He improved the Grand Canal, built a human-made lake (Kunming lake), created one of the most accurate calendars in history, invented some of the most accurate clocks during his time, and made many other contributions to math, astronomy, and hydraulics (water engineering).
He was born in 1231 in Xingtai, Hebei province. His family was poor. He grandfather, Guo Yong, was famous for his study of the Five Classics to astronomy, mathematics, and hydraulics. Guo Shoujing was a child prodigy. As a teenager, he learned how to build a water clock. He then improved it. His new invention was called the lotus clepsydra (a bowl shaped like a lotus flower that water dripped into). At 16 he began to study math and from there hydraulics and astronomy.
At 20, Guo became a hydraulic engineer and government official. He helped fix a bridge over the Dahuoquan River.
In the late 1250s, Kublai Khan (of the Mongol Empire, Yuan dynasty) thought hydraulic engineering, irrigation, and water transport would help the country and people. He sent Liu Bingzhong and his student Guo to improve irrigation systems between Dadu (now Beijing) and the Yellow River.
Guo helped build a 30 km canal from Baifu spring in the Shenshan Mountain to Dadu,
The Grand Canal linked the Yangzi river, the Huai, and Yellow river since the early 7th century. Guo helped extend it to Dadu 1292–93.
It worked. Kublai Khan was happy, and Guo did similar things for the rest of the empire. He was promoted to chief advisor of hydraulics, mathematics, and astronomy.
He created a human-made Kunming Lake in Beijing. This was one of his most memorable engineering feats.
The lake provided water for all areas surrounding Beijing and led to the best grain transport system in the world.
He built other reservoirs, thereby allowing people in inner China to access to fresh water for planting, drinking, and trading.
For irrigation, he provided hydraulics systems which distributed water equally and quickly, which allowed communities to trade more effectively, and therefore prosper.
In 1292, he became the head of the Water Works Bureau.
Guo invented many astronomy devices: the gnomon, the square table, the armilla, and a water powered armillary sphere called the Ling Long Yi.
Even when young Guo was revolutionizing old inventions. His clocks, watches, irrigation, reservoirs, and equilibrium stations were the most accurate of his time, allowing for an extremely accurate recording of time.
Kublai Khan noticed Guo was a genius in astronomy. So he asked Guo, Zhang, and Wang Xun to build a very accurate calendar. It would be the most accurate of its time. They built 27 observatories in the empire to collect data for calculations.
In 1280, Guo finished the calendar, calculating a year to be 365.2425 days, just 26 seconds off modern measurements. He invented many tools in the process.
The calendar revolutionized China and the world. It allowed more accurate recording of history, gave a sense of unification, and helped later emperors rule over China. His calendar would be used for the next 363 years, the longest a Chinese calendar has been used in history.
Guo was also able to more accurately establish the location of celestial bodies and the angles of the Sun relative to Earth. He invented a new type of compass, helping people find north using the stars instead of magnets.
In 1283, Guo was promoted to director of the Observatory in Beijing.
Guo’s work in mathematics was regarded as the most knowledgeable for 400 years. Throughout his life he worked a lot on spherical trigonometry, using a system of approximation to find arc lengths and angles. He approximated pi was equal to 3. But this allowed him to solve some equations much faster and more accurately than if he said pi was 3.14...
He also used mathematical functions for spherical trigonometry, building upon the knowledge of Shen Kuo's (1031–1095).
The next important work in trigonometry would only be printed 300 years later by Xu Guangqi in 1607, during the Ming Dynasty.
Tang Shunzhi 唐順之 (1507-1560) said Guo's work was an example of "practical scholarship" (applying advanced knowledge to solve practical problems).
Guo influenced the Changzhou School of Thought and spread of "evidential learning" (learning through experience).
A number of things are named after Guo, including the Asteroid 2012 Guo Shou-Jing and the Large Sky Area Multi-Object Fibre Spectroscopic Telescope near Beijing.
Grand Canal (China)
The Grand Canal or Dayunhe or Jing–Hang Grand Canal () is the longest and oldest canal and artificial river in the world.
It starts in Beijing; passes through Tianjin, Hebei, Shandong, Jiangsu and Zhejiang; and ends in Hangzhou.
It connects China's two longest rivers: the Yellow River and the Yangzi.
The oldest parts of the canal were built during the 5th century BC.
The Sui dynasty (581–618 AD) added some other parts. Between 1271–1633, the Yuan dynasty (through Guo Shoujing and others) and the Ming dynasty improved it and built parts to direct water to Beijing.
The total length is . Its greatest height is 42 m (138 ft) near the Shandong mountains.
Song Dynasty (960–1279) engineer Qiao Weiyue invented the pound lock in the 10th century. This allowed ships to travel higher and lower through the canal.
The canal amazed many people throughout history including Japanese monk Ennin (794–864), Persian historian Rashid al-Din (1247–1318), Korean official Choe Bu (1454–1504), and Italian missionary Matteo Ricci (1552–1610).
Historically, flooding of the Yellow River threatened to break the canal. During wartime the canal was even used as a weapon: the dikes of the Yellow River were sometimes broken to flood the enemy troops. But this caused disasters and hurt the economy.
The Canal has greatly improved China's economy and increased trade between the north and south. It is still used heavily to this day.
It is a UNESCO World Heritage Site.
Slavery in the United States
Slavery in the United States was the legal institution of human slavery in the United States. Slaves were mostly Africans and African Americans. Slavery existed in the United States of America in the 18th and 19th centuries. Slavery existed in British America from early colonial days. Slavery was legal in all Thirteen Colonies at the time of the Declaration of Independence in 1776. It lasted in about half the states until 1865. This was when it was banned in the entire country by the Thirteenth Amendment.
By the time of the American Revolution (1775–1783), slaves had been institutionalized as a racial caste. The caste associated with African ancestry. When the United States Constitution was ratified in 1789, a small number of free people of color were able to vote. This was because they were men who owned property. During and shortly after the Revolutionary War, abolitionist laws were passed in most Northern states, and there was a movement created to end slavery. Slave states tried to extend slavery into new Western territories. They wanted to do this to keep their share of political power in the country. Southern leaders also wanted to annex Cuba as a slave territory. The United States became split over the issue of slavery. It was split into slave and free states. The Mason–Dixon line divided the country. The line divided (free) Pennsylvania from (slave) Maryland.
While Jefferson was president, Congress prohibited the importation of slaves, effective 1808. Although smuggling (illegal importing) through Spanish Florida was common. Slave trading within the United States, however, continued at a fast pace. This was because there was a need for labor due to the creation of cotton plantations in the Deep South. New communities of African-American culture were created in the Deep South. There were 4 million slaves in the Deep South before they were set free.