Kham Thien Giam (Directorate of Imperial Observatory) - This is one of the most important agencies representing the science, specifically here the astronomy, calendar, hydrometeorology of the Vietnamese in the nineteenth century. Not only expressing scientific functions, Kham Thien Giam also has a great impact on the social aspect, as the results from the compilation of calendars, astronomical observations, celestial objects, calculation of date and time, feng shui, geography, etc. of this agency had a profound influence on all activities of the emperor and court as well as agricultural production and all non-folk rituals.