South-pointing chariot
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The south-pointing chariot was an ancient Chinese two-wheeled vehicle that carried a movable pointer that indicated south, no matter how the chariot turned. Usually, the pointer took the form of a dol
Exhibit in the Science Museum in London, England. This conjectural model chariot incorporates a differential gear.
An image of a south-pointing chariot from Sancai Tuhui (first published 1609)
Children's instructive toy chariot in Chinese display at Expo 2005 in Japan
An illustration of a differential between the drive shaft (at bottom right) and driving wheels of an automobile
Dead reckoning
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In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed, heading, an
South-pointing chariot
…counteract the turn. This kept the pointer aiming in a constant direction, equal to the starting position. Thus the mechanism did a kind of directional dead reckoning, which is inherently prone to cumulative errors and uncertainties. Some chariots' mechanisms may have had differential gears. The south-pointing chariot…
Dead reckoning navigation tools in coastal navigation
British P10 Magnetic Compass with dead reckoning navigation tools