{"content_id":"nbazrmia6u","slug":"jang-yeong-sil-jagyeongnu-making-and-automatic-time-signals","locale":"en","schema_type":"Article","category":"knowledge_base","category_name":"Knowledge Base","title":"Jagyeongnu by Jang Yeong-sil: Construction and Time Signals","summary":"The Jagyeongnu, built by Jang Yeong-sil and others, converted the flow of water into mechanical signals to announce the time automatically. Its recorded completion in 1433, the start of its use in 1434, and the surviving artifact made in 1536 must be distinguished.","sponsorship_disclosure":null,"affiliate_disclosure":null,"commerce_disclosure":null,"author":{"name":"Injoys Editorial Team","url":"https://injoys.com/ko/about"},"key_points":["The Jagyeongnu used a mechanical device to do the work of people who read a water clock's markings and announced the time.","In 1433, credit for building the Jagyeokgungnu was recorded, and a new water clock came into use on the first day of the seventh lunar month in 1434.","The movement of a rod floating in water passed through balls and levers to trigger time signals from a bell, drum, and gong.","In 1437, a method was adopted to relay signals from the palace Jagyeongnu to the Uigeumbu.","The surviving water-clock apparatus of the Changgyeonggung Palace Jagyeongnu is part of an improved version made in 1536; Jang Yeong-sil's original mechanism has not survived."],"content_markdown":"Jang Yeong-sil and others completed the Jagyeongnu in 1433. Its automatic time signals solved the problem of having someone watch a water clock and announce the time. The device, used from July 1434, is remembered for changing how Joseon kept time.\n\nThis article follows the records in the National Institute of Korean History’s *Annals of King Sejong*, checked in October 2026.\n\n## What problem was the Jagyeongnu built to solve?\n\nThe Jagyeongnu was designed to remove the need for a person to read and announce the time. In earlier water clocks, a marked rod rose as the water level climbed. An attendant had to watch its markings and announce the time.\n\nA time signal announces a set time through a sound or display. Even if the water clock measured time, the signal would be wrong if the attendant misread it. The *Annals of King Sejong* records that Sejong was concerned about mistakes by the attendants responsible for time signals. The Jagyeongnu had a mechanism with wooden figures to do that work instead. [*Annals of King Sejong*, 1st day of the 7th month of Sejong’s 16th year](https://sillok.history.go.kr/id/kda_11607001_004)\n\n| Category | Earlier water clock watched by a person | Jagyeongnu |\n|---|---|---|\n| Measuring time | Used the flow of water and markings on a rod | Used the flow of water and the rod’s movement |\n| Determining the time | An attendant read the markings | A mechanism operated when the rod reached a set height |\n| Announcing the time | An attendant gave the signal | Figures struck a bell, drum and gong |\n| Work still requiring an attendant | Maintaining the water clock and giving time signals | Changing the water and maintaining the mechanism |\n\n## How a technician born a government slave gained an official post\n\nJang Yeong-sil’s appointment to an official post faced opposition because of his social status. He is known as an early Joseon technician who was born a government slave in Dongnae County. A government slave was a male slave attached to a government office. His birth and death years are unknown.\n\nAn entry in the 1433 annals recounts an earlier discussion about appointing him to the Royal Wardrobe Office. Heo Jo opposed it because of his mother’s status. Jo Mal-saeng argued that Jang Yeong-sil was suited to the office. Sejong later accepted his ministers’ views and appointed him to a *byeoljwa* post.\n\nMaking the Jagyeokgungnu was the turning point at which his technical work led to a higher post. Citing his contribution to its construction, Sejong proposed giving him the additional post of *hogun*. The ministers agreed, and Sejong followed their view.\n\n\u003e He has made an instrument that will be passed down for a long time, so his contribution is considerable. I wish to give him the additional post of hogun.\n\nSejong, *Annals of King Sejong*, 16th day of the 9th month of Sejong’s 15th year. [The entry](https://sillok.history.go.kr/id/kda_11509016_003)\n\n## A timeline distinguishing construction from use\n\nSeparate records confirm the Jagyeongnu’s completion and the start of its use. Our History Net’s account of the Jagyeongnu gives 1433 as its completion year. The annals state that the new water clock came into use on the **1st day of the 7th lunar month of 1434**. The months and days below follow the lunar dates recorded at the time.\n\n| Date | Recorded event | Source |\n|---|---|---|\n| 16th day of the 9th month of 1433 | Discussion of the contribution made by building the Jagyeokgungnu and granting the post of hogun | Relevant entry in the *Annals of King Sejong*, Sejong’s 15th year |\n| 1st day of the 7th month of 1434 | Start of use of the new water clock and description of its automatic time-signal mechanism | Relevant entry in the *Annals of King Sejong*, Sejong’s 16th year |\n| 28th day of the 6th month of 1437 | Order to relay time signals from the palace to Uigeumbu | Relevant entry in the *Annals of King Sejong*, Sejong’s 19th year |\n| 1438 | Construction of the Okru, which also displayed changes in the heavens | Our History Net, “Astronomical Instruments and Calendrical Systems under Sejong” |\n| 3rd month of 1442 | Investigation after a royal palanquin built under his supervision broke | Our History Net, “Jang Yeong-sil” |\n| 1536 | Installation of an additional Jagyeongnu at Changgyeonggung Palace | National Palace Museum of Korea collection description |\n\nThe 1433 entry confirms his contribution to the construction. It alone cannot establish the completion date or testing schedule. The 1434 entry gives specific details about the start of use and the device’s construction. [Our History Net, “Jagyeongnu”](https://contents.history.go.kr/mobile/kc/view.do?code=kc_age_30\u0026levelId=kc_r300785)\n\n## How the Jagyeongnu worked\n\nThe Jagyeongnu turned a rising water level into the movement of balls to announce the time. The water-clock section measured the passage of time. The time-signal mechanism turned that movement into sounds and displays by figures.