# lighthouse

Former lighthouse, today (unlit) landmark Roter Sand

A lighthouse is a tower that carries a light . Lighthouses are navigation signs that can be seen from afar, especially at night (through the beacons and as bearing marks) and are used to determine position , warn of shallows or mark the fairway .

## technology

### Construction

The Neuwerk lighthouse from 1310 is the oldest secular structure on the German coast, the attached lamp house dates from 1814.

The construction of the lighthouses is very diverse. In pre-industrial times, lighthouses were mostly bricked up. In historical tower constructions there were sometimes living and working rooms for the operating personnel, which were often supplemented by ancillary buildings. Since the job of the lighthouse attendant is no longer exercised due to automation, the former workrooms are used for other tasks today. With the advent of metal construction, it became possible to build lightweight, wind-resistant structures made of cast iron, forged steel, and finally cast and rolled steel . At first, steel frameworks predominated , later tubular and mast-like constructions. Nowadays, many such structures are made of reinforced concrete , buildings made of fiberglass-reinforced plastic such as Kahler Sand on the Elbe remained the exception. The lighting system and optics are usually attached to larger buildings; they are referred to as lamp houses or lanterns .

Until the late 20th century, numerous lightships were positioned in the North and Baltic Seas, where it was not possible to erect lighthouses , with beacons up to 45 meters high. Today only two lightship positions are maintained by the German Waterways and Shipping Administration. The most famous German lightship was the Elbe 1 .

In narrow fairways, leading lights are set up from two synchronized lights of different heights.

#### Tower height and fire height

For short distances, a low height is sufficient, such as the Bunthaus beacon

The height of the fire is the distance between the water level and the fire . For cost reasons, it makes sense to erect the lighthouse on a hill near the coast, because the tower height can be lower with the same fire height. In extreme cases, however, it can make more sense to build a lighthouse at a lower point if it means that it is in clearer layers of air. The old lighthouse at Cape Point in South Africa , 238 m high, was replaced in 1911 by the new lighthouse located lower down , as the old tower was too often in high fog and its light was therefore not as visible as originally assumed. The lighthouse of Jeddah in Saudi Arabia has a tower height of 133 meters. The highest German lighting is 114 m above the Baltic Sea on the Hotel "Maritim" in Lübeck-Travemünde . At 65 meters high, the three-legged steel lattice tower Lighthouse Campen at the mouth of the Ems is Germany's tallest lighthouse. As part of the deepening of the Elbe, a new leading light line is being planned with a tower height of almost 100 meters. One of the smallest lighthouses likely the former beacon Bunthaus (1914-1977) on the colored houses tip ( lower Elbe in Hamburg to be) with 6.95 meters tower height.

### optics

Identification (light character) using the example of the Ameland lighthouse during a 30-second interval
Animation of the light character of the Ameland lighthouse

#### Bundling

Fresnel lenses have been used as beacon optics since around 1820 , which have a compact design, relatively low weight and a high opening angle . Several lenses are set up vertically and arranged next to each other on a circle. The circle is rotatable and the bundles of lenses create a characteristic blinking pattern. Color filters are also used for additional coding. Due to the rotation time , each tower has a specific return and identifier , which are published in the beacon directory and on nautical charts. If necessary, the identification is extended by color filters aligned with the fairway. The rotation of the lens creates a rhythmic colored flashing.

#### Light sources

Initially open wood and coal fires and later oil lamps were used as light sources. The Argand lamp prevailed from around 1800. Later they used incandescent gas and even developed an automatic mantle changer. Petroleum was used as fuel , which had previously been vaporized by the heat of the lamp (for the principle, see also high-intensity lamp ).

From 1858 carbon arc lamps were tested. An automatic readjustment of the carbon pins was developed, but it still required a certain amount of maintenance and polluted exhaust air.

Incandescent lamps were used from the 1920s . In the event of failure, a replacement lamp swiveled into focus. Metal halide lamps are used today .

### Range

The range of most beacons is between 5 and 20 nautical miles , depending on their design and circumstances . It depends on various factors: The geometric or geographical visibility is limited by the curvature of the earth and is influenced by the height positions of the observer and the beacon as well as geographical obstacles. Added to this are the luminous intensity and color of the light source as well as the quality of the optics. In addition, the weather and the resulting visibility conditions limit the range. The influence of the weather is taken into account using a so-called visibility scale . In unfavorable weather conditions, the light intensity is reduced by precipitation, snowfall or fog. Ultimately, the range represents a compromise between what is technically possible and the effort for construction, power supply and maintenance costs .

