Chinese Astronomical Clock

The BBC’s History of the World in 100 Objects includes this remarkable astronomical clock, one of only two known examples worldwide. Its counterpart, in the Forbidden City at Beijing, differs from it only in minor details.
The outer brass rings can be used for telling the time in both Western and Chinese cultures. The inner brass ring marks the seasons. Each day this ring - together with the main dial - turns clockwise through one degree, thus making a full revolution in a year.
On the main face of the clock is a chart showing the brighter stars visible from Southern China. On the chart, the most prominent feature is the Milky Way (Tianhe ? the "Celestial River") but in all around 850 stars are represented by small red circles. These stars are joined into about 160 groups, representing the most significant of the traditional Chinese constellations.
The movement is Chinese, but it is based on an English design of around AD 1790. Parts of the movement, such as the short pendulum are unusual, suggesting that the maker was not copying a movement but working from sketches or notes and improvised where they were inadequate.