During a time before there were clocks, a slave boy named Jang Youngsil was born.
Even though Youngsil was a slave, he was very talented and bright.
He could fix anything, and even better, he made fantastic inventions.
By the time he was ten years old, so many people had heard of his talent that the government office of Busan decided to hire him.
One summer there was a terrible drought in Busan.
Youngsil thought to himself, "If only there was a way to get water from the mountains to the fields!"
Suddenly, he had an idea. That was it!
He could make a long pipe that would direct the water from the mountain streams to the farms!
Everyone was amazed. Youngsil had invented an irrigation pipe.
King Sejong heard of Youngsil's amazing pipe.
"This boy must be a genius!" the king thought.
"I must meet him!" King Sejong summoned Youngsil to court.
When the king met Youngsil, he saw great potential.
"But first he must learn more," the king said to himself.
The king asked the great astrologer Yoon Saung to be Youngsil's mentor.
When the king saw that Youngsil was a quick learner, he sent him to China to study astrology.
Youngsil studied how the Chinese built water clocks, astrolabes, and sundials.
He was amazed at the advances in science that the Chinese had made.
"I must use what I have learned here to help advance Korean science," Youngsil thought.
When Youngsil returned from China, the king told his state ministers that he wished to give Youngsil a government position.
The ministers protested and cried out, "But Your Majesty, a slave cannot take a government position!"
Hwang Hui, the minister of culture and education, stepped forward and said, "Talent is more important than social status.
Youngsil deserves this honor!"
The ministers saw the truth in Hwang Hui's statement.
In 1423, Youngsil became a government official.
Youngsil vowed to use this honor to help his people and his king.
He decided to make a clock.
A clock would help farmers know when to plant crops.
A clock would make daily life more organized.
Youngsil modeled his clock on Chinese water clocks and presented it to King Sejong.
After the king saw Youngsil's marvelous water clock, he commissioned Youngsil to invent an astrolabe.
A great invention often requires teamwork.
So, fellow government official Yi Chun worked with Youngsil on the astrolabe.
After careful research,
they constructed a sphere that enabled a person to measure the angle between a planet or star and the point directly over that person's head.
By measuring that angle, scientists could find out precisely where they were located in relation to the rest of the universe.
Youngsil was very happy.
Now people could tell time and study the stars and solar system.
However, he was not satisfied with his water clock.
"How could I create a clock that would tell time automatically?" he wondered.
Youngsil studied automatic clocks invented in China and Arabia.
After careful research he created an automatic water clock in 1434.
The clock worked by letting water drip from a large container into a small container.
When the small container was full, it pushed a small marble into a big marble, which then caused a bell to ring.
The king was so pleased with this automatic water clock that he promoted Youngsil to an even higher government position.
This was a great honor, indeed!
When Youngsil saw the farmers working hard to feed everyone, he decided to invent a device that would predict floods and droughts.
A jar filled with rainwater gave him a brilliant idea.
He would make a container that would collect the rain and then measure how much had fallen!
Thus, in 1441, Youngsil invented the world's first rain gauge.
Youngsil was proud of everything he had invented.
But he knew that his success was because the king had given him a government position.
So, he decided to thank the king by making him a carriage.
When King Sejong rode in Youngsil's carriage, however, it broke!
Youngsil was sent to prison for making a poorly built carriage and was never heard from again.
Some say the king, who believed in Youngsil, secretly released him.
Some say that Youngsil used his genius to escape.
Others say he died in prison. No one will ever know what became of Youngsil.
Yet we know what became of his inventions.
They contributed greatly to Korean science.
Even today, the Jang Youngsil science award rewards talented Korean scientists.
Youngsil's many inventions changed the lives of Koreans.
Thanks to him, Koreans could farm well and tell time.
He was born a slave at a time when status was more important than talent.
But Jang Youngsil showed that talent is more important than status.
He is proof that hard work can lead to great success.