14 Facts About South-pointing chariot

South-pointing chariot was an ancient Chinese two-wheeled vehicle that carried a movable pointer to indicate the south, no matter how the chariot turned.

Subsequently, whenever the South-pointing chariot turned, the mechanism rotated the pointer relative to the body of the South-pointing chariot to counteract the turn and keep the pointer aiming in a constant direction, to the south.

South-pointing chariot carriage was first constructed by the Duke of Zhou as a means of conducting homewards certain envoys who had arrived from a great distance beyond the frontiers.

South-pointing chariot was combined with the earlier Han Dynasty era invention of the odometer, a mechanical device used to measure distance traveled, and found in all modern automobiles.

The pointing doll was connected to Shaft A When the chariot moved in a straight line, the two wheels turned at equal speeds, and the doll did not rotate.

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South-pointing chariot used a differential for correcting the equation of time for a clock that displayed both mean and solar time.

Likewise, if a South-pointing chariot goes around a closed loop, starting and finishing at the same point on the Earth's surface, its pointer generally does not aim in the same direction at the finish as it did at the start.

Nevertheless, they show that this type of South-pointing chariot, based on differential gears, would be an imperfect compass even if constructed exactly and used in ideal conditions.

Simple geometry shows that if the chariot's mechanism is based on a differential gear and if, for example, the width of the track of the chariot is three metres, and if the wheels are intended to be identical but actually differ in diameter by one part in a thousand, then if the chariot travels one kilometre in a straight line, the "south-pointing" figure will rotate nearly twenty degrees.

However, it raises the problem of how the South-pointing chariot could have been kept travelling in straight lines with sufficient accuracy without using the pointing doll.

The fact that the sources cited above mention that the South-pointing chariot was placed at the front of processions, its high level of mechanical complexity and fragility, and that it was 'reinvented' several times contribute to the conclusion that it was not used for navigation, as a truly practical and useful navigational tool would not be forgotten or left unused.

Charioteer would have had to use great skill to ensure that the radius of each turn of the South-pointing chariot was correct to make one of the wheels exactly stop rotating.

South-pointing chariot would have been able to adjust the direction in which it aimed by making turns that were more or less sharp.

Some non-mechanical method of finding the south must have been used when a mechanical south-pointing chariot was initialized, aiming its pointer to the south at the start of a journey.