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110-588: The Rock Harbor Lighthouse is a light station located in Rock Harbor on Isle Royale National Park , Michigan . It was listed on the National Register of Historic Places in 1977. The Rock Harbor Lighthouse is a 50-foot-tall (15 m) cylindrical tower with a 16-foot-diameter (4.9 m) base, constructed of randomly placed stone and brick, capped with an octagonal beacon with a copper roof. A one-and-a-half-story keeper's house with gabled roof

220-402: 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

330-543: A 25 kilometres (16 mi) stretch of light steel netting called the Dover Barrage , which it was hoped would ensnare submerged submarines. After initial success, the Germans learned how to pass through the barrage, aided by the unreliability of British mines. On 31 January 1917, the Germans resumed unrestricted submarine warfare leading to dire Admiralty predictions that submarines would defeat Britain by November,

440-640: 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 Many Fresnel lens installations have been replaced by rotating aerobeacons , which require less maintenance.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

550-436: 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

660-457: 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

770-414: 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

880-427: 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

990-602: 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

1100-521: 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

1210-402: 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

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1320-513: A protected World Heritage Site coastline. The ship had been damaged and was en route to Portland Harbour . The English Channel, despite being a busy shipping lane, remains in part a haven for wildlife. Atlantic oceanic species are more common in the westernmost parts of the channel, particularly to the west of Start Point, Devon , but can sometimes be found further east towards Dorset and the Isle of Wight. Seal sightings are becoming more common along

1430-411: 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

1540-415: 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

1650-477: 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

1760-472: Is connected to the tower on one end. In 1852, due to the increase in shipping in Lake Superior , it was recommended that a new light be constructed on Isle Royale ; the next year, Congress appropriated $ 5,000 to construct a light at Rock Harbor. Construction began in 1855, and was completed in 1856. The Rock Island Light was the first lighthouse constructed on Isle Royale . The first keeper arrived at

1870-419: 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

1980-518: 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. English Channel The English Channel , also known as

2090-510: 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

2200-408: The Battle of Britain featured German air attacks on Channel shipping and ports; despite these early successes against shipping the Germans did not win the air supremacy necessary for Operation Sealion , the projected cross-Channel invasion. The Channel subsequently became the stage for an intensive coastal war, featuring submarines, minesweepers , and Fast Attack Craft . The narrow waters of

2310-622: 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

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2420-661: The Glorious Revolution of 1688, while the concentration of excellent harbours in the Western Channel on Britain's south coast made possible the largest amphibious invasion in history, the Normandy Landings in 1944. Channel naval battles include the Battle of the Downs (1639), Battle of Dover (1652), the Battle of Portland (1653) and the Battle of La Hougue (1692). In more peaceful times,

2530-708: The Low Countries . The North Sea reaches much greater depths east of northern Britain. The Channel descends briefly to 180 m (590 ft) in the submerged valley of Hurd's Deep , 48 km (30 mi) west-northwest of Guernsey . There are several major islands in the Channel, the most notable being the Isle of Wight off the English coast, and the Channel Islands , British Crown Dependencies off

2640-586: The Neolithic front in southern Europe to the Mesolithic peoples of northern Europe." The Ferriby Boats , Hanson Log Boats and the later Dover Bronze Age Boat could carry a substantial cross-Channel cargo. Diodorus Siculus and Pliny both suggest trade between the rebel Celtic tribes of Armorica and Iron Age Britain flourished. In 55 BC Julius Caesar invaded, claiming that the Britons had aided

2750-494: The Norman Conquest beginning with the Battle of Hastings , while retaining the fiefdom of Normandy for himself and his descendants. In 1204, during the reign of King John , mainland Normandy was taken from England by France under Philip II , while insular Normandy (the Channel Islands ) remained under English control. In 1259, Henry III of England recognised the legality of French possession of mainland Normandy under

