The first group contains fixed meridian, horizon, and equatorial rings. The second group contains ecliptic, solstitial, and equinoctial rings that turn as a unit. The inner group contains one meridian ring that moves around the celestial pole. These allow the astronomer to set a celestial object within their sights and judge distance. The Simplified Instrument The simplified instrument serves a very similar purpose to the armillary sphere but has fewer parts. With only two sets of coordinates, this instrument has a larger range and vision than the armillary spheres. Yuan Gnomon The Yuan Gnomon is a shadow casting instrument used to measure the position of the sun. However, it does not appear to be very accurate. A crucial aspect of this mechanism was that it was oriented along the north–south meridian line, which allowed it to show the local noon. While not included in the 1392 list of official instruments, in 1437 Huangfu Zhonghe included it, likely due less to its practicality and more to the ingenuity behind it. Clepsydra The clepsydra, or water clock, was the most prevalent of time-keeping devices for astronomers. The clepsydra was also used as the official state time-keeping device. The Astronomical Bureau used a three chamber intake clepsydra, although there is no record of a water clock at Nanjing. It was not until the Bureau moved to Beijing that an official water hall was observed. Outside Perspective Because of the ideological importance of astronomy regarding politics, and the lack of precision by the instruments, many people believed the observations were false. Other recorded corruption such as accepting bribery, stealing, and not being punctual were also experienced. This led to a strict policy of punishment if the astronomers were found to be corrupt. Punishments included such actions as dismissal, deprivation of salary, or even beatings. Famous Chinese astronomers Gan De (4th century BCE) Shi Shen (4th century BCE) Zhang Heng (78 – 139 CE) Yu Xi (307 – 345 CE) Shen Kuo (1031 – 1095 CE) Su Song (1020 – 1101 CE) Guo Shoujing (1231 – 1316 CE) Xu Guangqi (1562 – 1633 CE) Wang Xishan 王錫闡 (1628 – 1682) Observatory Beijing Ancient Observatory Astro Observatory See also Book of Silk Chinese astrology Chinese constellations Chu Silk Manuscript Flat Earth in China History of astronomy Timeline of Chinese astronomy Traditional Chinese star names References Citations Sources Ho Peng Yoke. “THE ASTRONOMICAL BUREAU IN MING CHINA.”