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 Main: A scene of the Qing dynasty campaign against the Miao (Hunan) 1795 (public domain). Inset: Model of a Chinese South Pointing Chariot, an early navigational device using a differential gear.

The South-Pointing Chariot: This Ancient Chinese Invention Led Armies In a Unique and Impressive Way

The south-pointing chariot is a Chinese invention that functioned in a similar way to a compass. Instead of pointing north, however, this device could point south, or any other direction it was ‘programmed’ to point in the first place, for that matter. The compass, which is regarded as one of the Four Great Inventions of the Chinese civilisation, functions based on the Earth’s magnetic field. The south-pointing chariot, on the other hand, worked based on mechanics.

Several figures from Chinese history have been credited with the invention of the south-pointing chariot. According to one legend, the south-pointing chariot was invented during the reign of the mythical Yellow Emperor, or Huangdi, who is credited also with a range of other inventions, including the calendar, astronomy, and cuju (an ancient Chinese football game). The story goes that the Yellow Emperor was at war with Chi You, the leader of the Nine Li tribe. During the Battle of Zhuolu, Chi You produced a fog that darkened the sky, thus causing the Yellow Emperor and his army to lose their sense of direction. In order to counter Chi You’s fog, the Yellow Emperor had his minister, Feng Hou, invent the south-pointing chariot. This invention allowed the Yellow Emperor and his troops to find their way through the fog, and defeat the enemy.

Model of a Chinese South Pointing Chariot, an early navigational device using a differential gear.

Model of a Chinese South Pointing Chariot, an early navigational device using a differential gear. (CC by SA 3.0 )

Another story claims that the south-pointing chariot was created during the early part of the Zhou Dynasty. During this time, the King of Zhou (either the first king, Wu, or his successor, Cheng) received an embassy from a tribe from far beyond the borders of his kingdom. This tribe wished to pay tribute to the Zhou king, which was accepted. In return, the envoys of this tribe were given gifts to bring home. Amongst these were a number of south-pointing chariots, which had been built by Duke Wen of Zhou. These devices were supposed to have guided the envoys back home.

It may be mentioned briefly that other figures credited with the invention of this device include the Zhang Heng, a polymath who lived during the Han Dynasty, and the famous mechanical engineer Ma Jun, who lived in the state of Cao Wei during the succeeding Three Kingdoms period.  

Unfortunately, if the south-pointing chariot had indeed been invented by any one of these famous Chinese figures, its technical specifications have not survived through the passage of time. According to one source, the earliest preserved description of a south-pointing chariot’s form and construction dates to the reign of the Emperor Renzong, the fourth ruler of the Song Dynasty. This description, which may be found in the Song Shi , provides us with the details of how the south-pointing chariot was made by Yan Su and Wu Deren, engineers who were in the service of the Song court.

A South-pointing Chariot

A South-pointing Chariot ( Internet Archive Book Images / Flickr )

Based on the technical description of Yan Su and Wu Deren’s south-pointing chariot, scholars are able to have an understanding of the way this device worked. In essence, the south-pointing chariot consists of a system of gears that was connected to a pointing figure. This figure could be set to point in any direction, and would continue to point in the same direction regardless of where the chariot moved. It is generally accepted it was the differential (a type of gear train), that made this possible. The best known use of this gear system today is in wheeled vehicles, such as cars. The differential allows the outer drive wheel to rotate faster than the inner drive wheel during a turn, which would allow traction to be maintained.

Replica of the South-pointing chariot in the China Court of the Ibn Battuta Mall, Dubai

Replica of the South-pointing chariot in the China Court of the Ibn Battuta Mall, Dubai ( CC by SA 4.0 )

As a navigator device, the south-pointing chariot would not have been quite accurate, unless it was regularly adjusted to correct the errors that arose over time. Nevertheless, if such a device was used for ceremonial purposes, for instance, to lead an imperial procession down a winding street, it would certainly have had an awe-inspiring effect on onlookers, who would probably have attributed the machine’s functioning to magic, rather than mechanics.

Top image: Main: A scene of the Qing dynasty campaign against the Miao (Hunan) 1795 (public domain). Inset: Model of a Chinese South Pointing Chariot, an early navigational device using a differential gear. (CC by SA 3.0 )

By Wu Mingren

References

Gu, H., 2016. The Compass. [Online]
Available at: http://www.chinatoday.com.cn/english/culture/2016-02/16/content_712997.htm

history-computer.com, 2018. South Pointing Chariot. [Online]
Available at: https://history-computer.com/CalculatingTools/AnalogComputers/South_pointing_chariot.html

Lienhard, J. H., 1997. No.414: South-pointing Chariot. [Online]
Available at: https://www.uh.edu/engines/epi414.htm

web.physics.ucsb.edu, 2018. South-pointing Chariot. [Online]
Available at: http://web.physics.ucsb.edu/~lecturedemonstrations/Composer/Pages/92.36.html

www.odts.de, 2018. South Pointing Chariots. [Online]
Available at: http://www.odts.de/southptr/

Yong, Y.-C.et al., 1986. Mechanism Design of South Pointing Chariots. [Online]
Available at: http://odts.de/southptr/tsai/Tsai_eng.pdf

Comments

It's a nice idea, but the wheels slip and the pointer drifts, modern-day accelerometers have the same issue, you need a known reference like north or the stars to bring them back in line. A bowl of water with another bowl inside with a piece of magnetite (natural iron magnetised by a lightning strike) is much more reliable.

The points of a crescent moon project to the horizon point south, as does the orions belt. The shortest shadow give a true bearing south. This contraption will drift around 10 degrees per mile on an rough track.

Nice article but I don’t know how it works as the article didn’t tell me.

DHWTY please tell me what does isquo and rsquo mean, please?

The gearing of the wheels is like a drive transmission train, on a car, but in reverse. Two bevel cogs connect to each wheel, with two interlocking cogs connecting them, when the wheels turn at the same rate they cancel out, but when they turn at a different rate, the whole mechanism rotates, this is connected by gears to the pointer. In theory maintaining the same direction due to the gearing ratios, In practice the wheels slips and the pointer drifts.

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