一行
The elephant clock was a medieval invention by Ismail al-Jazari (1136–1206), an engineer and inventor of various clocks. The device consisted of a weight powered water clock in the form of an Asian elephant. The various elements of the clock are in the housing (howdah) on top of the elephant. In China a clock escapement mechanism was invented by the polymath Buddhist monk Yi Xing. Hydraulically powered waterwheels and water clocks were also used in the mechanically driven and rotated equatorial armillary sphere of Zhang Heng and Ma Jun. The elephant clock had some design differences compared to earlier waterclocks.