Today I went to 'Seoul museum of history'. I will talk about Jang Yeong Sil's three inventions and how to use.

First his invention is Ja-gyeong-nu. Ja-gyeong-nu's another name is water clock. It uses with water. We can know what time is it with water.

Second invention is sun clock or sundial. Sun dial uses shadow by sun. On clock,there is number, then shadow points that number. For example, when shadow points number four, it will be four o'clock.

Last invention is Hon-cheon-i. It uses for look star or moon.

Ja-gyeong-nu and sundial are clock, Hon-cheon-i is not clock.

Today I learned many intresting things, and I want to go here again.