2860-840: The North Sea to the Western Atlantic via the Strait of Dover is of geologically recent origin, having formed late in the Pleistocene period. The English Channel first developed as an arm of the Atlantic Ocean during the Pliocene period (5.3-2.6 million years ago) as a result of differential tectonic uplift along pre-existing tectonic weaknesses during the Oligocene and Miocene periods. During this early period,

2970-628: The Strait of Dover . It is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some 75,000 square kilometres (22,000 square nautical miles; 29,000 square miles). The Channel aided the United Kingdom in becoming a naval superpower, serving as a natural defence to halt attempted invasions, such as in the Napoleonic Wars and in the Second World War . The northern, English coast of

3080-760: The Treaty of Paris . His successors, however, often fought to regain control of mainland Normandy. With the rise of William the Conqueror , the North Sea and Channel began to lose some of their importance. The new order oriented most of England and Scandinavia's trade south, toward the Mediterranean and the Orient. Although the British surrendered claims to mainland Normandy and other French possessions in 1801,

3190-491: The Treaty of Paris of 1259 , the surrender of French possessions in 1801, and the belief that the rights of succession to that title are subject to Salic Law which excludes inheritance through female heirs. French Normandy was occupied by English forces during the Hundred Years' War in 1346–1360 and again in 1415–1450. From the reign of Elizabeth I , English foreign policy concentrated on preventing invasion across

3300-597: The Veneti against him the previous year. He was more successful in 54 BC , but Britain was not fully established as part of the Roman Empire until Aulus Plautius 's 43 AD invasion . A brisk and regular trade began between ports in Roman Gaul and those in Britain. This traffic continued until the end of Roman rule in Britain in 410 AD, after which the early Anglo-Saxons left less clear historical records. In

3410-630: The Ärmelkanal in German, or a direct borrowing , such as Canal de la Mancha in Spanish. The International Hydrographic Organization defines the limits of the English Channel as: The Strait of Dover (French: Pas de Calais ), at the Channel's eastern end, is its narrowest point, while its widest point lies between Lyme Bay and the Gulf of Saint Malo , near its midpoint. Well on

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3520-513: 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

3630-409: The Atlantic. The flooding destroyed the ridge that connected Britain to continental Europe , although a land connection across the southern North Sea would have existed intermittently at later times when periods of glaciation resulted in lowering of sea levels. During interglacial periods (when sea levels were high) between the initial flooding 450,000 years ago until around 180,000 years ago,

3740-529: The Channel , is an arm of the Atlantic Ocean that separates Southern England from northern France . It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busiest shipping area in the world. It is about 560 kilometres (300 nautical miles; 350 statute miles) long and varies in width from 240 km (130 nmi; 150 mi) at its widest to 34 km (18 nmi; 21 mi) at its narrowest in

3850-535: The Channel by ensuring no major European power controlled the potential Dutch and Flemish invasion ports. Her climb to the pre-eminent sea power of the world began in 1588 as the attempted invasion of the Spanish Armada was defeated by the combination of outstanding naval tactics by the English and the Dutch under command of Charles Howard, 1st Earl of Nottingham with Sir Francis Drake second in command, and

3960-532: The Channel did not connect to the North Sea, with Britain and Ireland remaining part of continental Europe , linked by an unbroken Weald–Artois anticline , a ridge running between the Dover and Calais regions. During Pleistocene glacial periods this ridge acted as a natural dam holding back a large freshwater pro-glacial lake in the Doggerland region, now submerged under the North Sea . During this period,

4070-455: The Channel for several weeks, but was thwarted following the British naval victory at the Battle of Quiberon Bay in 1759 and was unsuccessful (The last French landing on English soil being in 1690 with a raid on Teignmouth, although the last French raid on British soil was a raid on Fishguard, Wales in 1797). Another significant challenge to British domination of the seas came during the Napoleonic Wars . The Battle of Trafalgar took place off

