Science and technology of the Song dynasty

Polymaths—that is, people knowledgeable across an encyclopaedic range of topics—such as Shen Kuo (1031–1095) and Su Song (1020–1101) embodied the spirit of early empirical science and technology in the Song era. Shen is famous for discovering the concept of true north and magnetic declination towards the North Pole by calculating a more accurate measurement of the astronomical meridian, and fixing the calculated position of the pole star that had shifted over the centuries.[3] This allowed sailors to navigate the seas more accurately with the magnetic needle compass, also first described by Shen.[3] Shen was made famous for his written description of Bi Sheng, the inventor of movable type printing. Shen was also interested in geology, as he formulated a theory of geomorphology and climate change over time after making observations of strange natural phenomena.[4][5] Using contemporary knowledge of solar eclipses and lunar eclipses, he theorized that the sun and moon were spherical in shape, not flat, while expanding upon the reasoning of earlier Chinese astronomical theorists.[6] Along with his colleague Wei Pu in the Bureau of Astronomy, Shen used cosmological hypotheses when describing the variations of planetary motion, including retrogradation.[7][8] One of Shen's greatest achievements, aided by Wei Pu, was correcting the lunar error by diligently recording and plotting the moon's orbital path three times a night over a period of five years.[9] Unfortunately Shen had many political rivals at court who were determined to sabotage his work. The court fully accepted their corrections to lunar and solar error, but only partially adopted Shen and Wei's corrected plotting of the planetary orbital paths and various speeds.[9]

Su Song, one of Shen Kuo's political rivals at court, wrote a famous pharmaceutical treatise in 1070 known as the Bencao Tujing, which included related subjects on botany, zoology, metallurgy, and mineralogy.[10][11] This treatise included many medicinal applications, including the use of ephedrin as a pharmaceutical drug.[12] He also was the author of a large celestial atlas of five different star maps,[13] and his extensive written and illustrative work in cartography helped solve a heated border dispute between the Song dynasty and its Khitan neighbor of the Liao dynasty.[14] However, Su was most famous for his hydraulic-powered astronomical clock tower, crowned with a mechanically driven armillary sphere, which was erected in the capital city of Kaifeng in the year 1088.[15] Su's clock tower employed the escapement mechanism two centuries before it was applied in clocks of Europe.[16][17] Su's clock tower also featured the earliest known endless power-transmitting chain drive in the world, as outlined in his horological treatise of 1092.[18] The cases of these two men display the eagerness of the Song in drafting highly skilled officials who were knowledgeable in the various sciences which could ultimately benefit the administration, the military, the economy, and the people.

One of five star maps published in Su Song's horological and astronomical book of 1092 CE, featuring Shen Kuo's corrected position of the pole star as well as a cylindrical projection similar to Mercator projection

Intellectual men of letters like the versatile Shen Kuo dabbled in subjects as diverse as mathematics, geography, geology, economics, engineering, medicine, art criticism, archaeology, military strategy, and diplomacy, among others.[19][20] On a court mission to inspect a frontier region, Shen Kuo once made a raised-relief map of wood and glue-soaked sawdust to show the mountains, roads, rivers, and passes to other officials.[19] He once computed the total number of possible situations on a game board, another time the longest possible military campaign given the limits of human carriers who would bring their own food and food for other soldiers.[19] Shen Kuo is also noted for improving the designs of the inflow clepsydra clock for a more efficient higher-order interpolation, the armillary sphere, the gnomon, and the astronomical sighting tube; increasing its width for better observation of the pole star and other celestial bodies.[21] Shen Kuo also experimented with camera obscura, only a few decades after the first to do so, Ibn al-Haytham (965–1039).[22]

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: [...][23]

What follows is a long dissertation made by the Chief Chamberlain Lu Daolong on the ranging measurements and sizes of wheels and gears.[23] 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.[24]

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.[25] 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.[25] 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.[26]

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).

The Longxing Monastery, home to the oldest extant Chinese mechanical revolving-repository book case.

