Mechanical Clock – Yi Xing, a Buddhist monk, made the first model of a mechanical clock in 725 AD. This clock operated by dripping water that powered a wheel which made one full revolution in 24 hours. An iron and bronze system of wheels and gears made the clock turn. This system caused the chiming of a bell on the hour. Su Sung’s great ‘Cosmic Engine’ of 1092 was 35 feet high.