Because of the curvature of the earth , the theoretical range increases with the root of the tower height and the root of the navigator's eye height . If a beacon appears or disappears on the nautical horizon ("in the chin "), its distance can easily be calculated and the location of the ship can be determined. The formula can be derived using the Pythagorean theorem . If the heights of the beacon and navigator are low in relation to the earth's radius, it is in a simplified approximation:

${\ displaystyle {\ text {Distance in nautical miles}} \ approx 1 {,} 9274 \ cdot \ left ({\ sqrt {\ text {Eye level in meters}}} + {\ sqrt {\ text {Fire height in meters}} } \ right)}$

## History of the lighthouse

Reconstruction of the Pharos of Alexandria
13th century candle lantern

How the history of the lighthouses began is not known. What is certain is that there was already brisk sea ​​trade in the eastern Mediterranean long before the birth of Christ - and probably also beacons to find your home port in the dark .

### Antiquity

At least two ancient lighting structures have survived, both from around 300 BC. Created: The Greek colossus of Rhodes and the Egyptian Pharos of Alexandria (erected between 299 and 279 BC, height 115 to 160 m). However, it is uncertain whether the Colossus of Rhodes really served as a beacon. It is said to have stood for about eight decades until it was discovered in 224 BC. Chr. Collapsed. The Egyptian lighthouse, on the other hand, shone for over 1,600 years and collapsed in an earthquake in 1303 . He is the namesake of the term lighthouse in the Romance languages ​​and thus lighthouse science , which is now known as pharology .

The Tower of Hercules was built by the Romans in A Coruña, Galicia ( Spain ). It was completed in 110 AD by Gaius Sevius Lupus, was originally 36 m high and measured 18 m × 18 m at the base. In 1791 it was expanded and given a classicist cover. The tower, which is still in use today, is the oldest functioning lighthouse in the world and has been a UNESCO World Heritage Site since 2009 . Older towers from Roman times such as that of Dover are still extant in many cases, but sometimes only as ruins.

Away from the high cultures, seafaring initially looked for simpler ways to “illuminate” the seafarers. Torches and small beach fires showed the fishermen their way at night. Monks recommended their operation as a godly task.

### Hanseatic period

From the 13th century onwards, the Hanseatic cities on the Baltic coast built access fires, often as candle lanterns on offshore islands, for example Lübeck (in Travemünde ), Wismar , Rostock (in Warnemünde ), Stralsund (on Gellen ), Greifswald and Danzig . The existing port sign in Travemünde was given imperial privileges in 1226. In 1299 Hamburg received the North Sea island of Neuwerk to build a fireblood there. However, it can only be proven from 1644 - at first the Hanseatic city was primarily concerned with securing the Elbe approach. Around 1625 a permanent beacon followed on Wangerooge ; however, the use of the old west tower did not prove successful.

### Early modern age

The beacons were significantly improved in 1782 by the Geneva physicist Aimé Argand (1750–1803) with the (hollow-wick lamp ) Argand lamp , a petroleum lamp . It was only later that gas incandescent lights caught on. Finally, on behalf of the French government , Augustin Jean Fresnel (1788–1827) developed a beam of light using special lenses . The Fresnel lenses increased the range of the beacons considerably.

The regularly blinking lighthouse was invented by François Antoine Henri Descroizilles (1751-1825). A watchmaker from the northern French port city of Dieppe made the mechanism; the first lighthouse equipped with it went into operation in May 1787 at the boat jetty in Dieppe.

In the 18th century, the lamp maker Thomas Smith founded a family of lighthouse builders in Edinburgh , which, especially in Scotland , built more than a dozen lighthouses over four generations.

### distribution

Lighthouses can be found on all continents, including Antarctica, and are mainly located on the coast of the sea. There are also some lighthouses

The highest lighthouse in the world is Faro de Puno in Peru (3810 meters altitude + 9 meters structure height). The only lighthouse in Bavaria is the New Lighthouse in Lindau (previously the Mangturm a few meters away).

### Current change in use

Modern digital navigation aids diminish the current importance of lighthouses, but cannot completely replace visual navigation signs. In the event of a failure of the GPS , the electronics or the power supply, lighthouses represent indispensable protection, which is why lighthouses must also be maintained in the future.

The former staff rooms and the viewing platform , on the other hand, are no longer necessary for the lighthouse operation. Today they are used for tourist or gastronomic purposes, some towers also serve as accommodation or can be rented for wedding ceremonies .