\n\n### Vessels that supplied and received water\n\nThe *pasuho* were vessels that released water, and the *susuho* were vessels that received it. The 1434 annals record four pasuho and two susuho. The susuho were used alternately when the water was changed. As the water level rose in a receiving vessel, a rod inside it rose too.\n\n### The sequence from rod to ball\n\nWhen the rod reached a set height, it activated a mechanism that released a ball. A small copper ball acted on a mechanism that released a larger iron ball. The force of the falling ball moved the figures that gave the time signals.\n\n1. Water flows from a pasuho into a susuho.\n2. As the water rises, the rod inside the susuho rises.\n3. At a set position, the rod activates the mechanism that releases a small ball.\n4. The small ball moves a lever mechanism, releasing a large iron ball.\n5. The iron ball’s movement sets the figures’ time-signal actions in motion.\n\n### What did the bell, drum and gong announce?\n\nThe bell, drum and gong announced different divisions of time. The bell marked the hour, the drum marked a night watch, and the gong marked a subdivision of a watch. Figures holding plaques showing the time also appeared in turn.\n\n| Display mechanism | What it announced |\n|---|---|\n| Figure striking the bell | An hour as a division of the day |\n| Figure striking the drum | A watch as a division of the night |\n| Figure striking the gong | A further division of a watch |\n| Figure holding a time plaque | A display of the corresponding time |\n\nNighttime signals also needed seasonal adjustment. The annals describe a structure in which copper plates were changed according to the seasonal divisions. Automatic time signals did not eliminate the need to change the water or make seasonal adjustments. [Description of the water clock’s structure in the *Annals of King Sejong*](https://sillok.history.go.kr/id/kda_11607001_004)\n\n## How were palace time signals relayed through the capital?\n\nIn 1437, a method was adopted for relaying signals from the palace Jagyeongnu to Uigeumbu. The State Council raised the inaccuracy of the existing water clocks as a problem. It also identified attendants’ mistakes as a cause of incorrect entry and exit times.\n\nThe State Council asked for metal percussion instruments and drums to be placed at intermediate points to relay the signals. The plan was to hear the palace Jagyeongnu and give signals in sequence. Sejong accepted the proposal. [*Annals of King Sejong*, 28th day of the 6th month of Sejong’s 19th year](https://sillok.history.go.kr/id/wda_11906028_003)\n\n| Stage | Role | What the record indicates |\n|---|---|---|\n| Palace Jagyeongnu | Produce the reference time signal | Establish the time at the starting point |\n| Intermediate relay points | Hear the sound and give the next signal | Carry the signal beyond the palace |\n| Relay to Uigeumbu | Connect the signal to time announcements in the capital | Enable multiple places to follow the same reference |\n\nThis record helps define the extent of the automation. In the palace, a machine announced the time. Outside the palace, people heard the sound and relayed the signal. Describing this as a system for sharing a common time is an interpretation based on the record.\n\n## Jang Yeong-sil’s work and the scope of the joint effort\n\nJang Yeong-sil’s work included making water clocks and astronomical observation instruments. Our History Net also describes his study of astronomical instruments in Ming China. That account must be considered alongside the later record *Yeollyeosil Gisul*.\n\nResearch into written sources and technical work were divided among those making the instruments. For the *ganui*, Jeong Cho, Jeong In-ji and others studied its design. Jang Yeong-sil and Yi Cheon supervised the technicians. His work also included taking part in casting the Gapinja type and supervising mineral production. [Our History Net, “Jang Yeong-sil”](https://contents.history.go.kr/mobile/kc/view.do?levelId=kc_n310300)\n\n| Instrument | Main function | Relationship to the Jagyeongnu |\n|---|---|---|\n| Ganui | Observing the positions of celestial bodies | Related to aligning clock times with observation results |\n| Honcheonui | Determining the positions and movements of celestial bodies | Part of the astronomical observation effort |\n| Angbuilgu | Determining the time and seasonal divisions from the sun’s shadow | A sundial that uses sunlight |\n| Jagyeongnu | Automatically announcing the time measured by the flow of water | A water clock installed at Borugak |\n| Okru | Displaying the time and changes in the heavens | An astronomical clock installed at Heumgyeonggak in 1438 |\n\nThe Angbuilgu was an instrument whose concave surface showed a shadow to be read. The Jagyeongnu could measure time even at night, without sunlight. The Okru added a mechanism showing changes in the heavens. These instruments served observation and timekeeping in different ways. [Our History Net, “Astronomical Instruments and Calendrical Systems under Sejong”](https://contents.history.go.kr/mobile/tt/view.do?levelId=tt_b21)\n\n## From what period are the surviving water vessels?\n\nThe surviving vessels of the Changgyeonggung Palace Jagyeongnu are **part of an instrument made in 1536**. The Jagyeongnu made by Jang Yeong-sil under Sejong has not survived. The National Palace Museum of Korea describes the surviving objects as three pasuho and two susuho.\n\n| Category | Jagyeongnu under Sejong | Surviving vessels of the Changgyeonggung Palace Jagyeongnu |\n|---|---|---|\n| Date | Completed in 1433, brought into use in 1434 | Additionally installed at Changgyeonggung Palace in 1536 |\n| Nature | Automatic water clock made by Jang Yeong-sil and others | Part of an improved version that followed Sejong’s instrument |\n| Water vessels | Records list four pasuho and two susuho | Three pasuho and two susuho survive |\n| Preservation | Original instrument has not survived | Water vessels survive |\n\nThe remaining vessels alone cannot show the full automatic time-signal mechanism. The susuho bear inscriptions naming the participants in their construction and their posts. The inscription on the large pasuho provides evidence for the construction date. The surviving objects are confirmed as part of the National Palace Museum of Korea’s collection. [National Palace Museum of Korea collection description](https://www.gogung.go.kr/gogung/pgm/psgudMng/view.do?menuNo=800065\u0026psgudSn=370348)\n\n## Records and interpretation\n\nFacts recorded directly must be distinguished from later accounts. The annals are the key source confirming Jang Yeong-sil’s contribution to making the Jagyeongnu and the start of its use. His childhood and later years are not known to the same degree.