This is Heumgyeonggak, the royal science academy, where various astronomical tools are stored. Heumgyeonggak means ‘to respect the heavens and be aware of the time.’ In East Asian societies that were primarily agrarian, one of the king’s most important duties was to be familiar with climate changes and know exactly when was a good time of year to grow crops. In order to do this, marking the seasons was a very important task. This knowledge helped to stabilize the people by having good harvests, King Sejong employed Jang Yeongsil, a former house slave, to invent the sundial and the waterclock. Jang Yeongsil’s sundial was especially useful for farming because it could tell the exact season. This sundial was extremely effective and significantly increased agricultural output during this time. You can see the waterclock that Jang Yeongsil invented at the National Palace Museum at the entrance to Gyeongbokgung.