Revolving book case in Yingzao Fashi

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,[27] they came to prominence during the Song dynasty.[27] The invention of the revolving book case is considered to have happened earlier, and is credited to the layman Fu Xi in 544.[28] 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.[28] Furthermore, the oldest surviving rotating book case dates to the Song period (12th century), found at the Longxing Monastery of Zhengding, Hebei province.[27][29] 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.[27][30] The rotating repository of 1119 in Kaifu Temple near Changsha had five wheels which all turned together,[31] 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).[31] 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![32]

Detail of The Spinning Wheel, by Wang Juzheng, Northern Song era (960–1127).

In the field of manufacturing textiles, Joseph Needham (1900–1995) wrote that the Chinese invented the quilling-wheel by the 12th century,[33] and wrote the mechanical belt drive was known since the 11th century.[34] 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.[33] In this device the ramping arm of the flyer was activated simultaneously by a subsidiary belt drive.[33] This machine was portrayed in an illustration of the Geng Zhi Tu book of 1237,[35] and again a more elaborate illustration was provided in a 17th-century book.[33] 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.[34]

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).[34]

Advances in military technology aided the Song dynasty in its defense against hostile neighbors to the north. The flamethrower found its origins in Byzantine-era Greece, employing Greek fire (a chemically complex, highly flammable petrol fluid) in a device with a siphon hose by the 7th century.[45] The earliest reference to Greek Fire in China was made in 917, written by Wu Renchen in his Spring and Autumn Annals of the Ten Kingdoms.[46] In 919, the siphon projector-pump was used to spread the 'fierce fire oil' that could not be doused with water, as recorded by Lin Yu in his Wuyue Beishi, hence the first credible Chinese reference to the flamethrower employing the chemical solution of Greek fire (see also Pen Huo Qi).[47] Lin Yu mentioned also that the 'fierce fire oil' derived ultimately from one of China's maritime contacts in the 'southern seas', Arabia (Dashiguo).[48] In the Battle of Langshan Jiang in 919, the naval fleet of the Wenmu King from Wuyue defeated a Huainan army from the Wu state; Wenmu's success was facilitated by the use of 'fire oil' ('huo you') to burn their fleet, signifying the first Chinese use of gunpowder in a battle.[49] The Chinese applied the use of double-piston bellows to pump petrol out of a single cylinder (with an upstroke and downstroke), lit at the end by a slow-burning gunpowder match to fire a continuous stream of flame.[48] This device was featured in description and illustration of the Wujing Zongyao military manuscript of 1044.[48] In the suppression of the Southern Tang state by 976, early Song naval forces confronted them on the Yangtze River in 975. Southern Tang forces attempted to use flamethrowers against the Song navy, but were accidentally consumed by their own fire when violent winds swept in their direction.[50]

A Chinese flamethrower from the Wujing Zongyao manuscript of 1044 CE, Song dynasty

Although the destructive effects of gunpowder were described in the earlier Tang dynasty by a Daoist alchemist, the earliest-known existent written formulas for gunpowder come from the Wujing Zongyao text of 1044, which described explosive bombs hurled from catapults.[51] The earliest developments of the gun barrel and the projectile-fire cannon were found in late Song China. The first art depiction of the Chinese 'fire lance' (a combination of a temporary-fire flamethrower and gun) was from a Buddhist mural painting of Dunhuang, dated circa 950.[52] These 'fire-lances' were widespread in use by the early 12th century, featuring hollowed bamboo poles as tubes to fire sand particles (to blind and choke), lead pellets, bits of sharp metal and pottery shards, and finally large gunpowder-propelled arrows and rocket weaponry.[53] Eventually, perishable bamboo was replaced with hollow tubes of cast iron, and so too did the terminology of this new weapon change, from 'fire-spear' ('huo qiang') to 'fire-tube' ('huo tong').[54] This ancestor to the gun was complemented by the ancestor to the cannon, what the Chinese referred to since the 13th century as the 'multiple bullets magazine erupter' ('bai zu lian zhu pao'), a tube of bronze or cast iron that was filled with about 100 lead balls.[55] In 1132, at the siege of De'an, Song Chinese forces used fire lances against the rival Jurchen-led Jin dynasty.[56]