\n\n### Facts confirmed by records\n\nThe 1433 annals state that Sejong recognized Jang Yeong-sil’s contribution to the construction. The 1434 entry describes the structure of the new water clock. The 1437 entry records the adoption of a method for relaying time signals.\n\n### Meaning shared by the explanatory accounts\n\nOur History Net explains that automatic time signals reduced the attendants’ workload. This interprets the mechanism as connecting time measurement and announcement. It should not, however, be taken to mean that the device was entirely free of error.\n\n### Conflicting or unconfirmed details\n\nThe annals and the *Asan Jang Clan Genealogy* give different accounts of his family background. They disagree on when his ancestors came from China to settle in Korea and on their lineage. The exact date of his appointment to the *byeoljwa* post at the Royal Wardrobe Office is also difficult to establish.\n\nPunishment and dismissal followed the 1442 palanquin accident. His subsequent activities and the date of his death are unknown. Neither a year of death nor a place of retirement can be established from this. Stories about his childhood and scenes in dramas must also be distinguished from historical sources. [Our History Net’s review of his life and the records](https://contents.history.go.kr/mobile/kc/view.do?levelId=kc_n310300)\n\n## Why automatic time signals matter today\n\nThe Jagyeongnu is an example of a machine that conveyed measured information at the moment it was needed. It converted the continuous change in water level into signals at set times. Those signals were conveyed by sound and displays by figures.\n\nWhat can be compared with automation today is the connection between functions. The breakdown below is a modern way to analyze the device. It does not mean the technology was the same as electronics or computers.\n\n- Measurement: The flow of water and the height of the rod indicated elapsed time.\n- Activation: At a set position, a ball was released to move the next mechanism.\n- Announcement: A bell, drum, gong and time plaque announced the time.\n- Operation: The water had to be changed, and seasonal adjustments were needed.\n\n## Frequently asked questions\n\n### Was the Jagyeongnu made in 1433 or 1434?\n\nOur History Net gives 1433 as the year of completion. That year’s annals also mention the contribution made by building the Jagyeokgungnu. The new water clock came into use on the 1st day of the 7th lunar month of 1434.\n\n### Did automatic time signals eliminate the need for people?\n\nThe main task automated was determining and announcing the time. The annals say the susuho were used alternately when the water was changed. Maintenance also included changing parts to suit the seasonal divisions.\n\n### Are the Jagyeongnu and Borugak the same thing?\n\nThe Jagyeongnu was a water clock, while Borugak was the building where it was installed. Under Sejong, the Jagyeongnu operated at Borugak, south of Gyeonghoeru Pavilion in Gyeongbokgung Palace. For this reason, it was also called the Borugakru.\n\n### Did Jang Yeong-sil make the museum’s water vessels himself?\n\nThe surviving vessels are not the originals made by Jang Yeong-sil. They are part of the Jagyeongnu installed at Changgyeonggung Palace in 1536. Nor has the entire automatic time-signal mechanism from Sejong’s reign survived.\n\n### Did Jang Yeong-sil die in 1442?\n\nThe year 1442 appears in accounts of the palanquin accident and his punishment. The incident cannot be treated as a record of his death. His year of death is unknown.","content_html":"\u003cp\u003eJang Yeong-sil and others completed the Jagyeongnu in 1433. Its automatic time signals solved the problem of having someone watch a water clock and announce the time. The device, used from July 1434, is remembered for changing how Joseon kept time.\u003c/p\u003e\n\u003cp\u003eThis article follows the records in the National Institute of Korean History’s \u003cem\u003eAnnals of King Sejong\u003c/em\u003e, checked in October 2026.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#what-problem-was-the-jagyeongnu-built-to-solve\" class=\"anchor\" id=\"what-problem-was-the-jagyeongnu-built-to-solve\"\u003e\u003c/a\u003eWhat problem was the Jagyeongnu built to solve?\u003c/h2\u003e\n\u003cp\u003eThe Jagyeongnu was designed to remove the need for a person to read and announce the time. In earlier water clocks, a marked rod rose as the water level climbed. An attendant had to watch its markings and announce the time.\u003c/p\u003e\n\u003cp\u003eA time signal announces a set time through a sound or display. Even if the water clock measured time, the signal would be wrong if the attendant misread it. The \u003cem\u003eAnnals of King Sejong\u003c/em\u003e records that Sejong was concerned about mistakes by the attendants responsible for time signals. The Jagyeongnu had a mechanism with wooden figures to do that work instead. \u003ca href=\"https://sillok.history.go.kr/id/kda_11607001_004\"\u003e\u003cem\u003eAnnals of King Sejong\u003c/em\u003e, 1st day of the 7th month of Sejong’s 16th year\u003c/a\u003e\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eCategory\u003c/th\u003e\n\u003cth\u003eEarlier water clock watched by a person\u003c/th\u003e\n\u003cth\u003eJagyeongnu\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003eMeasuring time\u003c/td\u003e\n\u003ctd data-label=\"Earlier water clock watched by a person\"\u003eUsed the flow of water and markings on a rod\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu\"\u003eUsed the flow of water and the rod’s movement\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003eDetermining the time\u003c/td\u003e\n\u003ctd data-label=\"Earlier water clock watched by a person\"\u003eAn attendant read the markings\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu\"\u003eA mechanism operated when the rod reached a set height\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003eAnnouncing the time\u003c/td\u003e\n\u003ctd data-label=\"Earlier water clock watched by a person\"\u003eAn attendant gave the signal\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu\"\u003eFigures struck a bell, drum and gong\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003eWork still requiring an attendant\u003c/td\u003e\n\u003ctd data-label=\"Earlier water clock watched by a person\"\u003eMaintaining the water clock and giving time signals\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu\"\u003eChanging the water and maintaining the mechanism\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003ch2\u003e\n\u003ca href=\"#how-a-technician-born-a-government-slave-gained-an-official-post\" class=\"anchor\" id=\"how-a-technician-born-a-government-slave-gained-an-official-post\"\u003e\u003c/a\u003eHow a technician born a government slave gained an official post\u003c/h2\u003e\n\u003cp\u003eJang Yeong-sil’s appointment to an official post faced opposition because of his social status. He is known as an early Joseon technician who was born a government slave in Dongnae County. A government slave was a male slave attached to a government office. His birth and death years are unknown.