South Pointing Chariot
Supposedly invented sometime around 2600BC in China by the Yellow Emperor Huang Di, the South Pointing Chariot is widely regarded as the most complex geared mechanism of the ancient world. The chariot is a two-wheeled vehicle, upon which is a pointing figure connected to the wheels by means of differential gearing. Through careful selection of wheel size, track and gear ratios, the figure atop the chariot will always point in the same direction.
Legend
Legend has it that Huang Di, credited as being the founder of the Chinese nation, lived in a magnificent palace in the Kunlun Mountains.
There was also at this time another tribal leader, Chi You, who was skilled at making weapons and waging war. He attacked the tribe of Yan Di, driving them into the lands of Huang Di. Huang Di was angered by this and went to war with Chi You, initially suffering several defeats. At some stage in the fighting, Chi You conjured up a thick fog to confound Huang Di's men, however the South Pointing Chariot was used to find their way, and they were ultimately victorious.
Timeline
The South Pointing Chariot has been invented and reinvented at many times throughout Chinese history. Below is a partial timeline of the major events;
| Year | Event |
|---|---|
| 2634 BC | According to Legend, Huang Di, the Yellow Emperor designs the South Pointing Chariot. It is built for him by the craftsman Fang Bo |
| 1115 BC | During the reign of the Duke of Chou the Chinese Minister of State, Chou Kung, gives five such devices (called Chih-Nan) to ambassadors of Yüeh-Shang to get them back home |
| 120 .. 139 | Chang Hêng reinvents the vehicle |
| 220 .. 265 | Two scholars prove before the court that such a vehicle is impossible |
| 233 .. 237 | Ma Chün constructs a working vehicle for emperor Ming Ti |
| 300 | Tshui Pao reports, that the construction is described in a book (not preserved) named Shang Fang Ku Shih |
| 334 .. 349 | Hsieh Fei makes one for emperor Shih Hu |
| 394 .. 416 | Linghu Shêng makes one for emperor Yao Hsing |
| 417 | Linghu Shêng's vehicle is captured by emperor An Ti. It is reported that (at this time) there is no (longer any) machinery, but only a man inside who turns the figure. |
| 423 .. 452 | Kuo Shan-Ming fails to make one for emperor Thopa Tao |
| 423 .. 452 | Ma Yo succeeds, but is killed by Kuo Shan-Ming |
| 478 | Tsu Chhung-Chih makes a new improved (bronze gears) vehicle for emperor Shun Ti |
| 658 | Buddhist monk Chih-Yü (or Chiyu) constructs vehicle for Japanese emperor Wu |
| 666 | Monk Chih-Yu constructs another vehicle for Japanese emperor Wu |
| 806 .. 821 | Chin Kung-Li presents a south-pointing carriage to emperor Thang |
| 1027 | Engineer Yen Su (member of the "Board of Works") describes his construction (5 cogged, 4 non-cogged gear wheels, 18 soldier-drivers) |
| 1088 | Su Sung constructs a water wheel clock, using an escapement |
| 1107 | Chamberlain Wu Tê-Jen (Wu Tê-Lung or Wu De Ren according to other sources) presents a specification (24 cogged, 4 non-cogged gear wheels), which is successfully built twice |
| 1341 | Chu Tê-Jun describes a jade figure as (part of?) a miniature south-pointing carriage |
| 1720 | Joseph Williamson uses differential gear in clock |
| 1834 | J. Klaproth writes to Alexander von Humboldt, noting the south-pointing chariot chih-nan-ch´ê, but assumes that a magnetic compass is hidden in the little doll. |
| 1879 | Mr. Starley first uses differential gear in a vehicle |
| 1909 | Professor Giles points out, that the directional property of the south pointing chariot was effected by a mechanical system, and not by magnetism |
| 1909 | Professor Bertram Hopkinson (Cambridge) remarks, that some mechanism would have been required to ensure that the gears connected to the chariot wheels at right and left were engaged or disengaged when the chariot turned right or left. After some years of study, he declares that Yen Su's specification is insufficient to build a working model. |
| 1910 | The first mechanical navigation aide "Jones Live Map" is invented. Like in the south-pointing chariot the movement of the road wheels is geared down, but this time to show the relative position of the vehicle on a map |
| 1924 | Rev. A. C. Moule (Cambridge) proposes a realization of Wu Tê-Jen's specification, where the chariot is allowed to drive only straight lines. For each turn it is stopped, a gear connected and the turn done on the spot, the pointer now being corrected automatically |
| 1924 | K. T. Dykes is the first to propose a differential gearing, arguing that the clutch mechanism proposed by Moule is "slow and complicated to drive" |
| 1932 | Dr. J.B.Kramer discovers references to the mechanical nature of the south-pointing chariot and declares, that the Chinese therefore did not invent the magnetic compass |
| 1932 | George Lanchester proposes that the ancient machines (Ma Chün notably) embodied some kind of differential gear. He builds a working model to prove his concept. |
| 1937 | Wang Chen-To (Wang Zhenduo according to other sources) proposes a realization of Yen Su's specification and builds a working model from it |
| 1948 | Pao Ssu-ho (Bao Sihe according to other sources) proposes another reconstruction. |
| 1955 | F.W. Cousins introduces the Lanchester reconstruction to a broader public, namely the Meccanco fans |
| 1956 | J. Coales points out, that by hanging a carrot from the emperors hand, the south-pointing chariot would become self-steering ! |
| 1977 | Professor André Wegener Sleeswyk publishes a scientific essay on the historic chariots. He prooves their feasibility exactly to the words in the ancient texts. |
| 1978 | Mr. Alan Partridge starts a contest in The Meccano Magazine for the design with the fewest gears. It is shown subsequently that no gears are necessary at all ! |
| 1979 | Mr. Noel C. Ta'Bois publishes a concise treaty on the theoretical aspects. Working specimen are shown, which do not adhere to the "width equals wheel diameter" rule. |
| 1979 | Lu Zhiming produces three reconstructions based on differential gears |
| 1980 | Mr. Don Frantz from New York re-discovers the south pointing chariot, builds models along the Lanchester path and manages to place the in the Museum of the Province of Xian. |
| 1982 | Yan Zhiren builds another model, stressing that only differential gears provide the accuracy reported by the old writings |
| 1991 | Mr. M. Santander from Spain proposes to use the chariot to teach students the basic concepts of parallel transport and curvature. En passant a mathematical model is given for Mr. Nuttall's design. |
Where they can be seen
While none of the historic South Pointing Chariots remain, full sized replicas can be found.
The History Museum in Beijing, China holds a replica based on the mechanism of Yen Su (1027). The National Palace Museum in Taipei, Taiwan holds a replica based on the Lanchester mechanism of 1932.