4180-511: The Channel is more populous than the southern, French coast. The major languages spoken in this region are English and French . Roman sources as Oceanus Britannicus (or Mare Britannicum , meaning the Ocean, or the Sea, of the Britons or Britannī ). Variations of this term were used by influential writers such as Ptolemy , and remained popular with British and continental authors well into

4290-723: The Channel served as a link joining shared cultures and political structures, particularly the huge Angevin Empire from 1135 to 1217. For nearly a thousand years, the Channel also provided a link between the Modern Celtic regions and languages of Cornwall and Brittany . Brittany was founded by Britons who fled Cornwall and Devon after Anglo-Saxon encroachment. In Brittany, there is a region known as " Cornouaille " (Cornwall) in French and "Kernev" in Breton . In ancient times there

4400-598: The Channel would still have been separated from the North Sea by a landbridge to the north of the Strait of Dover (the Strait of Dover at this time formed part of a estuary fed by the Thames and Scheldt ), restricting interchange of marine fauna between the Channel and the North Sea (except perhaps by occasional overtopping). During the Last Interglacial/Eemian (115–130,000 years ago) the connection between

4510-608: The English Channel, with both Grey Seal and Harbour Seal recorded frequently. The Channel is thought to have prevented Neanderthals from colonising Britain during the Last Interglacial/Eemian, though they returned to Britain during the Last Glacial Period when sea levels were lower. The Channel has in historic times been both an easy entry for seafaring people and a key natural defence, halting invading armies while in conjunction with control of

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4620-474: The Isle of Wight and the mainland. The Celtic Sea is to the west of the Channel. The Channel acts as a funnel that amplifies the tidal range from less than a metre at sea in eastern places to more than 6 metres in the Channel Islands , the west coast of the Cotentin Peninsula and the north coast of Brittany in monthly spring tides . The time difference of about six hours between high water at

4730-451: The North Sea allowing Britain to blockade the continent. The most significant failed invasion threats came when the Dutch and Belgian ports were held by a major continental power, e.g. from the Spanish Armada in 1588, Napoleon during the Napoleonic Wars , and Nazi Germany during World War II . Successful invasions include the Roman conquest of Britain , the Norman Conquest in 1066 and

4840-579: The North Sea and almost all of the British Isles were covered by ice. The lake was fed by meltwater from the Baltic and from the Caledonian and Scandinavian ice sheets that joined to the north, blocking its exit. The sea level was about 120 m (390 ft) lower than it is today. Then, between 450,000 and 180,000 years ago, at least two catastrophic glacial lake outburst floods breached

4950-543: The North Sea and the English Channel was fully open as it is today, resulting in Britain being an island during this interval, before lowered sea levels reconnected it to the continent during the Last Glacial Period . From the end of the Last Glacial Period, to the beginning of the Holocene rising sea levels again resulted in the unimpeded connection between the North Sea and the English Channel resuming due to

5060-466: 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

5170-405: 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

5280-539: The Weald–Artois anticline. These contributed to creating some of the deepest parts of the channel such as Hurd's Deep . The first flood of 450,000 years ago would have lasted for several months, releasing as much as one million cubic metres of water per second. The flood started with large but localised waterfalls over the ridge, which excavated depressions now known as the Fosses Dangeard . The flow eroded

5390-495: 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

5500-499: The arrival of the Romans in the area. The modern Welsh is often given as Môr Udd (the Lord's or Prince's Sea); however, this name originally described both the Channel and the North Sea combined. Anglo-Saxon texts make reference to the sea as Sūð-sǣ (South Sea), but this term fell out of favour, as later English authors followed the same conventions as their Latin and Norman contemporaries. One English name that did persist

5610-491: 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

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5720-686: The beginning of the Viking Age . For the next 250 years the Scandinavian raiders of Norway, Sweden, and Denmark dominated the North Sea, raiding monasteries, homes, and towns along the coast and along the rivers that ran inland. According to the Anglo-Saxon Chronicle they began to settle in Britain in 851. They continued to settle in the British Isles and the continent until around 1050, with some raids recorded along