\u003c/p\u003e\n\u003cp\u003eAn entry in the 1433 annals recounts an earlier discussion about appointing him to the Royal Wardrobe Office. Heo Jo opposed it because of his mother’s status. Jo Mal-saeng argued that Jang Yeong-sil was suited to the office. Sejong later accepted his ministers’ views and appointed him to a \u003cem\u003ebyeoljwa\u003c/em\u003e post.\u003c/p\u003e\n\u003cp\u003eMaking the Jagyeokgungnu was the turning point at which his technical work led to a higher post. Citing his contribution to its construction, Sejong proposed giving him the additional post of \u003cem\u003ehogun\u003c/em\u003e. The ministers agreed, and Sejong followed their view.\u003c/p\u003e\n\u003cblockquote\u003e\n\u003cp\u003eHe has made an instrument that will be passed down for a long time, so his contribution is considerable. I wish to give him the additional post of hogun.\u003c/p\u003e\n\u003c/blockquote\u003e\n\u003cp\u003eSejong, \u003cem\u003eAnnals of King Sejong\u003c/em\u003e, 16th day of the 9th month of Sejong’s 15th year. \u003ca href=\"https://sillok.history.go.kr/id/kda_11509016_003\"\u003eThe entry\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#a-timeline-distinguishing-construction-from-use\" class=\"anchor\" id=\"a-timeline-distinguishing-construction-from-use\"\u003e\u003c/a\u003eA timeline distinguishing construction from use\u003c/h2\u003e\n\u003cp\u003eSeparate records confirm the Jagyeongnu’s completion and the start of its use. Our History Net’s account of the Jagyeongnu gives 1433 as its completion year. The annals state that the new water clock came into use on the \u003cstrong\u003e1st day of the 7th lunar month of 1434\u003c/strong\u003e. The months and days below follow the lunar dates recorded at the time.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eDate\u003c/th\u003e\n\u003cth\u003eRecorded event\u003c/th\u003e\n\u003cth\u003eSource\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Date\"\u003e16th day of the 9th month of 1433\u003c/td\u003e\n\u003ctd data-label=\"Recorded event\"\u003eDiscussion of the contribution made by building the Jagyeokgungnu and granting the post of hogun\u003c/td\u003e\n\u003ctd data-label=\"Source\"\u003eRelevant entry in the \u003cem\u003eAnnals of King Sejong\u003c/em\u003e, Sejong’s 15th year\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Date\"\u003e1st day of the 7th month of 1434\u003c/td\u003e\n\u003ctd data-label=\"Recorded event\"\u003eStart of use of the new water clock and description of its automatic time-signal mechanism\u003c/td\u003e\n\u003ctd data-label=\"Source\"\u003eRelevant entry in the \u003cem\u003eAnnals of King Sejong\u003c/em\u003e, Sejong’s 16th year\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Date\"\u003e28th day of the 6th month of 1437\u003c/td\u003e\n\u003ctd data-label=\"Recorded event\"\u003eOrder to relay time signals from the palace to Uigeumbu\u003c/td\u003e\n\u003ctd data-label=\"Source\"\u003eRelevant entry in the \u003cem\u003eAnnals of King Sejong\u003c/em\u003e, Sejong’s 19th year\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Date\"\u003e1438\u003c/td\u003e\n\u003ctd data-label=\"Recorded event\"\u003eConstruction of the Okru, which also displayed changes in the heavens\u003c/td\u003e\n\u003ctd data-label=\"Source\"\u003eOur History Net, “Astronomical Instruments and Calendrical Systems under Sejong”\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Date\"\u003e3rd month of 1442\u003c/td\u003e\n\u003ctd data-label=\"Recorded event\"\u003eInvestigation after a royal palanquin built under his supervision broke\u003c/td\u003e\n\u003ctd data-label=\"Source\"\u003eOur History Net, “Jang Yeong-sil”\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Date\"\u003e1536\u003c/td\u003e\n\u003ctd data-label=\"Recorded event\"\u003eInstallation of an additional Jagyeongnu at Changgyeonggung Palace\u003c/td\u003e\n\u003ctd data-label=\"Source\"\u003eNational Palace Museum of Korea collection description\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe 1433 entry confirms his contribution to the construction. It alone cannot establish the completion date or testing schedule. The 1434 entry gives specific details about the start of use and the device’s construction. \u003ca href=\"https://contents.history.go.kr/mobile/kc/view.do?code=kc_age_30\u0026amp;levelId=kc_r300785\"\u003eOur History Net, “Jagyeongnu”\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#how-the-jagyeongnu-worked\" class=\"anchor\" id=\"how-the-jagyeongnu-worked\"\u003e\u003c/a\u003eHow the Jagyeongnu worked\u003c/h2\u003e\n\u003cp\u003eThe Jagyeongnu turned a rising water level into the movement of balls to announce the time. The water-clock section measured the passage of time. The time-signal mechanism turned that movement into sounds and displays by figures.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#vessels-that-supplied-and-received-water\" class=\"anchor\" id=\"vessels-that-supplied-and-received-water\"\u003e\u003c/a\u003eVessels that supplied and received water\u003c/h3\u003e\n\u003cp\u003eThe \u003cem\u003epasuho\u003c/em\u003e were vessels that released water, and the \u003cem\u003esusuho\u003c/em\u003e were vessels that received it. The 1434 annals record four pasuho and two susuho. The susuho were used alternately when the water was changed. As the water level rose in a receiving vessel, a rod inside it rose too.