, sees a brighter light during short time intervals. These instants of bright light are arranged to create a light characteristic or pattern specific to a lighthouse. For example, the Scheveningen Lighthouse flashes are alternately 2.5 and 7.5 seconds. Some lights have sectors of

2484-406: The choice of light sources, mountings, reflector design, the use of Fresnel lenses , and in rotation and shuttering systems providing lighthouses with individual signatures allowing them to be identified by seafarers. He also invented the movable jib and the balance-crane as a necessary part for lighthouse construction. Alexander Mitchell designed the first screw-pile lighthouse – his lighthouse

2553-407: The city centre, demonstrating that the site was inhabited in the Roman period and was deserted only during the early Middle Ages due to Viking attacks , when its people moved inland to O Burgo (now Culleredo ). The proponents of A Coruña as Brigantia also explain the different name as a change that occurred in the Middle Ages and point out that the lighthouse, which was called "Pharum Brigantium",

2622-533: The collapse of the Soviet government in 1990s, most of the official records on the locations, and condition, of these lighthouses were reportedly lost. Over time, the condition of RTGs in Russia degraded; many of them fell victim to vandalism and scrap metal thieves, who may not have been aware of the dangerous radioactive contents. Energy-efficient LED lights can be powered by solar panels , with batteries instead of

2691-488: The construction of lenses of large aperture and short focal length , without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. A Fresnel lens can also capture more oblique light from a light source, thus allowing the light from a lighthouse equipped with one to be visible over greater distances. The first Fresnel lens

2760-625: The development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for reefs and promontories , unlike many modern lighthouses. The most famous lighthouse structure from antiquity was the Pharos of Alexandria , Egypt , which collapsed following a series of earthquakes between 956 and 1323. The intact Tower of Hercules at A Coruña , Spain gives insight into ancient lighthouse construction; other evidence about lighthouses exists in depictions on coins and mosaics, of which many represent

2829-473: The emitted light into a concentrated beam, thereby greatly increasing the light's visibility. The ability to focus the light led to the first revolving lighthouse beams, where the light would appear to the mariners as a series of intermittent flashes. It also became possible to transmit complex signals using the light flashes. French physicist and engineer Augustin-Jean Fresnel developed the multi-part Fresnel lens for use in lighthouses. His design allowed for

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2898-412: 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 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

2967-585: The founding father of the Galician Celtic nation , constructed a massive tower of such a grand height that his sons could see a distant green shore from its top. The glimpse of that distant green land lured them to sail north to Ireland. According to the legend, Breogán's descendants stayed in Ireland and are the Celtic ancestors of the current Irish people. A colossal statue of Breogán has been erected near

3036-455: 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 muntins (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

3105-535: The light is concentrated, if needed, by the "lens" or "optic". Power sources for lighthouses in the 20th–21st centuries vary. Originally lit by open fires and later candles, the Argand hollow wick lamp and parabolic reflector were introduced in the late 18th century. Whale oil was also used with wicks as the source of light. Kerosene became popular in the 1870s and electricity and acetylene gas derived on-site from calcium carbide began replacing kerosene around

3174-509: The lighthouse at Ostia . Coins from Alexandria, Ostia, and Laodicea in Syria also exist. The modern era of lighthouses began at the turn of the 18th century, as the number of lighthouses being constructed increased significantly due to much higher levels of transatlantic commerce. Advances in structural engineering and new and efficient lighting equipment allowed for the creation of larger and more powerful lighthouses, including ones exposed to

3243-469: The lighthouse keepers. Efficiently concentrating the light from a large omnidirectional light source requires a very large diameter lens. This would require a very thick and heavy lens if a conventional lens were used. The Fresnel lens (pronounced / f r eɪ ˈ n ɛ l / ) focused 85% of a lamp's light versus the 20% focused with the parabolic reflectors of the time. Its design enabled construction of lenses of large size and short focal length without

3312-470: The luminosity of traditional oil lights. The use of gas as illuminant became widely available with the invention of the Dalén light by Swedish engineer Gustaf Dalén . He used Agamassan (Aga), a substrate , to absorb the gas, allowing the gas to be stored, and hence used, safely. Dalén also invented the ' sun valve ', which automatically regulated the light and turned it off during the daytime. The technology

3381-421: 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

3450-496: The most impressive feats of engineering of the age. This structure was based upon Smeaton's design, but with several improved features, such as the incorporation of rotating lights, alternating between red and white. Stevenson worked for the Northern Lighthouse Board for nearly fifty years during which time he designed and oversaw the construction and later improvement of numerous lighthouses. He innovated in

3519-542: The most part, cannot be found elsewhere, and many photos, historic and contemporary. Tim Harrison died on August 19, 2023, at the age of 75. Lighthouse Digest has subscribers in all 50 United States and 17 other nations. Currently it publishes six issues a year. The editor was Tim Harrison; the Managing editor is Kathleen Finnegan-Harrison. The Doomsday List is a list of endangered lighthouses compiled by Lighthouse Digest . The list usually consists of lighthouses in

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3588-484: The name Betanzos is a phonetical evolution from Brigantium > Breganzo > Betanzos . This could, however, be a false etymology . The Betanzos tradition claims that the port of Betanzos was getting too small for the larger medieval ships and that king Alfonso IX of León decided to create a bigger port nearby in the 13th century. The place he chose was an uninhabited place called Clunia , which later on evolved to Cruña and eventually Coruña . The place name Clunia

