lighthouse

Lighthouse is the commanding height of the island, is a landmark building on the island, is the fishermen's guard lamp. Climb the observation tower on the top of the tower and look at the boundless blue coast. When the weather is good, you can still vaguely see Beihai City on the other side of the distance.

lighthouse

This entry is compiled and applied by "popular science China" Science Encyclopedia

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The lighthouse is a high tower building. The lighting equipment should be installed at the top of the tower. It should be noted that the lighthouse should have a specific architectural shape, which is easy for ships to distinguish. At the same time, it should become one of the highest points of the port. As the surface of the earth is curved, the tower body must have sufficient height, so that the light energy of the light can be seen by long-distance ships, and the general sight distance is 15-25 nautical miles; however, the light should not be too high, so as not to be covered by high clouds and fog. According to the size of the lighthouse and the characteristics of the location, lighthouses can be guarded or unattended, and important lighthouses should be guarded.

Basic knowledge

Lighthouse is a building located on the coast, port or river to guide the direction of ships. Most of the lighthouses are similar to the shape of the tower, through the lens system on the top of the tower, the light will shine to the sea. Before electricity appeared, fire was often used as light source.

Lighthouse structure

Tower body

The lighthouse is composed of lamp and tower body. The tower body can be constructed by various building materials, mainly to adapt to and resist the harsh natural conditions such as wind and waves, so as to maintain its own stability and durability. The height of the tower should meet the requirements of light range.

lamps and lanterns

The lamp is composed of two basic parts: light emitter and light radiator. The light source of modern lighthouse mainly uses electricity. The center of the light emitter is located in the focus of the concentrating lens. The light radiated by the light source is spherical and becomes a parallel beam with a certain diffusion angle through the concentrating lens. The range of the lighthouse can reach about 30 nautical miles, and the intensity of light can reach hundreds of millions of candlelight. Lighting has flash, fixed light and dim light, etc. The light colors are red, white or green, white. It is usually indicated by red and green light that there are obstacles in the light arc.

The symbolic meaning of Lighthouse

The former lighthouse symbolized hope because it was lit by fire.

Light source of Lighthouse

In old lighthouses, to conserve energy and concentrate light sources:

Light is emitted horizontally.

The light level on the top of the tower remains unchanged, and a rotating device is set on the top of the tower to ensure that the light can be seen in every direction around.

In the very old lighthouse, the kerosene lamp is used as the light source, and the person in charge of the lighthouse manually operates the spring device to rotate the lens system of concentrating light. The lens system often floats in mercury to prevent friction. In modern lighthouses are lights and clockwork, powered from outside, and equipped with diesel powered generators to power the lives of the lighthouse owners. Some lighthouses are powered by solar power.

If you want to increase the brightness, you need a very large lens, even the lighthouse may not be able to bear the weight. Fresnel lens came into being. Its design greatly reduces the weight and capacity of the lens, while the focal distance remains unchanged. Some lighthouses, such as Cape race lighthouse in Newfoundland and Makapu'u Point Lighthouse in Hawaii, use another hyperradiant Fresnel lens specially developed by chance brothers.

In the modern automatic lighthouse, the rotating lens emits very bright light from the omni-directional system (it is no longer large space to collect more light).

In many design and observation lighthouses, people prefer to see continuous but weak light, so only a short time interval after the weak light. These instantaneous bright lighthouses are arranged to be special lighthouses that emit interval light. For example, the Scheveningen lighthouse in the Netherlands converts light intensity between 2.5 and 7.5 seconds.

High pole Lighthouse

The lamp pole of high pole lamp in China is mostly made of steel. There are three types of steel poles: four column, three column and single pole. The single pole type is used most, because the single pole type covers a small area. The height of the American steel lamp pole is mostly 25m and 30m, and the highest is 40m. The steel lamp pole was made into straight pole in the past few years.

Since 1986, due to the improvement of processing technology, some of them have been replaced by the tapered rod with small upper end and large bottom end and variable diameter. According to the different height, the outer diameter of the rod varies from 330mm to 900mm, and the thickness of the rod wall varies from 8mm to 14mm. According to the different modeling requirements, there are dozens of lamp caps for high pole lighting lighthouses, such as flying hat type, hat type, etc It's most commonly used. Small factories have fixed products, while large ones need to be specially designed and manufactured.