## Light signal vs. lighting

Lighthouses in the narrower sense serve to permanently mark a location and, in order to be identifiable, send out an individual light signal that, viewed from a distant point, consists of a rhythmic sequence of light flashes. Realized, for example, with several converging lenses that rotate as a ring around a very small light source. In air clouded by fog, for example, a sector with irradiation can be seen wiping past. In order to reach far, the light is not only bundled into a narrow sector (= visible as a short flash), but also close to the horizontal plane, possibly around a very obtuse cone due to the curvature of the earth. The signal can be controlled, dimmed and / or colored in such a way that it is perceived differently depending on the direction (horizontal angle) and thus offers additional information.

In exceptional cases, lighthouses can also be used for lighting purposes. Light sources are positioned so high that their light hits the ground at a sufficiently large angle, even at a distance, to facilitate human work and movement. So served z. As the two fire towers of Castle Luberegg along the Danube River in Emmersdorf (Lower Austria) for 1780 to 1811 for illuminating the bank so per timber glut incoming timber also had a good night to be loaded onto barges. The towers, which are about 120 m apart, made it possible to illuminate the area between them with little shadow.

## Metaphors

In a figurative sense , projects that send a signal or serve as a role model are referred to as lighthouse projects .

In the English-speaking world, the modern legend of the lighthouse and warship is a popular metaphor for the occasional inflexibility of great powers.

## literature

• Monika Bergmann: Lexicon of the lighthouses . Komet, Cologne 2008, ISBN 978-3-89836-827-8 .
• Gerhard Wiedemann (ed.), Johannes Braun, Hans Joachim Haase: The German sea mark system. 1850–1990, between sailing and container shipping [in collaboration with the German Maritime Museum in Bremerhaven]. DSV-Verlag, Hamburg 1998, ISBN 3-88412-275-4 .
• Jean Guichard (photos), Vincent Guigueno (text): Lighthouses (original title: Phares , translated by Christiane Hauert). DK Edition Maritim, Hamburg 2007, ISBN 978-3-89225-575-8 .
• Ian Penberthy: The 75 most impressive lighthouses in the world (original title: Lighthouses - Man-made Wonders , translated by Annerose Sieck). Tosa, Vienna 2009, ISBN 978-3-85003-388-6 .
• Jürgen Voss: Lights on the horizon - lighthouses between day and night . DK Edition Maritim, Hamburg 2003, ISBN 978-3-89225-482-9 .
• Vera Stehlin: Lighthouse. In: Reallexikon für antiquity and Christianity . Volume 22, Hiersemann, Stuttgart 2008, ISBN 978-3-7772-0825-1 , Sp. 1219-1230.
• RG Grant: Guardian of the Sea. The history of the lighthouses (original title: Sentinels of the sea , translated by Heinrich Degen). DuMont, 2018, ISBN 978-3-8321-9936-4 .

Stamp series

Events

Commons : Lighthouses  - Album with pictures, videos and audio files
Wiktionary: lighthouse  - explanations of meanings, word origins, synonyms, translations

## Individual evidence

1. Lighthouse Camping on the side of the Emden Waterways and Shipping Office.
2. a b c http://ralflampe.de/030686/LEUCHTF/Luchtert.htm Clemens Volkmann: Leuchtfeuer und Technik, profile work in physics, accessed on December 20, 2019
3. The North Sea: a natural and cultural history , Richard Pott, CH Beck, 2003 - “The Pharos off Alexandria (...) was probably the oldest known lighthouse on earth, (...) but it is not only about the“ lighthouse science ”, the“ pharology », Given the name (...)"
4. ^ A b Clément Duval: François Descroizilles, the Inventor of Volumetric Analysis . In: American Chemical Society ACS (Ed.): Journal of Chemical Education . tape 28 , no. 10 . ACS Publications, October 1951, ISSN  0021-9584 , p. 508-519 , doi : 10.1021 / ed028p508 : “this gave Descroizilles the idea of ​​a flashing lighthouse. A clockmaker of Dieppe […] constructed the mechanism. The first wooden lighthouse was operating at the end of the main jetty in May 1787. "
5. Jules-Adrien de Lérue: Notice sur Descroizilles (François-Antoine-Henri) . chimiste, ne à Dieppe, et sur les membres de sa famille. Ed .: C.-F. Lapierre Rouen. 1875, p. 7–8 ( online at Gallica Bibliothèque nationale de France ): “on pourrait construire des phares qui s'éclipseraient ainsi. Le nombre des révolutions dans un temps donné indiquerait aux navires le point où ils seraient. "
6. https://www.welt.de/print-welt/article484922/Das-Unikum-vom-Bodensee.html
7. https://www.br.de/nachrichten/bayern/lieblingsplatz-lindau-bayerns-einziger-leuchtturm,RZm40bK
8. https://www.marcopolo.de/reisefuehrer-tipps/lindau-bodensee/alter-leuchtturm-poi-122429536.html