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#the-sequence-from-rod-to-ball\" class=\"anchor\" id=\"the-sequence-from-rod-to-ball\"\u003e\u003c/a\u003eThe sequence from rod to ball\u003c/h3\u003e\n\u003cp\u003eWhen the rod reached a set height, it activated a mechanism that released a ball. A small copper ball acted on a mechanism that released a larger iron ball. The force of the falling ball moved the figures that gave the time signals.\u003c/p\u003e\n\u003col\u003e\n\u003cli\u003eWater flows from a pasuho into a susuho.\u003c/li\u003e\n\u003cli\u003eAs the water rises, the rod inside the susuho rises.\u003c/li\u003e\n\u003cli\u003eAt a set position, the rod activates the mechanism that releases a small ball.\u003c/li\u003e\n\u003cli\u003eThe small ball moves a lever mechanism, releasing a large iron ball.\u003c/li\u003e\n\u003cli\u003eThe iron ball’s movement sets the figures’ time-signal actions in motion.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch3\u003e\n\u003ca href=\"#what-did-the-bell-drum-and-gong-announce\" class=\"anchor\" id=\"what-did-the-bell-drum-and-gong-announce\"\u003e\u003c/a\u003eWhat did the bell, drum and gong announce?\u003c/h3\u003e\n\u003cp\u003eThe bell, drum and gong announced different divisions of time. The bell marked the hour, the drum marked a night watch, and the gong marked a subdivision of a watch. Figures holding plaques showing the time also appeared in turn.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eDisplay mechanism\u003c/th\u003e\n\u003cth\u003eWhat it announced\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Display mechanism\"\u003eFigure striking the bell\u003c/td\u003e\n\u003ctd data-label=\"What it announced\"\u003eAn hour as a division of the day\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Display mechanism\"\u003eFigure striking the drum\u003c/td\u003e\n\u003ctd data-label=\"What it announced\"\u003eA watch as a division of the night\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Display mechanism\"\u003eFigure striking the gong\u003c/td\u003e\n\u003ctd data-label=\"What it announced\"\u003eA further division of a watch\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Display mechanism\"\u003eFigure holding a time plaque\u003c/td\u003e\n\u003ctd data-label=\"What it announced\"\u003eA display of the corresponding time\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eNighttime signals also needed seasonal adjustment. The annals describe a structure in which copper plates were changed according to the seasonal divisions. Automatic time signals did not eliminate the need to change the water or make seasonal adjustments. \u003ca href=\"https://sillok.history.go.kr/id/kda_11607001_004\"\u003eDescription of the water clock’s structure in the \u003cem\u003eAnnals of King Sejong\u003c/em\u003e\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#how-were-palace-time-signals-relayed-through-the-capital\" class=\"anchor\" id=\"how-were-palace-time-signals-relayed-through-the-capital\"\u003e\u003c/a\u003eHow were palace time signals relayed through the capital?\u003c/h2\u003e\n\u003cp\u003eIn 1437, a method was adopted for relaying signals from the palace Jagyeongnu to Uigeumbu. The State Council raised the inaccuracy of the existing water clocks as a problem. It also identified attendants’ mistakes as a cause of incorrect entry and exit times.\u003c/p\u003e\n\u003cp\u003eThe State Council asked for metal percussion instruments and drums to be placed at intermediate points to relay the signals. The plan was to hear the palace Jagyeongnu and give signals in sequence. Sejong accepted the proposal. \u003ca href=\"https://sillok.history.go.kr/id/wda_11906028_003\"\u003e\u003cem\u003eAnnals of King Sejong\u003c/em\u003e, 28th day of the 6th month of Sejong’s 19th year\u003c/a\u003e\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eStage\u003c/th\u003e\n\u003cth\u003eRole\u003c/th\u003e\n\u003cth\u003eWhat the record indicates\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Stage\"\u003ePalace Jagyeongnu\u003c/td\u003e\n\u003ctd data-label=\"Role\"\u003eProduce the reference time signal\u003c/td\u003e\n\u003ctd data-label=\"What the record indicates\"\u003eEstablish the time at the starting point\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Stage\"\u003eIntermediate relay points\u003c/td\u003e\n\u003ctd data-label=\"Role\"\u003eHear the sound and give the next signal\u003c/td\u003e\n\u003ctd data-label=\"What the record indicates\"\u003eCarry the signal beyond the palace\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Stage\"\u003eRelay to Uigeumbu\u003c/td\u003e\n\u003ctd data-label=\"Role\"\u003eConnect the signal to time announcements in the capital\u003c/td\u003e\n\u003ctd data-label=\"What the record indicates\"\u003eEnable multiple places to follow the same reference\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThis record helps define the extent of the automation. In the palace, a machine announced the time. Outside the palace, people heard the sound and relayed the signal. Describing this as a system for sharing a common time is an interpretation based on the record.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#jang-yeong-sils-work-and-the-scope-of-the-joint-effort\" class=\"anchor\" id=\"jang-yeong-sils-work-and-the-scope-of-the-joint-effort\"\u003e\u003c/a\u003eJang Yeong-sil’s work and the scope of the joint effort\u003c/h2\u003e\n\u003cp\u003eJang Yeong-sil’s work included making water clocks and astronomical observation instruments. Our History Net also describes his study of astronomical instruments in Ming China. That account must be considered alongside the later record \u003cem\u003eYeollyeosil Gisul\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eResearch into written sources and technical work were divided among those making the instruments. For the \u003cem\u003eganui\u003c/em\u003e, Jeong Cho, Jeong In-ji and others studied its design. Jang Yeong-sil and Yi Cheon supervised the technicians. His work also included taking part in casting the Gapinja type and supervising mineral production. \u003ca href=\"https://contents.history.go.kr/mobile/kc/view.do?levelId=kc_n310300\"\u003eOur History Net, “Jang Yeong-sil”\u003c/a\u003e\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eInstrument\u003c/th\u003e\n\u003cth\u003eMain function\u003c/th\u003e\n\u003cth\u003eRelationship to the Jagyeongnu\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Instrument\"\u003eGanui\u003c/td\u003e\n\u003ctd data-label=\"Main function\"\u003eObserving the positions of celestial bodies\u003c/td\u003e\n\u003ctd data-label=\"Relationship