The foundation of high pole lighthouse is generally reinforced concrete circular plate foundation. In order to resist wind and earthquake, the buried depth of circular plate foundation is generally not less than 2.5m. The foundation and the lamp pole are connected by a blue plate.

Practical use

Escort lighting

Lighthouse is a kind of tower shaped luminous navigation mark built near the key parts of the channel. It is a kind of fixed navigation mark. Its basic function is to guide ships to navigate or indicate dangerous areas (commonly used to mark dangerous coasts, dangerous sandbanks or reefs and the channel leading to the mouth of the port).

Geographical coordinates

With the rapid development of science and technology and the establishment of integrated navigation system of radar transponder, DGPS system and AIS automatic identification system, the navigation function of Lighthouse is becoming weaker and weaker, and its navigation value is decreasing day by day. However, it has potential historical and cultural value and has become a popular human geographical coordinate in various countries.

military defense

The lighthouse is said to be a beacon tower on the sea. In the past, it was also used for military purposes to carry out coastal defense lookout and prevent illegal immigration. Generally, the lighthouse is close to the fort, Castle and other defense facilities.

In addition, lighthouse can also play the role of psychological warfare.

Located on the border between the DPRK and the ROK, the lighthouse is only 3 km away from the DPRK. Its history dates back to 1954. At that time, in order to convey the joy of Christmas to North Korean residents, a large pine tree was decorated as a Christmas tree. In 1971, a 30 meter high Christmas lighthouse was built here, which can be seen from afar. Hundreds of small light bulbs were decorated on the lighthouse, and the Christmas lighthouse was lit in December every year. It is said that the light of the lighthouse can also be seen with the naked eye in Kaesong, North Korea, 2 or 3 kilometers away. For a long time, North Korea has urged South Korea to dismantle the Christmas tree on aijifeng, and has made a serious protest against lighting the tree on aijifeng. In June 2004, North and South Korea held a general level military talks, which North Korea protested seriously. Later, during the talks, an agreement was reached on stopping propaganda activities along the military border, including stopping lighting the Lighthouse of aijo peak. However, with the North Korea and South Korea's bad relations, South Korea re lit the eicho peak lighthouse at the end of 2010.

Declaration of sovereignty

Lighthouses, sentries and boundary markers are often regarded as symbols of sovereignty in disputed waters.

At the end of 2010, China built a landmark and lighthouse type landmark on the basis of the territorial sea in the East China Sea, which provides a theoretical basis for the delimitation of China's territorial sea baseline. Earlier, Japan also erected a lighthouse on the so-called "chongzhiniao reef" to pledge sovereignty.

Development history

Construction history

In about 270 BC, Ptolemy II appointed the Greek architect sothratus of nidos to build the world's first lighthouse at the eastern end of the island of Faros. It can not only guide the ships entering Alexandria, but also become a huge symbol of the great reputation of the revived Egyptian monarch. The Pharos Lighthouse became one of the seven wonders of the ancient world.

The ancient Romans built a series of lighthouses, thus creating the earliest lighthouse network system. The earliest lighthouse in this system was built in AD 50. The Roman Emperor Claudius ordered the construction of a lighthouse in ostia, the port city of Rome. There was a 320 foot long and 65 foot wide old wooden boat in the port. The boat was built with stones and binders to form an artificial island. The lighthouse was built on the island, with a total of four floors. The Lighthouse of ostia remained until the 15th century.

Later, Arabs, Indians and Chinese also learned this method to ensure the safety of sailing at sea, and built lighthouses on their surrounding coasts. The first lighthouse in China was the Chongwu Lighthouse (1387), which was built in Huian County, Fujian Province. In the 10th year of Yongle (1412) of the Ming Dynasty, the government built a mound on the beach southeast of Liuhekou in the Yangtze River Estuary, which was "hundreds of feet square and more than 30 feet high, with smoke in the daytime and fire in the night" to guide ships into and out of the Yangtze River Estuary. This is a precedent for China's government funded construction of navigation aids.

After the signing of the Sino British Treaty of Tianjin in 1858, it was stipulated that "floating piles, boats, pagodas and watchtowers should be set up at each port of the trade, and they should be built by consuls and local officials at the same time", which opened the way for the construction of lighthouses in modern China.

Chinese PinYin : Deng Ta