4.2 From Ancient South-Pointing Chariot to Modern Navigation System
203
a light column, whose transmission distance was increased greatly. The modern
lighthouses use incandescent electric lamp as the light source, the center of the
luminescent body is located at the focal point of spotlight lens. The light source
radiates the spherical light through the spotlight lens to become light beam, whose
range can reach 30 nautical miles and whose intensity equates to the light from
burning hundreds of millions of candles simultaneously. The navigation lighthouse
usually uses white light, but also uses the flash with different colors, and particularly
the light that warns the dangerous directions near the port, mostly uses red, green or
blue, so that the ships that are about to enter the port can clearly decide whether the
navigation is safe or not.
According to ancient Greek poetry, the beacons with navigation function had been
built along the Mediterranean coast in about 660 B.C. These are the earliest “Lighthouses” of human civilization. In 280 B.C., an Egyptian Royal wedding ceremony
ship hit a reef and sank as it was sailing into the harbor of Alexandria. For this
reason, Egyptian King Ptolemy II Philadelphus (283–246 B.C.) ordered to build a
navigation lighthouse at the eastern end of the island called Pharos near the harbor
of Alexandria. It is the famous Pharos Lighthouse, also known as the Lighthouse of
Alexandria, which has been listed as one of the Seven Wonders built in ancient times
along the eastern Mediterranean coast. The Pharos Lighthouse was designed and
built by the ancient Greek architect Sostratus of Cnidus, and made of white marble
with three layers. The lower, middle and upper layers were quadrangular, octagonal
and cylindrical shape, respectively. The statue of Poseidon, a God of the sea, was
mounted on the top of the Lighthouse. A large fire basin was installed below the statue
at the top of the Lighthouse. Behind the fire basin, there was a polished and bright
granite slab with reflective function. At night, the fire light can be reflected to far sea
surface to guide ship’s voyage direction. The Pharos Lighthouse had been estimated
to be 137 m in overall height, and had been a symbol of the great reputation of the
Egyptian monarch. It has stood for more than 1500 years at the harbor of Alexandria, and was completely destroyed by two major earthquakes in 1303 and 1323. In
May 2015, the Egyptian government was planning to rebuild the Pharos Lighthouse.
Up to now, “Pharos” in many European languages still means “lighthouse”, from
which the English word “Pharology” originates, which means the scientific studies
on lighthouses and signal lights, and their construction and illumination.
Afterward, the ancient Romans built a series of lighthouses and created the earliest
lighthouse network system. Arabs, Indians and Chinese also gradually mastered
the construction technology of lighthouse. At present, the oldest and still in use
lighthouse in the world is the Tower of Hercules built at the entrance of La Coruna
Harbor in northwestern Spain, by the ancient Romans in the late first century A.D. The
Spanish government has repaired and rebuilt it many times. The Tower of Hercules
was built on 57-m-high rock, with a height of 55 m and a light range of 23 nautical
miles. In 2009, the Tower of Hercules, as only architecture of lighthouses, was
listed in the World Cultural Heritage List. Moreover, located at the mouth of the
Gironde Estuary in southwestern France, the Cordouan Lighthouse is the oldest
existing lighthouse in France, the tenth tallest traditional lighthouse in the world,
with a height of 68 m, which has the design style of Renaissance and the reputation
203
a light column, whose transmission distance was increased greatly. The modern
lighthouses use incandescent electric lamp as the light source, the center of the
luminescent body is located at the focal point of spotlight lens. The light source
radiates the spherical light through the spotlight lens to become light beam, whose
range can reach 30 nautical miles and whose intensity equates to the light from
burning hundreds of millions of candles simultaneously. The navigation lighthouse
usually uses white light, but also uses the flash with different colors, and particularly
the light that warns the dangerous directions near the port, mostly uses red, green or
blue, so that the ships that are about to enter the port can clearly decide whether the
navigation is safe or not.
According to ancient Greek poetry, the beacons with navigation function had been
built along the Mediterranean coast in about 660 B.C. These are the earliest “Lighthouses” of human civilization. In 280 B.C., an Egyptian Royal wedding ceremony
ship hit a reef and sank as it was sailing into the harbor of Alexandria. For this
reason, Egyptian King Ptolemy II Philadelphus (283–246 B.C.) ordered to build a
navigation lighthouse at the eastern end of the island called Pharos near the harbor
of Alexandria. It is the famous Pharos Lighthouse, also known as the Lighthouse of
Alexandria, which has been listed as one of the Seven Wonders built in ancient times
along the eastern Mediterranean coast. The Pharos Lighthouse was designed and
built by the ancient Greek architect Sostratus of Cnidus, and made of white marble
with three layers. The lower, middle and upper layers were quadrangular, octagonal
and cylindrical shape, respectively. The statue of Poseidon, a God of the sea, was
mounted on the top of the Lighthouse. A large fire basin was installed below the statue
at the top of the Lighthouse. Behind the fire basin, there was a polished and bright
granite slab with reflective function. At night, the fire light can be reflected to far sea
surface to guide ship’s voyage direction. The Pharos Lighthouse had been estimated
to be 137 m in overall height, and had been a symbol of the great reputation of the
Egyptian monarch. It has stood for more than 1500 years at the harbor of Alexandria, and was completely destroyed by two major earthquakes in 1303 and 1323. In
May 2015, the Egyptian government was planning to rebuild the Pharos Lighthouse.
Up to now, “Pharos” in many European languages still means “lighthouse”, from
which the English word “Pharology” originates, which means the scientific studies
on lighthouses and signal lights, and their construction and illumination.
Afterward, the ancient Romans built a series of lighthouses and created the earliest
lighthouse network system. Arabs, Indians and Chinese also gradually mastered
the construction technology of lighthouse. At present, the oldest and still in use
lighthouse in the world is the Tower of Hercules built at the entrance of La Coruna
Harbor in northwestern Spain, by the ancient Romans in the late first century A.D. The
Spanish government has repaired and rebuilt it many times. The Tower of Hercules
was built on 57-m-high rock, with a height of 55 m and a light range of 23 nautical
miles. In 2009, the Tower of Hercules, as only architecture of lighthouses, was
listed in the World Cultural Heritage List. Moreover, located at the mouth of the
Gironde Estuary in southwestern France, the Cordouan Lighthouse is the oldest
existing lighthouse in France, the tenth tallest traditional lighthouse in the world,
with a height of 68 m, which has the design style of Renaissance and the reputation