to the Jagyeongnu\"\u003eRelated to aligning clock times with observation results\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Instrument\"\u003eHoncheonui\u003c/td\u003e\n\u003ctd data-label=\"Main function\"\u003eDetermining the positions and movements of celestial bodies\u003c/td\u003e\n\u003ctd data-label=\"Relationship to the Jagyeongnu\"\u003ePart of the astronomical observation effort\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Instrument\"\u003eAngbuilgu\u003c/td\u003e\n\u003ctd data-label=\"Main function\"\u003eDetermining the time and seasonal divisions from the sun’s shadow\u003c/td\u003e\n\u003ctd data-label=\"Relationship to the Jagyeongnu\"\u003eA sundial that uses sunlight\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Instrument\"\u003eJagyeongnu\u003c/td\u003e\n\u003ctd data-label=\"Main function\"\u003eAutomatically announcing the time measured by the flow of water\u003c/td\u003e\n\u003ctd data-label=\"Relationship to the Jagyeongnu\"\u003eA water clock installed at Borugak\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Instrument\"\u003eOkru\u003c/td\u003e\n\u003ctd data-label=\"Main function\"\u003eDisplaying the time and changes in the heavens\u003c/td\u003e\n\u003ctd data-label=\"Relationship to the Jagyeongnu\"\u003eAn astronomical clock installed at Heumgyeonggak in 1438\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe Angbuilgu was an instrument whose concave surface showed a shadow to be read. The Jagyeongnu could measure time even at night, without sunlight. The Okru added a mechanism showing changes in the heavens. These instruments served observation and timekeeping in different ways. \u003ca href=\"https://contents.history.go.kr/mobile/tt/view.do?levelId=tt_b21\"\u003eOur History Net, “Astronomical Instruments and Calendrical Systems under Sejong”\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#from-what-period-are-the-surviving-water-vessels\" class=\"anchor\" id=\"from-what-period-are-the-surviving-water-vessels\"\u003e\u003c/a\u003eFrom what period are the surviving water vessels?\u003c/h2\u003e\n\u003cp\u003eThe surviving vessels of the Changgyeonggung Palace Jagyeongnu are \u003cstrong\u003epart of an instrument made in 1536\u003c/strong\u003e. The Jagyeongnu made by Jang Yeong-sil under Sejong has not survived. The National Palace Museum of Korea describes the surviving objects as three pasuho and two susuho.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eCategory\u003c/th\u003e\n\u003cth\u003eJagyeongnu under Sejong\u003c/th\u003e\n\u003cth\u003eSurviving vessels of the Changgyeonggung Palace Jagyeongnu\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003eDate\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu under Sejong\"\u003eCompleted in 1433, brought into use in 1434\u003c/td\u003e\n\u003ctd data-label=\"Surviving vessels of the Changgyeonggung Palace Jagyeongnu\"\u003eAdditionally installed at Changgyeonggung Palace in 1536\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003eNature\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu under Sejong\"\u003eAutomatic water clock made by Jang Yeong-sil and others\u003c/td\u003e\n\u003ctd data-label=\"Surviving vessels of the Changgyeonggung Palace Jagyeongnu\"\u003ePart of an improved version that followed Sejong’s instrument\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003eWater vessels\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu under Sejong\"\u003eRecords list four pasuho and two susuho\u003c/td\u003e\n\u003ctd data-label=\"Surviving vessels of the Changgyeonggung Palace Jagyeongnu\"\u003eThree pasuho and two susuho survive\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Category\"\u003ePreservation\u003c/td\u003e\n\u003ctd data-label=\"Jagyeongnu under Sejong\"\u003eOriginal instrument has not survived\u003c/td\u003e\n\u003ctd data-label=\"Surviving vessels of the Changgyeonggung Palace Jagyeongnu\"\u003eWater vessels survive\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe remaining vessels alone cannot show the full automatic time-signal mechanism. The susuho bear inscriptions naming the participants in their construction and their posts. The inscription on the large pasuho provides evidence for the construction date. The surviving objects are confirmed as part of the National Palace Museum of Korea’s collection. \u003ca href=\"https://www.gogung.go.kr/gogung/pgm/psgudMng/view.do?menuNo=800065\u0026amp;psgudSn=370348\"\u003eNational Palace Museum of Korea collection description\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#records-and-interpretation\" class=\"anchor\" id=\"records-and-interpretation\"\u003e\u003c/a\u003eRecords and interpretation\u003c/h2\u003e\n\u003cp\u003eFacts recorded directly must be distinguished from later accounts. The annals are the key source confirming Jang Yeong-sil’s contribution to making the Jagyeongnu and the start of its use. His childhood and later years are not known to the same degree.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#facts-confirmed-by-records\" class=\"anchor\" id=\"facts-confirmed-by-records\"\u003e\u003c/a\u003eFacts confirmed by records\u003c/h3\u003e\n\u003cp\u003eThe 1433 annals state that Sejong recognized Jang Yeong-sil’s contribution to the construction. The 1434 entry describes the structure of the new water clock. The 1437 entry records the adoption of a method for relaying time signals.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#meaning-shared-by-the-explanatory-accounts\" class=\"anchor\" id=\"meaning-shared-by-the-explanatory-accounts\"\u003e\u003c/a\u003eMeaning shared by the explanatory accounts\u003c/h3\u003e\n\u003cp\u003eOur History Net explains that automatic time signals reduced the attendants’ workload. This interprets the mechanism as connecting time measurement and announcement. It should not, however, be taken to mean that the device was entirely free of error.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#conflicting-or-unconfirmed-details\" class=\"anchor\" id=\"conflicting-or-unconfirmed-details\"\u003e\u003c/a\u003eConflicting or unconfirmed details\u003c/h3\u003e\n\u003cp\u003eThe annals and the \u003cem\u003eAsan Jang Clan Genealogy\u003c/em\u003e give different accounts of his family background. They disagree on when his ancestors came from China to settle in Korea and on their lineage. The exact date of his appointment to the \u003cem\u003ebyeoljwa\u003c/em\u003e post at the Royal Wardrobe Office is also difficult to establish.