An early known depiction of a gun is a sculpture from a cave in Sichuan, dating to 1128, that portrays a figure carrying a vase-shaped bombard, firing flames and a cannonball.[57] However, the oldest existent archaeological discovery of a metal barrel handgun is the Heilongjiang hand cannon from the Chinese Heilongjiang excavation, dated to 1288.[58] The Chinese also discovered the explosive potential of packing hollowed cannonball shells with gunpowder. Written later by Jiao Yu in his Huolongjing (mid 14th century), this manuscript recorded an earlier Song-era cast-iron cannon known as the 'flying-cloud thunderclap eruptor' (fei yun pi-li pao). The manuscript stated that:

The shells are made of cast iron, as large as a bowl and shaped like a ball. Inside they contain half a pound of 'magic' gunpowder. They are sent flying towards the enemy camp from an eruptor; and when they get there a sound like a thunder-clap is heard, and flashes of light appear. If ten of these shells are fired successfully into the enemy camp, the whole place will be set ablaze...[59]

An illustration of a trebuchet catapult, as described in the Wujing Zongyao of 1044.

As noted before, the change in terminology for these new weapons during the Song period were gradual. The early Song cannons were at first termed the same way as the Chinese trebuchet catapult. A later Ming dynasty scholar known as Mao Yuanyi would explain this use of terminology and true origins of the cannon in his text of the Wubei Zhi, written in 1628:

The Song people used the turntable trebuchet, the single-pole trebuchet and the squatting-tiger trebuchet. They were all called 'fire trebuchets' because they were used to project fire-weapons like the (fire-)ball, (fire-)falcon, and (fire-)lance. They were the ancestors of the cannon.[60]

The 14th century Huolongjing was also one of the first Chinese texts to carefully describe to the use of explosive land mines, which had been used by the late Song Chinese against the Mongols in 1277, and employed by the Yuan dynasty afterwards.[61] The innovation of the detonated land mine was accredited to one Luo Qianxia in the campaign of defense against the Mongol invasion by Kublai Khan,[61] Later Chinese texts revealed that the Chinese land mine employed either a rip cord or a motion booby trap of a pin releasing falling weights that rotated a steel flint wheel, which in turn created sparks that ignited the train of fuses for the land mines.[62]

Furthermore, the Song employed the earliest known gunpowder-propelled rockets in warfare during the late 13th century,[63] its earliest form being the archaic fire arrow. When the Northern Song capital of Kaifeng fell to the Jurchens in 1126, it was written by Xia Shaozeng that 20,000 fire arrows were handed over to the Jurchens in their conquest.[64] An even earlier Chinese text of the Wujing Zongyao ("Collection of the Most Important Military Techniques"), written in 1044 by the Song scholars Zeng Kongliang and Yang Weide, described the use of three spring or triple bow arcuballista that fired arrow bolts holding gunpowder packets near the head of the arrow.[64] Going back yet even farther, the Wu Li Xiao Shi (1630, second edition 1664) of Fang Yizhi stated that fire arrows were presented to Emperor Taizu of Song (r. 960–976) in 960.[65]

"Angler on a Wintry Lake", painted in 1195 by Ma Yuan, featuring the oldest known depiction of a fishing reel[75]

The Chinese of the Song dynasty were adept sailors who traveled to ports of call as far away as Fatimid Egypt. They were well equipped for their journeys abroad, in large seagoing vessels steered by stern-post rudders and guided by the directional compass. Even before Shen Kuo and Zhu Yu had described the mariner's magnetic needle compass, the earlier military treatise of the Wujing Zongyao in 1044 had also described a thermoremanence compass.[76] This was a simple iron or steel needle that was heated, cooled, and placed in a bowl of water, producing the effect of weak magnetization, although its use was described only for navigation on land and not at sea.[76]

Detail of river vessels docking at Kaifeng, from Along the River During Qingming Festival, by Zhang Zeduan (1085–1145).