5830-517: The centre of the Straits of Dover and into the English Channel. It left streamlined islands, longitudinal erosional grooves, and other features characteristic of catastrophic megaflood events, still present on the sea floor and now revealed by high-resolution sonar. Through the scoured channel passed a river, the Channel River , which drained the combined Rhine and Thames westwards to

5940-666: The channel coast of England, including at Wareham, Portland, near Weymouth and along the river Teign in Devon. The fiefdom of Normandy was created for the Viking leader Rollo (also known as Robert of Normandy). Rollo had besieged Paris but in 911 entered vassalage to the king of the West Franks Charles the Simple through the Treaty of St.-Claire-sur-Epte . In exchange for his homage and fealty , Rollo legally gained

6050-406: 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

6160-568: The coast of France. The coastline, particularly on the French shore, is deeply indented, with several small islands close to the coastline, including Chausey and Mont-Saint-Michel . The Cotentin Peninsula on the French coast juts out into the Channel, with the wide Bay of the Seine (French: Baie de Seine ) to its east. On the English side there is a small parallel strait , the Solent , between

6270-492: The coast of Spain against a combined French and Spanish fleet and was won by Admiral Horatio Nelson , ending Napoleon 's plans for a cross-Channel invasion and securing British dominance of the seas for over a century. The exceptional strategic importance of the Channel as a tool for blockading was recognised by the First Sea Lord Admiral Fisher in the years before World War I . "Five keys lock up

6380-533: 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

6490-488: 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

6600-551: The continental shelf, it has an average depth of about 120 m (390 ft) at its widest; yet averages about 45 m (148 ft) between Dover and Calais , its notable sandbank hazard being Goodwin Sands . Eastwards from there the adjoining North Sea reduces to about 26 m (85 ft) across the Broad Fourteens (14 fathoms) where it lies over the southern cusp of the former land bridge between East Anglia and

6710-404: The description suggests the name had recently been adopted. In the sixteenth century, Dutch maps referred to the sea as the Engelse Kanaal (English Channel) and by the 1590s, William Shakespeare used the word Channel in his history plays of Henry VI , suggesting that by that time, the name was popularly understood by English people. By the eighteenth century, the name English Channel

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6820-573: 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

6930-434: The eastern and western limits of the Channel is indicative of the tidal range being amplified further by resonance . Amphidromic points are the Bay of Biscay and varying more in precise location in the far south of the North Sea, meaning both those associated eastern coasts repel the tides effectively, leaving the Strait of Dover as every six hours the natural bottleneck short of its consequent gravity-induced repulsion of

7040-473: 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

7150-414: The end of the war and the project was abandoned. The naval blockade in the Channel and North Sea was one of the decisive factors in the German defeat in 1918. During the Second World War , naval activity in the European theatre was primarily limited to the Atlantic . During the Battle of France in May 1940, the German forces succeeded in capturing both Boulogne and Calais , thereby threatening

7260-412: 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

7370-454: The following stormy weather. Over the centuries the Royal Navy slowly grew to be the most powerful in the world. The building of the British Empire was possible only because the Royal Navy eventually managed to exercise unquestioned control over the seas around Europe, especially the Channel and the North Sea. During the Seven Years' War , France attempted to launch an invasion of Britain . To achieve this France needed to gain control of

7480-402: The frontier of Switzerland to the English Channel", they reached the coast at the North Sea. Much of the British war effort in Flanders was a bloody but successful strategy to prevent the Germans reaching the Channel coast. At the outset of the war, an attempt was made to block the path of U-boats through the Dover Strait with naval minefields . By February 1915, this had been augmented by

