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Science and technology of the Song dynasty

Aspect of Chinese history

  • 36 min read
  • 11 chapters

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Through Compass, Hydraulics and Water clock

The ingenuity of advanced mechanical engineering had a long tradition in China. The Song engineer Su Song, who constructed a hydraulically-powered astronomical clocktower, admitted that he and his contemporaries were building upon the achievements of the ancients such as Zhang Heng (78–139), an astronomer, inventor, and early master of mechanical gears whose armillary sphere was automatically rotated by a waterwheel and clepsydra timer. The application of movable type printing advanced the already widespread use of woodblock printing to educate and amuse Confucian students and the masses. The application of new weapons employing the use of gunpowder enabled the Song to ward off its militant enemies—the Liao, Western Xia, and Jin with weapons such as cannons—until its collapse to the Mongol forces of Kublai Khan in the late 13th century.

Notable advances in civil engineering, nautics, and metallurgy were made in Song China, as well as the introduction of the windmill to China during the thirteenth century. These advances, along with the introduction of paper-printed money, helped revolutionize and sustain the economy of the Song dynasty. Song era antiquarians such as Ouyang Xiu (1007–1072) and Shen Kuo dabbled in the nascent field of archaeology and epigraphy, inspecting ancient bronzewares and inscriptions to understand the past. Advances were also made in the field of forensics, in particular by Song Ci (1186–1249), author of the Collected Cases of Injustice Rectified that covered topics such as autopsies in murder cases and first aid for victims.

Polymaths and mechanical engineering

Polymaths

Polymaths such as Shen Kuo (1031–1095) and Su Song (1020–1101) were active during the Song period, making contributions to technology and early empirical science. Shen described the concept of true north and magnetic declination toward the North Pole by refining measurements of the astronomical meridian and correcting the calculated position of the pole star. His work improved the accuracy of maritime navigation with the magnetic compass, which he also described in writing. Shen documented Bi Sheng’s invention of movable type printing and advanced geological theories, proposing long-term geomorphology and climate change on the basis of field observations. Drawing on knowledge of solar and lunar eclipses, he argued that the sun and moon were spherical, extending earlier Chinese astronomical ideas. Together with Wei Pu in the Bureau of Astronomy, Shen developed models for planetary motion, including retrograde motion, and carried out detailed observations of the moon’s orbital motion over five years. Their corrections to lunar and solar error were adopted at court, although revisions to planetary orbital paths were only partially accepted, possibly as a result of political opposition. Shen also conducted research in mathematics, geography, economics, medicine, art criticism, archaeology, military strategy, and diplomacy. He calculated the number of permutations in board games, modeled the maximum duration of a military campaign as a function of resupply logistics, improved scientific instruments such as the inflow clepsydra clock, the armillary sphere, the gnomon, and the astronomical sighting tube, and carried out early experiments with the camera obscura, following the earlier work of Ibn al-Haytham (965–1039).

Su Song (1020–1101), a contemporary of Shen Kuo, compiled the Bencao Tujing in 1070, a pharmaceutical treatise that included sections on botany, zoology, metallurgy, and mineralogy. The work documented a range of medicinal practices, including the use of ephedrin. Su also produced a celestial atlas containing five star maps. His writings on cartography were used to resolve a border dispute between the Song dynasty and the Liao dynasty. In 1088, he directed the construction of a hydraulic-powered astronomical clock tower in Kaifeng, which incorporated a mechanically driven armillary sphere. The clock employed an escapement mechanism two centuries before its documented use in European clocks, and featured a power-transmitting chain drive described in his horological treatise of 1092.

Odometer and south-pointing chariot

There were many other important figures in the Song era besides Shen Kuo and Su Song, many of whom contributed greatly to the technological innovations of the time period. Although the mechanically driven mile-marking device of the carriage-drawn odometer had been known in China since the ancient Han dynasty, the Song Shi (compiled in 1345) provides a much greater description and more in-depth view of the device than earlier Chinese sources. The Song Shi states:

The odometer. [The mile-measuring carriage] is painted red, with pictures of flowers and birds on the four sides, and constructed in two storeys, handsomely adorned with carvings. At the completion of every li, the wooden figure of a man in the lower storey strikes a drum; at the completion of every ten li, the wooden figure in the upper storey strikes a bell. The carriage-pole ends in a phoenix-head, and the carriage is drawn by four horses. The escort was formerly of 18 men, but in the 4th year of the Yongxi reign period (987) the emperor Taizong increased it to 30. In the 5th year of the Tian-Sheng reign-period (1027) the Chief Chamberlain Lu Daolong presented specifications for the construction of odometers as follows: [...]