Another close-up view of the detail of Along the River.

There were plenty of descriptions in Chinese literature of the time on the operations and aspects of seaports, maritime merchant shipping, overseas trade, and the sailing ships themselves. In 1117, the author Zhu Yu wrote not only of the magnetic compass for navigation, but also a hundred-foot line with a hook that was cast over the deck of the ship, used to collect mud samples at the bottom of the sea in order for the crew to determine their whereabouts by the smell and appearance of the mud.[77] In addition, Zhu Yu wrote of watertight bulkhead compartments in the hulls of ships to prevent sinking if damaged, the for-and-aft lug, taut mat sails, and the practice of beating-to-windward.[78] Confirming Zhu Yu's writing on Song dynasty ships with bulkhead hull compartments, in 1973 a 78-foot (24 m) long, 29-foot (8.8 m) wide Song trade ship from c. 1277 was dredged from the water near the southern coast of China that contained 12 bulkhead compartment rooms in its hull.[79] Maritime culture during the Song period was enhanced by these new technologies, along with the allowance of greater river and canal traffic. All around there was a bustling display of government run grain-tax transport ships, tribute vessels and barges, private shipping vessels, a multitude of busy fishers in small fishing boats, along with the rich enjoying the comforts of their luxurious private yachts.[80]

Besides Zhu Yu there were other prominent Chinese authors of maritime interests as well. In 1178, the Guangzhou customs officer Zhou Qufei, who wrote in Lingwai Daida about the Arab slave trade of Africans as far as Madagascar,[81] stated this about Chinese seagoing ships, their sizes, durability at sea, and the lives of those on board:

A Song painting on silk of two Chinese cargo ships accompanied by a smaller boat; notice the large stern-mounted rudder on the ship shown in the foreground

A Song era junk ship, 13th century; Chinese ships of the Song period featured hulls with watertight compartments.

The ships which sail the southern sea and south of it are like houses. When their sails are spread they are like great clouds in the sky. Their rudders are several tens of feet long. A single ship carries several hundred men, and has in the stores a year's supply of grain. Pigs are fed and wine fermented on board. There is no account of dead or living, no going back to the mainland when once the people have set forth upon the caerulean sea. At daybreak, when the gong sounds aboard the ship, the animals can drink their fill, and crew and passengers alike forget all dangers. To those on board everything is hidden and lost in space, mountains, landmarks, and the countries of foreigners. The shipmaster may say 'To make such and such a country, with a favourable wind, in so many days, we should sight such and such a mountain, (then) the ship must steer in such and such a direction'. But suddenly the wind may fall, and may not be strong enough to allow of the sighting of the mountain on the given day; in such a case, bearings may have to be changed. And the ship (on the other hand) may be carried far beyond (the landmark) and may lose its bearings. A gale may spring up, the ship may be blown hither and thither, it may meet with shoals or be driven upon hidden rocks, then it may be broken to the very roofs (of its deckhouses). A great ship with heavy cargo has nothing to fear from the high seas, but rather in shallow water it will come to grief.[82]

The later Muslim Moroccan Berber traveler Ibn Battuta (1304–1377) wrote in greater detail about Chinese sailing vessels than Zhou Qufei. He noted that in and around the seas of China, only the distinct Chinese junks were used to sail the waters.[83] He noted that the largest type of Chinese ships boasted a total of twelve sailing masts, while the smaller ones had three.[83] On Chinese ships and their crews, Ibn Battuta stated:

The sails of these vessels are made of strips of bamboo, woven into the form of matting. The sailors never lower them (while sailing, but simply) change the direction of them according to whether the wind is blowing from one side or the other. When the ships cast anchor, the sails are left standing in the wind. Each of these ships is worked by 1,000 men, 600 sailors and 400 marines, among whom there are archers and crossbowmen furnished with shields, and men who throw (pots of) naptha. Each great vessel is followed by three others, a 'nisfi', a 'thoulthi' and a 'roubi' (f endnote: a pinnace, a small boat fitted with a rudder, and a rowing boat). These vessels are nowhere made except in the city of Zayton (Quanzhou) in China, or at Sin-Kilan, which is the same as Sin al-Sin (Guangzhou).[83]

Ibn Battuta then went on describing the means of their construction, and accurate depictions of separate bulkhead compartments in the hulls of the ships:

This is the manner in which they are made; two (parallel) walls of very thick wooden (planking) are raised, and across the space between them are placed very thick planks (the bulkheads) secured longitudinally and transversely by means of large nails, each three ells in length. When these walls have thus been built, the lower deck is fitted in, and the ship is launched before the upper works are finished. The pieces of wood, and those parts of the hull, near the water(-line) serve for the crew to wash and to accomplish their natural necessities. On the sides of these pieces of wood also the oars are found; they are as big as masts, and are worked by 10 or 15 men (each), who row standing up.[83]

Although Ibn Battuta had mentioned the size of the sailing crew, he described the sizes of the vessels further, as well as the lavish merchant cabins on board:

The vessels have four decks, upon which there are cabins and saloons for merchants. Several of these 'mysria' contain cupboards and other conveniences; they have doors which can be locked, and keys for their occupiers. (The merchants) take with them their wives and concubines. It often happens that a man can be in his cabin without others on board realizing it, and they do not see him until the vessel has arrived in some port. The sailors also have their children in such cabins; and (in some parts of the ship) they sew garden herbs, vegetables, and ginger in wooden tubs. The Commander of such a vessel is a great Emir; when he lands, the archers and the Ethiops (i.e. black slaves, yet in China these men-at-arms would have most likely been Malays) march before him bearing javelins and swords, with drums beating and trumpets blowing. When he arrives at the guesthouse where he is to stay, they set up their lances on each side of the gate, and mount guard throughout his visit.[84]

Paddle-wheel ship, 1726

During the Song dynasty there was also great amount of attention given to the building of efficient automotive vessels known as paddle wheel craft. The latter had been known in China perhaps since the 5th century,[85] and certainly by the Tang dynasty in 784 with the successful paddle wheel warship design of Li Gao.[85] In 1134, the Deputy Transport Commissioner of Zhejiang, Wu Ge, had paddle wheel warships constructed with a total of nine wheels and others with thirteen wheels.[86] However, there were paddle wheel ships in the Song that were so large that 12 wheels were featured on each side of the vessel.[87] In 1135 the famous general Yue Fei (1103–1142) ambushed a force of rebels under Yang Yao, entangling their paddle wheel craft by filling a lake with floating weeds and rotting logs, thus allowing them to board their ships and gain a strategic victory.[86] In 1161, gunpowder bombs and paddle wheel crafts were used effectively by the Song Chinese at the Battle of Tangdao and the Battle of Caishi along the Yangtze River against the Jurchen Jin dynasty during the Jin–Song Wars. The Jurchen invasion, led by Wanyan Liang (the Prince of Hailing), failed to conquer the Southern Song.[86]

In 1183, the Nanjing naval commander Chen Tang was given a reward for constructing ninety paddle wheel craft and other warships.[86] In 1176, Emperor Xiaozong of Song (r. 1162–1189) issued an imperial order to the Nanjing official Guo Gang (who desired to convert damaged paddle wheel craft into junk ships and galleys) not to limit the number of paddle wheel craft in the navy's dockyards, since he had high esteem for the fast assault craft that won the Chinese victory at Caishi.[88] However, paddle wheel craft found other uses besides effective assaults in warfare. The Arab or Persian Commissioner of Merchant Shipping for Quanzhou, the Muslim Pu Shougeng (who served from 1250 to 1275) noted that paddle wheel ships were also used by the Chinese as tugboats for towing.[89]