\u003c/p\u003e\n\u003cp\u003ePunishment and dismissal followed the 1442 palanquin accident. His subsequent activities and the date of his death are unknown. Neither a year of death nor a place of retirement can be established from this. Stories about his childhood and scenes in dramas must also be distinguished from historical sources. \u003ca href=\"https://contents.history.go.kr/mobile/kc/view.do?levelId=kc_n310300\"\u003eOur History Net’s review of his life and the records\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#why-automatic-time-signals-matter-today\" class=\"anchor\" id=\"why-automatic-time-signals-matter-today\"\u003e\u003c/a\u003eWhy automatic time signals matter today\u003c/h2\u003e\n\u003cp\u003eThe Jagyeongnu is an example of a machine that conveyed measured information at the moment it was needed. It converted the continuous change in water level into signals at set times. Those signals were conveyed by sound and displays by figures.\u003c/p\u003e\n\u003cp\u003eWhat can be compared with automation today is the connection between functions. The breakdown below is a modern way to analyze the device. It does not mean the technology was the same as electronics or computers.\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eMeasurement: The flow of water and the height of the rod indicated elapsed time.\u003c/li\u003e\n\u003cli\u003eActivation: At a set position, a ball was released to move the next mechanism.\u003c/li\u003e\n\u003cli\u003eAnnouncement: A bell, drum, gong and time plaque announced the time.\u003c/li\u003e\n\u003cli\u003eOperation: The water had to be changed, and seasonal adjustments were needed.\u003c/li\u003e\n\u003c/ul\u003e\n\u003ch2\u003e\n\u003ca href=\"#frequently-asked-questions\" class=\"anchor\" id=\"frequently-asked-questions\"\u003e\u003c/a\u003eFrequently asked questions\u003c/h2\u003e\n\u003ch3\u003e\n\u003ca href=\"#was-the-jagyeongnu-made-in-1433-or-1434\" class=\"anchor\" id=\"was-the-jagyeongnu-made-in-1433-or-1434\"\u003e\u003c/a\u003eWas the Jagyeongnu made in 1433 or 1434?\u003c/h3\u003e\n\u003cp\u003eOur History Net gives 1433 as the year of completion. That year’s annals also mention the contribution made by building the Jagyeokgungnu. The new water clock came into use on the 1st day of the 7th lunar month of 1434.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#did-automatic-time-signals-eliminate-the-need-for-people\" class=\"anchor\" id=\"did-automatic-time-signals-eliminate-the-need-for-people\"\u003e\u003c/a\u003eDid automatic time signals eliminate the need for people?\u003c/h3\u003e\n\u003cp\u003eThe main task automated was determining and announcing the time. The annals say the susuho were used alternately when the water was changed. Maintenance also included changing parts to suit the seasonal divisions.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#are-the-jagyeongnu-and-borugak-the-same-thing\" class=\"anchor\" id=\"are-the-jagyeongnu-and-borugak-the-same-thing\"\u003e\u003c/a\u003eAre the Jagyeongnu and Borugak the same thing?\u003c/h3\u003e\n\u003cp\u003eThe Jagyeongnu was a water clock, while Borugak was the building where it was installed. Under Sejong, the Jagyeongnu operated at Borugak, south of Gyeonghoeru Pavilion in Gyeongbokgung Palace. For this reason, it was also called the Borugakru.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#did-jang-yeong-sil-make-the-museums-water-vessels-himself\" class=\"anchor\" id=\"did-jang-yeong-sil-make-the-museums-water-vessels-himself\"\u003e\u003c/a\u003eDid Jang Yeong-sil make the museum’s water vessels himself?\u003c/h3\u003e\n\u003cp\u003eThe surviving vessels are not the originals made by Jang Yeong-sil. They are part of the Jagyeongnu installed at Changgyeonggung Palace in 1536. Nor has the entire automatic time-signal mechanism from Sejong’s reign survived.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#did-jang-yeong-sil-die-in-1442\" class=\"anchor\" id=\"did-jang-yeong-sil-die-in-1442\"\u003e\u003c/a\u003eDid Jang Yeong-sil die in 1442?\u003c/h3\u003e\n\u003cp\u003eThe year 1442 appears in accounts of the palanquin accident and his punishment. The incident cannot be treated as a record of his death. His year of death is unknown.\u003c/p\u003e\n","tags":["Joseon period","Cultural heritage"],"faqs":[{"question":"What kind of clock is Jagyeongnu?","answer":"Jagyeongnu is a water clock that measures time using the flow of water and automatically signals the time. Beads and mechanical devices moved figures that rang a bell, beat a drum, and struck a gong."},{"question":"Was Jagyeongnu made in 1433 or 1434?","answer":"Our History Net gives 1433 as the year it was completed. The annals record that a new water clock was used starting on the first day of the seventh lunar month in 1434."},{"question":"How was the flow of water turned into a time signal?","answer":"As the water rose, a rod rose and activated a bead-release mechanism. The movement of the beads was transferred to other mechanical devices, causing the figures to signal the time."},{"question":"What did the bell, drum, and gong each signal?","answer":"The bell signaled the hour, the drum the night watch, and the gong a division of the night watch. Figures holding plaques marked with the time also appeared in turn."},{"question":"Did automatic time signaling eliminate the need for someone to maintain it?","answer":"Reading and announcing the time were automated, but maintenance was still necessary. The water had to be replaced, and parts had to be changed according to the solar terms."},{"question":"Are Jagyeongnu and Borugak the same thing?","answer":"Jagyeongnu is a water clock, while Borugak is the building where it was installed. The Jagyeongnu installed in Borugak was also called Borugaknu."},{"question":"Was the time kept by the royal court's Jagyeongnu also used outside the palace?","answer":"A 1437 entry in the annals records instructions to listen for the sound of Jagyeongnu and pass on a signal from an intermediate point. A system for relaying the signal as far as Uigeumbu was adopted."},{"question":"Is the Jagyeongnu that survives today the original made by Jang Yeong-sil?","answer":"The surviving Jagyeongnu water clock from Changgyeonggung Palace is part of an instrument made in 1536. The original instrument made by Jang Yeong-sil during King Sejong's reign has not survived."