3657-402: The number of operational lighthouses has declined due to the expense of maintenance and the advent of much cheaper, more sophisticated, and more effective electronic navigational systems. Before the development of clearly defined ports , mariners were guided by fires built on hilltops. Since elevating the fire would improve visibility, placing the fire on a platform became a practice that led to

3726-419: The reign of Charles III of Spain , and was finished in 1791. UNESCO praised the work: "The Tower of Hercules was restored in the 18th century in an exemplary manner, which has protected the central core of the original Roman monument while restoring its technical functions". Within, the much-repaired Roman and medieval masonry remains visible. The Romans who conquered this region of Spain believed it to be, in

3795-465: The sea. The function of lighthouses was gradually changed from indicating ports to the providing of a visible warning against shipping hazards, such as rocks or reefs. The Eddystone Rocks were a major shipwreck hazard for mariners sailing through the English Channel . The first lighthouse built there was an octagonal wooden structure, anchored by 12 iron stanchions secured in the rock, and

3864-451: 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. Skeletal iron towers with screw-pile foundations were built on

3933-554: The siege of Atlanta, designed and built some of the most exotic lighthouses in the most difficult locations on the U.S. Great Lakes . French merchant navy officer Marius Michel Pasha built almost a hundred lighthouses along the coasts of the Ottoman Empire in a period of twenty years after the Crimean War (1853–1856). In a lighthouse, the source of light is called the "lamp" (whether electric or fuelled by oil) and

4002-528: 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 . As technology advanced, prefabricated skeletal iron or steel structures tended to be used for lighthouses constructed in

4071-599: The third and most famous Eddystone Lighthouse , but some builders are well known for their work in building multiple lighthouses. The Stevenson family ( Robert , Alan , David , Thomas , David Alan , and Charles ) made lighthouse building a three-generation profession in Scotland. Richard Henry Brunton designed and built 26 Japanese lighthouses in Meiji Era Japan, which became known as Brunton's "children". Blind Irishman Alexander Mitchell invented and built

4140-467: The tower was likely topped with a dome. The earliest known reference to the lighthouse at Brigantium is by Paulus Orosius in Historiae adversum Paganos , written around 415–417: In 1788, the surviving 34-metre (112 ft) tower core was given a neoclassical restoration, including a new 21-metre (69 ft) fourth storey. The restoration was undertaken by naval engineer Eustaquio Giannini during

4209-486: The traditional light, including in some cases a rotating beam. A typical LED system designed to fit into the traditional 19th century Fresnel lens enclosure was developed by Trinity House and two other lighthouse authorities and costs about € 20,000, depending on configuration, according to a supplier; it has large fins to dissipate heat. Lifetime of the LED light source is 50,000 to 100,000 hours, compared to about 1,000 hours for

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4278-480: The turn of the 20th century. Carbide was promoted by the Dalén light , which automatically lit the lamp at nightfall and extinguished it at dawn. In the second half of the 20th century, many remote lighthouses in Russia (then Soviet Union ) were powered by radioisotope thermoelectric generators (RTGs). These had the advantage of providing power day or night and did not need refuelling or maintenance. However, after

4347-535: 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. 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

4416-643: The weight and volume of material in conventional lens designs. Fresnel lighthouse lenses are ranked by order , a measure of refracting power, with a first order lens being the largest, most powerful and expensive; and a sixth order lens being the smallest. The order is based on the focal length of the lens. A first order lens has the longest focal length, with the sixth being the shortest. Coastal lighthouses generally use first, second, or third order lenses, while harbor lights and beacons use fourth, fifth, or sixth order lenses. Some lighthouses, such as those at Cape Race , Newfoundland, and Makapuu Point , Hawaii, used

4485-437: Was a kerosene lamp or, earlier, an animal or vegetable oil Argand lamp, and the lenses rotated by a weight driven clockwork assembly wound by lighthouse keepers, sometimes as often as every two hours. The lens assembly sometimes floated in liquid mercury to reduce friction. In more modern lighthouses, electric lights and motor drives were used, generally powered by diesel electric generators. These also supplied electricity for

4554-459: Was built by Henry Winstanley from 1696 to 1698. His lighthouse was the first tower in the world to have been fully exposed to the open sea. The civil engineer John Smeaton rebuilt the lighthouse from 1756 to 1759; his tower marked a major step forward in the design of lighthouses and remained in use until 1877. He modeled the shape of his lighthouse on that of an oak tree , using granite blocks. He rediscovered and used " hydraulic lime ",

4623-683: Was built on piles that were screwed into the sandy or muddy seabed. Construction of his design began in 1838 at the mouth of the Thames and was known as the Maplin Sands lighthouse, and first lit in 1841. Although its construction began later, the Wyre Light in Fleetwood, Lancashire, was the first to be lit (in 1840). Until 1782 the source of illumination had generally been wood pyres or burning coal. The Argand lamp , invented in 1782 by

4692-506: Was the predominant light source in lighthouses from the 1900s to the 1960s, when electric lighting had become dominant. With the development of the steady illumination of the Argand lamp, the application of optical lenses to increase and focus the light intensity became a practical possibility. William Hutchinson developed the first practical optical system in 1777, known as a catoptric system. This rudimentary system effectively collimated

4761-598: Was used in 1823 in the Cordouan lighthouse at the mouth of the Gironde estuary ; its light could be seen from more than 20 miles (32 km) out. Fresnel's invention increased the luminosity of the lighthouse lamp by a factor of four and his system is still in common use. The introduction of electrification and automatic lamp changers began to make lighthouse keepers obsolete. For many years, lighthouses still had keepers, partly because lighthouse keepers could serve as

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