What follows is a long dissertation made by the Chief Chamberlain Lu Daolong on the ranging measurements and sizes of wheels and gears. However, the concluding paragraph provides description at the end of how the device ultimately functions:

When the middle horizontal wheel has made 1 revolution, the carriage will have gone 1 li and the wooden figure in the lower story will strike the drum. When the upper horizontal wheel has made 1 revolution, the carriage will have gone 10 li and the figure in the upper storey will strike the bell. The number of wheels used, great and small, is 8 inches (200 mm) in all, with a total of 285 teeth. Thus the motion is transmitted as if by the links of a chain, the "dog-teeth" mutually engaging with each other, so that by due revolution everything comes back to its original starting point.

In the Song period (and once during the earlier Tang period), the odometer device was combined with the south-pointing chariot device, which was probably first invented by the ancient Chinese mechanical engineer Ma Jun (200–265). The south-pointing chariot was a wheeled vehicle that may, in some cases, have incorporated complex differential gears. (These are used now in nearly all modern automobiles to apply equal amounts of torque to wheels rotating at different speeds while turning.) The differential gears could have been used to keep a mechanically operated pointer aiming in a fixed direction, to the south, compensating for whatever turns the chariot made. Other arrangements of gears could also have been used for the same purpose. The device used mechanical dead reckoning, rather than the magnetism of a compass, in order to navigate and find one's directional bearings. Yan Su (燕肃; c. 961–1040), the Divisional Director in the Ministry of Works, recreated a south-pointing chariot device in 1027, and his specifications for creating the device were provided in the Song Shi. This is of little surprise, as Yan was somewhat of a polymath like Shen Kuo and Su Song, improving the design of the clepsydra clock, writing on mathematical harmonics, theory about tides, etc. The Song Shi text records that it was the engineer Wu Deren who combined the south-pointing chariot and odometer in the year 1107:

In the first year of the Da-Guan reign period (1107), the Chamberlain Wu Deren presented specifications of the south-pointing carriage and the carriage with the li-recording drum (odometer). The two vehicles were made, and were first used that year at the great ceremony of the ancestral sacrifice.

The text then went on to describe in full detail the intricate mechanical design for the two devices combined into one. (See the article on the south-pointing chariot).

Revolving repositories

Besides clockwork, hydraulic-powered armillary spheres, odometers, and mechanical compass vehicles, there were other impressive devices of mechanical engineering found during the Song dynasty. Although literary references for mechanical revolving repositories and book cases of Buddhist temples trace back to at least 823 during the Tang dynasty, they came to prominence during the Song dynasty. The invention of the revolving book case is considered to have happened earlier, and is credited to the layman Fu Xi in 544. Revolving bookcases were popularized in Buddhist monasteries during the Song dynasty under the reign of Emperor Taizu, who ordered the mass printing of the Buddhist Tripiṭaka scriptures. Furthermore, the oldest surviving rotating book case dates to the Song period (12th century), found at the Longxing Monastery of Zhengding, Hebei province. However, there were nine prominently known revolving repositories during the Song period, and one of them was even featured in an illustration of Li Jie's book Yingzao Fashi ('Treatise on Architectural Methods') of 1103. The rotating repository of 1119 in Kaifu Temple near Changsha had five wheels which all turned together, and the revolving repository at Nanchan Temple of Suzhou featured a brake system of some sort (sinologists are still uncertain how this operated, since the earliest known curve brake bands appear in the time of Leonardo da Vinci in Europe). A later Muslim traveler Shah Rukh (son of the Turco-Mongol warlord Timur) came to Ming dynasty China in 1420 during the reign of the Yongle Emperor, and described a revolving repository in Ganzhou of Gansu province that he called a 'kiosque':

In another temple there is an octagonal kiosque, having from the top to the bottom fifteen stories. Each story contains apartments decorated with lacquer in the Cathayan manner, with ante-rooms and verandahs...It is entirely made of polished wood, and this again gilded so admirably that it seems to be of solid gold. There is a vault below it. An iron shaft fixed in the center of the kiosque traverses it from bottom to top, and the lower end of this works in an iron plate, whilst the upper end bears on strong supports in the roof of the edifice which contains this pavilion. Thus a person in the vault can with a trifling exertion cause this great kiosque to revolve. All the carpenters, smiths, and painters in the world would learn something in their trades by coming here!

Textile machinery

In the field of manufacturing textiles, Joseph Needham (1900–1995) wrote that the Chinese invented the quilling-wheel by the 12th century, and wrote the mechanical belt drive was known since the 11th century. Qin Guan's book Can Shu (Book of Sericulture) of 1090 described a silk-reeling machine with an oscillating 'proto-flyer', as the apparatus of the main reel of which the silk is bound is wound and powered by treadle motion. In this device the ramping arm of the flyer was activated simultaneously by a subsidiary belt drive. This machine was portrayed in an illustration of the Geng Zhi Tu book of 1237, and again a more elaborate illustration was provided in a 17th-century book. Qin Guan's 1090 book stated that:

The pulley (bearing the eccentric lug) is provided with a groove for the reception of the driving belt, an endless band which responds to the movement of the machine by continuously rotating the pulley.

An endless rope or cord may have been used in Du Shi's device of waterwheels that powered bellows of the blast furnace in the 1st century (see Wind Power below).

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