},{"question":"Which parts of Jagyeongnu still survive?","answer":"The National Palace Museum of Korea says that three water-supply vessels and two water-receiving vessels survive. The entire automatic time-signaling mechanism has not been preserved."},{"question":"What is the difference between Jagyeongnu and Angbuilgu?","answer":"Jagyeongnu is an automatic water clock that uses the flow of water. Angbuilgu is a sundial that uses the sun's shadow cast on a concave surface to tell the time and solar term."},{"question":"Did Jang Yeong-sil die in 1442?","answer":"The palanquin accident in 1442 cannot be taken as a record of his death. His subsequent activities and the year of his death remain unknown."}],"sources":[{"url":"https://sillok.history.go.kr/id/kda_11509016_003","title":"The Annals of King Sejong, 16th day of the 9th month in King Sejong's 15th year: Discussing the conferral of the additional office of hogun on Jang Yeong-sil","type":"source"},{"url":"https://sillok.history.go.kr/id/kda_11607001_004","title":"The Annals of King Sejong, 1st day of the 7th month in King Sejong's 16th year: The structure and operating principles of the newly made water clock and its inscription","type":"source"},{"url":"https://sillok.history.go.kr/id/wda_11906028_003","title":"The Annals of King Sejong, 28th day of the 6th month in King Sejong's 19th year: Ordering the bell marking the transition from night to dawn to be struck upon hearing the palace Jagyeongnu","type":"source"},{"url":"https://contents.history.go.kr/mobile/kc/view.do?code=kc_age_30\u0026levelId=kc_r300785","title":"National Institute of Korean History, Our History Net, Chronology of Korean History, “Jagyeongnu”","type":"source"},{"url":"https://contents.history.go.kr/mobile/tt/view.do?levelId=tt_b21","title":"National Institute of Korean History, Our History Net, “Astronomical Instruments and Calendrical Systems during King Sejong's Reign”","type":"source"},{"url":"https://contents.history.go.kr/mobile/kc/view.do?levelId=kc_n310300","title":"National Institute of Korean History, Our History Net, Chronology of Korean History, “Jang Yeong-sil”","type":"source"},{"url":"https://www.gogung.go.kr/gogung/pgm/psgudMng/view.do?menuNo=800065\u0026psgudSn=370348","title":"National Palace Museum of Korea Collection Guide, Changgyeonggung Palace Jagyeongnu Water Clock","type":"data_point"}],"images":[{"id":1830,"url":"https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MjgyMjEsInB1ciI6ImJsb2JfaWQifX0=--02ed33bf79e4f20fbde4076a857ce899059f1aab/ai-2b05b4af.webp","is_representative":false,"generation_method":"ai_semi","license":"ai_generated","mime_type":"image/webp","width":1536,"height":1024,"translations":{"ko":{"alt":"새벽 궁궐에서 관리인이 물을 돌보는 가운데, 물그릇들이 종·북·징 장치로 이어져 있다.","caption":"자격루는 사람이 눈금을 읽지 않아도 물의 흐름을 기계 신호로 바꿔 시각을 알렸다.","description":null},"en":{"alt":"At dawn, an attendant tends palace water-clock vessels beside a mechanism with a bell, drum and gong.","caption":"The Jagyeongnu turned flowing water into automatic time signals, replacing the need to read a scale.","description":null},"ja":{"alt":"夜明けの宮殿で係の者が水時計の容器を世話し、そばに鐘・太鼓・鉦の装置が並ぶ。","caption":"自撃漏は水の流れを機械信号に変え、目盛りを人が読まずに時刻を知らせた。","description":null},"es":{"alt":"Al amanecer, un encargado atiende los recipientes de un reloj de agua junto a una campana, un tambor y un gong.","caption":"El Jagyeongnu convertía el flujo del agua en avisos automáticos de la hora, sin tener que leer una escala.","description":null},"id":{"alt":"Saat fajar, seorang petugas mengurus bejana jam air istana di samping mekanisme lonceng, gendang, dan gong.","caption":"Jagyeongnu mengubah aliran air menjadi penanda waktu otomatis tanpa perlu membaca skala.","description":null},"pt":{"alt":"Ao amanhecer, um assistente cuida dos recipientes de um relógio de água junto a um sino, um tambor e um gongo.","caption":"O Jagyeongnu convertia o fluxo da água em avisos automáticos da hora, dispensando a leitura de uma escala.","description":null},"zh-hant":{"alt":"清晨的宮殿裡，侍者照料水鐘容器，旁邊設有鐘、鼓、鑼的機械裝置。","caption":"自擊漏將水流轉為機械訊號，無須由人讀取刻度便能自動報時。","description":null},"de":{"alt":"Im Morgengrauen betreut ein Diener die Gefäße einer Palast-Wasseruhr neben Glocke, Trommel und Gong.","caption":"Die Jagyeongnu wandelte fließendes Wasser in automatische Zeitsignale um, statt eine Skala ablesen zu lassen.","description":null}}},{"id":1831,"url":"https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MjgyMjcsInB1ciI6ImJsb2JfaWQifX0=--63efa05dc2ea8846dfd6da043fe0f6e3e57d5e95/ai-9d531284.webp","is_representative":false,"generation_method":"ai_semi","license":"ai_generated","mime_type":"image/webp","width":1536,"height":1024,"translations":{"ko":{"alt":"넓은 궁궐 뜰에서 북과 징 옆에 두 수행원이 등을 보이고 서 있다.","caption":"1437년에는 궁중 자격루의 시보를 의금부까지 전달하는 방식이 채택됐다.","description":null},"en":{"alt":"Two attendants stand with their backs turned beside a drum and gong in a broad palace courtyard.","caption":"In 1437, a method was adopted to relay the palace water clock’s time signal to Uigeumbu.","description":null},"ja":{"alt":"広い宮殿の中庭で、二人の従者が太鼓と銅鑼のそばに背を向けて立っている。","caption":"1437年、宮中の自撃漏の時報を義禁府まで伝える方式が採用された。","description":null},"es":{"alt":"Dos asistentes, vistos de espaldas, están junto a un tambor y un gong en un amplio patio palaciego.","caption":"En 1437 se adoptó un método para transmitir la señal horaria del reloj de agua palaciego hasta el Uigeumbu.","description":null},"id":{"alt":"Dua petugas tampak dari belakang di samping genderang dan gong di halaman istana yang luas.","caption":"Pada 1437, cara meneruskan sinyal waktu jam air istana ke Uigeumbu mulai diterapkan.","description":null},"pt":{"alt":"Dois auxiliares, vistos de costas, estão junto a um tambor e um gongo num amplo pátio palaciano.","caption":"Em 1437, adotou-se um método para transmitir o sinal horário do relógio de água do palácio até o Uigeumbu.","description":null},"zh-hant":{"alt":"寬闊的宮廷院落裡，兩名背對觀者的侍從站在鼓和鑼旁。","caption":"1437年，宮中自擊漏的報時訊號傳至義禁府的方式獲得採用。","description":null},"de":{"alt":"Zwei Bedienstete stehen mit dem Rücken zum Betrachter neben Trommel und Gong in einem weiten Palasthof.","caption":"1437 wurde ein Verfahren eingeführt, um das Zeitsignal der Palastwasseruhr an das Uigeumbu weiterzuleiten.","description":null}}}],"published_at":"2026-10-14T17:16:14+09:00","updated_at":"2026-10-14T17:16:14+09:00","license":"cc_by","translation_status":"reviewed","available_locales":["ko","en","ja","es"],"data_locales":["ko","en","ja","es","id","pt","zh-hant","de"],"url":"https://injoys.com/en/articles/jang-yeong-sil-jagyeongnu-making-and-automatic-time-signals"}