29 Jang Young-sil

Jang Young-sil (장영실)

Time period:

14th century

Subject:

Mechanical engineering

Biography:

Jang Young-sil was a Korean mechanical engineer, scientist, and inventor during the reign of Sejong the Great in the Joseon dynasty. He was born in 1390, as a “천민 – Cheonmin”, the lowest caste of commoners, because his mother was a “기생 – Kisaeng”, women that were enslaved to be trained as courtesans. Even from a young age, Jang was famous in his hometown for his innate talent in craftsmanship. He was excellent at refining metals, reinforcing castle walls, as well as repairing farming tools and weapons. At one point, a drought had struck his hometown, endangering the crops and the people. Jang decided to dig out waterways and use his invention (similar to a water pump) to bring in water from a remote source to solve the issue. This event was reported to Sejong the Great, who single-handedly lead the scientific golden age of Joseon, due to his policy of meritocracy, as opposed to traditional caste systems. Sejong the Great invited Jang and other talented scientists to his new science program, the “집현전 – Jiphyeonjeon”, also known as the “Hall of Worthies”, where Jang invented various contraptions and devices to further progress science in Joseon, and to improve the lives of the common people.

Summary of their contributions:

Jang invented and developed a variety of instruments during his time at the Jiphyeonjeon.

His inventions include:

1. 간의 (gan-eui), 혼천의 (hon-cheon-eui): Astronomical instruments used to measure various information of different celestial bodies, including its location, time, longitudes and lattitudes. Jang first invented the 간의, then further improved it to develop the 혼천의. This was significant as most of the astronomical instruments were imported from Arabian or Chinese scholars, but these were often incomplete due to its capabilities of developing weaponry.

2. 자격루 (jaa-gyeok-roo): Timed clocks that made use of flowing water. This was connected to a large bell, drum, or gong that indicated the time of day, with a small doll that appeared, holding a chart of the current time.

3. 갑인자 (gaap-in-jaa): Iron printing press that was developed using copper-zinc, and lead-tin alloys. It was said to be able to print Chinese characters twice as fast as the previous printing presses, effectively and efficiently.

4. Various sundials: Jang developed a variety of sundials, which were widely distributed around the country, allowing everyone to be able to tell the time accurately. Some of the sundials were designed to be portable and were carried by important government officials.

5. 규포 (gyu-pyo): A device that accuratley measured the length of a year using the shadow from a rod cast by the sun.

6. 일성정시의 (il-seong-jeong-si-eui): A device that combined the features of the sundial and the stardial to accurately measure the time of the day and night. It was sometimes used in order to strengthen the security and maintain vigilant guard patrols.

7. 수표 (soo-pyo), 측우기 (cheuk-woo-gi): Devices that measured the amount of rainfall. The 수표 measured the water levels around various streams of water, while the 측우기 measured water using a portable device, which allowed for accurate measurements and records of rainfall around various locations across the country, which greatly helped in identifying the weather patterns and supported agriculture.

Jang also conducted lots of research for Sejong the Great, including research in weaponry using his prior knowledge of metal alloys, which contributed in the creation of sharper weapons for the army.

Integration with the BC Secondary Science Curriculum:

Subjects

Science 8: Space Exploration and Earth Science

Science 9: Earth and Space Science and the Solar System

Curricular Competencies

1. Make observations aimed at identifying their own questions, including increasingly complex ones, about the natural world
2. Collaboratively and individually plan, select, and use appropriate investigation methods, including field work and lab experiments, to collect reliable data (qualitative and quantitative)
3. Describe specific ways to improve their investigation methods and the quality of the data
4. Consider the changes in knowledge over time as tools and technologies have developed
5. Contribute to care for self, others, community, and world through individual or collaborative approaches
6. Generate and introduce new or refined ideas when problem solving
7. Contribute to finding solutions to problems at a local and/or global level through inquiry

First People’s Principles of Learning

Learning ultimately supports the well-being of the self, the family, the community, the land, the spirits, and the ancestors.

References:

Nam, MH. (2014). Yeong-sil Jang (Unknown). In: Ceccarelli, M. (eds) Distinguished Figures in Mechanism and Machine Science. History of Mechanism and Machine Science, vol 26. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-8947-9_6

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