7590-540: The keeper's house was altered, including the addition of dormers. In the 1950s, the tower began to tilt, and an emergency stabilization was undertaken; the tower still leans approximately 2 degrees. The original wooden roof of the structure was replaced with asphalt in 1962, and the foundation was stabilized in 1969. The station is currently unmanned. Lighthouse Lighthouses mark dangerous coastlines, hazardous shoals , reefs , rocks, and safe entries to harbors; they also assist in aerial navigation . Once widely used,

7700-455: 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

7810-483: 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

7920-509: 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

8030-469: 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

8140-686: The line of retreat for the British Expeditionary Force . By a combination of hard fighting and German indecision, the port of Dunkirk was kept open allowing 338,000 Allied troops to be evacuated in Operation Dynamo . More than 11,000 were evacuated from Le Havre during Operation Cycle and a further 192,000 were evacuated from ports further down the coast in Operation Aerial in June 1940. The early stages of

8250-470: 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

8360-421: 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

8470-532: The modern era. Other Latin names for the sea include Oceanus Gallicus (the Gaulish Ocean) which was used by Isidore of Seville in the sixth century. The term British Sea is still used by speakers of Cornish and Breton , with the sea known to them as Mor Bretannek and Mor Breizh respectively. While it is likely that these names derive from the Latin term, it is possible that they predate

8580-659: The monarch of the United Kingdom retains the title Duke of Normandy in respect to the Channel Islands. The Channel Islands (except for Chausey ) are Crown Dependencies of the British Crown . Thus the Loyal toast in the Channel Islands is Le roi, notre Duc ("The King, our Duke"). The British monarch is understood to not be the Duke of Normandy in regards of the French region of Normandy described herein, by virtue of

8690-703: The most dangerous situation Britain faced in either world war. The Battle of Passchendaele in 1917 was fought to reduce the threat by capturing the submarine bases on the Belgian coast, though it was the introduction of convoys and not capture of the bases that averted defeat. In April 1918 the Dover Patrol carried out the Zeebrugge Raid against the U-boat bases. During 1917, the Dover Barrage

8800-496: 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

8910-402: 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

9020-540: The power vacuum left by the retreating Romans, the Germanic Angles , Saxons , and Jutes began the next great migration across the North Sea. Having already been used as mercenaries in Britain by the Romans, many people from these tribes crossed during the Migration Period , conquering and perhaps displacing the native Celtic populations. The attack on Lindisfarne in 793 is generally considered

9130-541: The retaining ridge, causing the rock dam to fail and releasing lake water into the Atlantic. After multiple episodes of changing sea level, during which the Fosses Dangeard were largely infilled by various layers of sediment, another catastrophic flood some 180,000 years ago carved a large bedrock-floored valley, the Lobourg Channel , some 500 m wide and 25 m deep, from the southern North Sea basin through

9240-465: 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

9350-451: 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

9460-554: 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

9570-606: The sinking of Doggerland , with Britain again becoming an island. As a busy shipping lane, the Channel experiences environmental problems following accidents involving ships with toxic cargo and oil spills. Indeed, over 40% of the UK incidents threatening pollution occur in or very near the Channel. One occurrence was the MSC Napoli , which on 18 January 2007 was beached with nearly 1700 tonnes of dangerous cargo in Lyme Bay,

9680-620: The sleeve (French: la manche ) shape of the Channel. Folk etymology has derived it from a Celtic word meaning 'channel' that is also the source of the name for the Minch in Scotland, but this name is not attested before the 17th century, and French and British sources of that time are clear about its etymology. The name in French has been directly adapted in other languages as either a calque , such as Canale della Manica in Italian or

9790-620: The southward tide (surge) of the North Sea (equally from the Atlantic). The Channel does not experience, but its existence is necessary to explain the extent of North Sea storm surges , such as necessitate the Thames Barrier , Delta Works , Zuiderzee works ( Afsluitdijk and other dams). In the UK Shipping Forecast the Channel is divided into the following areas, from the east: The full English Channel connecting

