Chang Yŏngsil

Chang Yŏngsil was a smart maker in Korea.

He was born into a low class. But a king saw his talent. The king gave him a job at the palace.

Chang made tools to study the sky. He made a globe to track stars.

This helped people know the time.

He also made a special clock. It used water to tell time. It even made sounds with a bell.

Chang made a clock for the sun too. It was shaped like a bowl.

People used it in the streets.

He even made a tool to measure rain.

His many inventions helped his land.

Chang Yŏngsil was a famous inventor in Korea. He lived during the Joseon dynasty. Chang was born into a low social class. However, King Sejong saw his great skill. The king gave him a job at the royal palace.

Chang built tools to study the stars. He made a celestial globe. This is a round model of the sky. It used a waterwheel to turn. This helped people track the sun and moon.

He also made a special water clock. It was called the Jagyeokru. It used falling water to tell time. It could even make sounds. It used bells and drums to tell people the hour.

Chang made a sun clock too. It was called an Angbu-ilgu. This bronze bowl used shadows to show time. He put these in busy streets. This helped many people know the time.

He also worked on tools for farmers. He helped make a rain gauge. This tool measured how much rain fell. These tools helped the country grow food.

Chang Yŏngsil was a brilliant inventor and scientist in Korea. He lived during the Joseon dynasty. He was born into a very low social class called nobi. This meant he was considered government property. Despite this, King Sejong saw his amazing talent for engineering. The king gave him a special job at the royal palace.

Chang worked hard to help his country through science. He made tools that helped people track time and the stars. He also made tools to help farmers manage water. His work helped the Joseon dynasty advance in technology.

One of his most famous inventions was the Jagyeokru. This was a self-striking water clock. It worked by using water that dripped from top jars to bottom jars. As water filled the lower container, it moved floating arrows. These arrows tilted boards filled with small iron balls. The balls rolled down pipes to hit larger balls. This caused a loud sound from a bell, gong, or drum.

This system told the public the time automatically. It was much better than older clocks that needed a person to watch them constantly.

Chang also built many tools to study the sky. He made an armillary sphere called a honcheonui in 1433. This device used a waterwheel to rotate a globe inside. It helped astronomers track the sun, moon, and stars. He also helped create the Angbu-ilgu. This was a bronze sundial shaped like a bowl. It used lines to show time and seasonal changes.

Because many people could not read, he added animal shapes to it. These shapes helped everyone understand the time easily.

Chang's life was full of important dates and places. He worked in the royal court in Hanseong, which is now Seoul. In 1434, he finished the self-striking water clock. By 1441, a rain gauge called the cheugugi was introduced. This tool was 42.5 cm tall and 17 cm wide. He also worked on the Gabinja printing press in 1434. This press used copper-zinc and lead-tin alloys. It was twice as fast as older presses.

These inventions helped make Korean science very strong.

Many of Chang's tools helped with everyday life. The rain gauge and water gauge helped farmers manage water for crops. This was very important because the economy relied on farming. His work with metal also helped improve Korean weapons. Even though he was a commoner, his skills changed the country. Some officials were jealous of his success. In 1442, a decorated chair he built for the king broke. Chang was punished and sent away from the palace. We do not know exactly when he died.

Chang Yŏngsil was a highly skilled mechanical engineer and scientist. He lived during the Joseon dynasty in Korea. His life is a remarkable story of talent overcoming social barriers. Chang was born as a nobi, which was the lowest social class. This meant he was considered government-owned property. His mother was a government-registered courtesan. His father was of Yuan dynasty descent. Despite this low status, his engineering brilliance caught the attention of King Sejong. The king gave him a position as a court technician in the royal palace at Hanseong, which is modern-day Seoul.

Chang's work focused on creating precise instruments for time and astronomy. One major task was building a celestial globe to measure astronomical objects. He studied instructions from Arabian and Chinese scholars. Although the early instructions were incomplete, Chang worked for two months to build a spherical device. In 1433, he successfully created an armillary sphere called a honcheonui. This device used a waterwheel to rotate an internal globe. This rotation allowed astronomers to track the positions of the sun, moon, and stars. Later versions, called gyupyo, could also account for seasonal variations in time. These instruments were used by astronomers near the Gyeonghoeru Pavilion in Gyeongbok Palace.

In 1434, Chang helped develop the Jagyeokru, a self-striking water clock. Before this, people used stacked water jars to tell time. However, someone had to watch the jars constantly to strike a drum every hour. Chang traveled to China to study automatic designs to solve this problem. The Jagyeokru used a complex system of water, levers, and pulleys. It featured four water containers and two receiving jars. Inside the lower container, twelve floating arrows acted as indicators. As water seeped down, an arrow would tilt a board filled with small iron balls. These balls rolled into a container of larger iron balls. The resulting collision sent the larger balls down a pipe to hit a giant cymbal. This automatic process announced the time with bells, gongs, and drums.

Chang also contributed to improvements in printing and timekeeping for the public. In 1434, scientists built the Gabinja printing press. This press used alloys of copper-zinc and lead-tin. It was twice as fast as previous presses and produced very clear Chinese characters. To provide a cheaper way to tell time, Chang and other scientists created the Angbu-ilgu. This was a bronze, pot-shaped sundial. It featured 13 meters to indicate time and seven curved lines to compensate for seasonal sun movements. To help commoners who could not read, Chang engraved twelve Chinese zodiac shapes on the device. These sundials were placed in busy areas so everyone could see the time.

Agriculture was the foundation of the Joseon economy. This made water management a vital scientific goal. In 1441, a standardized rain gauge called the cheugugi was introduced. These gauges were 42.5 cm high and 17 cm in diameter. They helped gather precipitation data from different regions. Chang also invented the Supyo, which was the world's first water gauge. This was a calibrated stone column placed in a body of water. It was connected to a stone bridge to help farmers monitor water levels. These tools allowed for much better management of crops during droughts.

Chang's expertise also extended to metallurgy and weaponry. King Sejong noticed that Korean melee weapons were sometimes heavier or duller than those of neighbors. He sent Chang to Gyeongsang Province to investigate. Because Chang had experience as a gwanno, or a man-slave in government employ, he knew much about metalworking. He surveyed available metals and their specific characteristics. He then presented this research to the king and military generals. This work helped improve the development of Korean weaponry. His ability to analyze the physical properties of metals was a key part of his scientific success.

Despite his many successes, Chang's career ended abruptly due to political jealousy. Some government officials were unhappy that a person of low origin achieved such fame. In 1442, King Sejong ordered Chang to build a gama, which was a decorated sedan chair. The chair broke while the king was traveling. Chang was held responsible for the failure. Although the king did not want this, Chang was jailed, flogged 80 times, and expelled from the palace. The historical records do not state exactly when or how he died. Some believe he died from the flogging, while others speculate he may have defected to China.