#khaifeng

The Khaifeng clock of 1090 was the creation of Su Sung, who first built a wooden pilot model, then cast his working parts in bronze. The water that supplied power was contained in a reservoir, refilled periodically by manually operated norias. Water passed by siphon from the reservoir to a constant-level tank and thence to the scoops of the waterwheel. An endless-chain drive slowly turned a celestial globe and an armillary sphere one revolution per day. The same waterwheel turned a series of shafts, gears, and wheels working the bells and drums that announced the time (like nearly all early mechanical clocks, Su Sung’s had no face). The escapement that was the ‘soul of the timekeeping machine’ and that kept its movement at an even pace was a complex arrangement of balances, counterweights, and locks that divided the flow of the water into equal parts by repeated weighing, automatically dividing the revolution of the wheel into equal interval.