9900-482: The station on October 24, 1856, and the lighthouse went into operation a short time later. The light had been manned for less than three years when it was determined that, due to the decrease in mining traffic, it was no longer required. It was extinguished on August 1, 1859, and the lighthouse was abandoned. During the American Civil War , copper mining increased once more, and in 1873 renovations began on

10010-629: The station, leading to the reactivation of the light on August 5, 1874. However, after another drop in copper prices, and following the activation in 1875 of the Isle Royale Light at Menagerie Island, the Rock Harbor Light was rendered less useful. On October 4, 1879, the Rock Harbor lighthouse was deactivated for the second and last time, having been in service for a total of only eight years since its construction. In 1910,

10120-528: 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

10230-570: The territory he and his Viking allies had previously conquered. The name "Normandy" reflects Rollo's Viking (i.e. "Northman") origins. The descendants of Rollo and his followers adopted the local Gallo-Romance language and intermarried with the area's inhabitants and became the Normans – a Norman French -speaking mixture of Scandinavians , Hiberno-Norse , Orcadians , Anglo-Danish , and indigenous Franks and Gauls . Rollo's descendant William, Duke of Normandy became king of England in 1066 in

10340-543: 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

10450-486: 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

10560-480: 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

10670-535: 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

10780-643: 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

10890-635: The world! Singapore, the Cape, Alexandria , Gibraltar, Dover." However, on 25 July 1909 Louis Blériot made the first Channel crossing from Calais to Dover in an aeroplane. Blériot's crossing signalled a change in the function of the Channel as a barrier-moat for England against foreign enemies. Because the Kaiserliche Marine surface fleet could not match the British Grand Fleet, the Germans developed submarine warfare , which

11000-437: 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

11110-459: Was also a " Domnonia " (Devon) in Brittany as well. In February 1684 , ice formed on the sea in a belt 4.8 km (3.0 mi) wide off the coast of Kent and 3.2 km (2.0 mi) wide on the French side. Remnants of a mesolithic boatyard have been found on the Isle of Wight . Wheat was traded across the Channel about 8,000 years ago. "... Sophisticated social networks linked

11220-459: 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 ",

11330-683: 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

11440-549: Was first recorded in Middle English in the 13th century and was borrowed from the Old French word chanel (a variant form of chenel 'canal'). By the middle of the fifteenth century, an Italian map based on Ptolemy 's description named the sea as Britanicus Oceanus nunc Canalites Anglie (Ocean of the Britons but now English Channel). The map is possibly the first recorded use of the term English Channel and

11550-523: Was in common usage in England . Following the Acts of Union 1707 , this was replaced in official maps and documents with British Channel or British Sea for much of the next century. However, the term English Channel remained popular and was finally in official usage by the nineteenth century. The French name la Manche has been used since at least the 17th century. The name is usually said to refer to

11660-495: Was re-sited with improved mines and more effective nets, aided by regular patrols by small warships equipped with powerful searchlights. A German attack on these vessels resulted in the Battle of Dover Strait in 1917 . A much more ambitious attempt to improve the barrage, by installing eight massive concrete towers across the strait was called the Admiralty M-N Scheme but only two towers were nearing completion at

11770-552: Was the Narrow Seas , a collective term for the channel and North Sea . As England (followed by Great Britain and the United Kingdom) claimed sovereignty over the sea, a Royal Navy Admiral was appointed with maintaining duties in the two seas. The office was maintained until 1822, when several European nations (including the United Kingdom) adopted a three-mile (4.8 km) limit to territorial waters. The word channel

11880-506: 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

11990-538: Was to become a far greater threat to Britain. The Dover Patrol , set up just before the war started, escorted cross-Channel troopships and prevented submarines from sailing in the Channel, obliging them to travel to the Atlantic via the much longer route around Scotland. On land, the German army attempted to capture French Channel ports in the Race to the Sea but although the trenches are often said to have stretched "from

12100-598: 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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