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Su Song

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Su Song was a brilliant polymath from the Song dynasty in China. A polymath is a person who is an expert in many different fields. Su Song excelled in many subjects, including mathematics, astronomy, and metallurgy. He was also a skilled statesman and a high-ranking government official. He lived from 1020 to 1101. During his life, he rose to many important positions. He served as an Ambassador and the President of the Ministry of Personnel. He even held the title of Vice President of the Chancellery Secretariat.

SuSongClock1
SuSongClock1

One of Su Song's greatest achievements was a massive hydro-mechanical astronomical clock tower. This tower was located in the capital city of Kaifeng. It was about 40 feet tall. The project was sponsored by Emperor Zhezong of Song in 1086. The Emperor wanted to show scientific superiority over the Liao dynasty to the north. Su Song worked with other experts, like the mathematician Han Gonglian. They first built a small wooden pilot model in 1088. This allowed them to test the intricate parts. By 1090, the bronze components were cast. The entire tower was completed in 1094.

Bulletin - United States National Museum (1959) (20481431946)
Bulletin - United States National Museum (1959) (20481431946)

The clock tower used a complex system of moving parts. It utilized a hydro-mechanical mechanism, which means it was powered by water. At the top sat a rotating armillary sphere. An armillary sphere is a model of objects in the sky. This sphere was very heavy, weighing between 10 and 20 tons. The tower also featured a 4.5-foot diameter bronze celestial globe in the middle. To keep time, the machine used an escapement mechanism. An escapement is a device that controls the release of energy in a clock. This mechanism was an early version of the kind used in later clocks.

SuSongClock2
SuSongClock2

Inside the tower, the machinery was quite advanced. It included the oldest known endless power-transmitting chain drive. Su Song called this the *tian ti*, or "celestial ladder."

Chain drive, Su Song's book of 1092
Chain drive, Su Song's book of 1092

The tower also used sophisticated oblique gears. To show the time, the tower used 133 different clock jacks. These were mechanical figures that could indicate and sound the hours. These figures would emerge from doors to ring bells, beat drums, or show plaques. This made the clock a very visual and loud instrument.

SuSongClock5
SuSongClock5

Su Song was also a famous astronomer and cartographer. He created a celestial atlas consisting of five separate star maps. These maps used an equidistant cylindrical projection. This is a way of flattening a sphere onto a flat surface. His maps were very accurate regarding north polar distances. He even used findings from his contemporary, the astronomer Shen Kuo. One of Su Song's maps was accurate to within 3 degrees of the pole star. His star maps are significant because they are the oldest extant star maps in printed form.

Su Song Star Map 1
Su Song Star Map 1

Beyond the stars, Su Song studied the natural world through pharmacology. He helped edit the *Bencao Tujing*, a book about medicine. This treatise covered botany, zoology, and mineralogy. He described many minerals, such as the deep red mineral realgar.

He even wrote about how to use different types of mica for digestion. He also studied animals, like various species of crabs. He noted where specific freshwater crabs could be found in different rivers and marshes. His scientific work was so detailed that it was copied by later doctors in the Ming dynasty.

Su Song Star Map 2
Su Song Star Map 2

Su Song's life was full of many different responsibilities. He was a diplomat who traveled to the Liao dynasty. He used his knowledge of cartography, or map-making, to settle border disputes. He also wrote a massive 200-volume history of diplomatic relations. Sadly, his great clock tower did not last forever. In 1127, an invading Jurchen army dismantled the tower. People tried to reassemble it later. However, the tower was never successfully reinstated. Even without the tower, his written work, the *Xinyi Xiangfayao*, preserved his amazing ideas for the world.

Clock Tower from Su Song's Book desmear
Clock Tower from Su Song's Book desmear
647 words

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🖼️ Images & Media (13)
File:Clock Tower from Su Song's Book desmear.JPG
Clock Tower from Su Song's Book desmear.JPG
File:Bulletin - United States National Museum (1959) (20481431946).jpg
Bulletin - United States National Museum...
File:SuSongClock1.JPG
SuSongClock1.JPG
File:Su Song Star Map 1.JPG
Su Song Star Map 1.JPG
File:Realgar, 1Rumunia1, Baia Sprie.jpg
Realgar, 1Rumunia1, Baia Sprie.jpg
File:SuSongClock2.JPG
SuSongClock2.JPG
File:Su Song Star Map 2.JPG
Su Song Star Map 2.JPG
File:Chain drive, Su Song's book of 1092.jpg
Chain drive, Su Song's book of 1092.jpg
File:SuSongClock3.JPG
SuSongClock3.JPG
File:SuSongClock4.JPG
SuSongClock4.JPG
File:SuSongClock5.JPG
SuSongClock5.JPG
File:Chain.gif
Chain.gif

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