Science and technology of the Han dynasty

With the drilling of deep boreholes into the earth, the Chinese used not only derricks to lift brine up to the surface to be boiled into salt, but also set up bamboo-crafted pipeline transport systems which brought natural gas as fuel to the furnaces.

[10] The oldest known piece of paper with writing on it comes from the ruins of a Chinese watchtower at Tsakhortei, Alxa League, Inner Mongolia, dated to 110 CE when the Han garrison abandoned the area following a nomadic Xiongnu attack.

[27] Farmers, carpenters, craftsmen, stonemasons, and rammed earth builders had at their disposal iron tools such as the plowshare, pickaxe, spade, shovel, hoe, sickle, axe, adze, hammer, chisel, knife, saw, scratch awl, and nails.

[28] Common iron commodities found in Han dynasty homes included tripods, stoves, cooking pots, belt buckles, tweezers, fire tongs, scissors, kitchen knives, fish hooks, and needles.

[69] To better prepare for calamities, Zhang Heng invented a seismometer in 132 CE, which provided instant alert to authorities in the capital Luoyang that an earthquake had occurred in a location indicated by a specific cardinal or ordinal direction.

[71] Zhang called his device the 'instrument for measuring the seasonal winds and the movements of the Earth' (Houfeng didong yi 候风地动仪), so-named because he and others thought that earthquakes were most likely caused by the enormous compression of trapped air.

[72] As described in the Book of the Later Han, the frame of the seismometer was a domed bronze vessel in the shape of a wine jar, although it was 1.8 m (5.9 ft) in diameter and decorated with scenes of mountains and animals.

[76] Since the Book of the Later Han states that the other seven dragon heads would not subsequently release the balls lodged up into their jaws after the first one had dropped, Imamura asserted that the pin of the pendulum would have been locked into the slot it had entered and thus immobilized the instrument until it was reset.

[99] Later, the prince Zhu Zaiyu (1536–1611) in Ming China and Simon Stevin (1548–1620) of the Flemish Region in Europe would simultaneously (but separately) discover the mathematical formula for equal temperament.

[113] Besides the use of the calendar for regulating agricultural practices throughout the seasons, it was also used to mark important dates in the Sexagenary cycle—constructed by celestial stems (gan 干) and Earthly Branches (zhi 支), each of the latter associated with an animal of the Chinese zodiac.

[79] The latter astronomical theory was mentioned by Yang Xiong in his Model Sayings (Fayan 法言) and expounded on by Zhang Heng in his Spiritual Constitution of the Universe (Lingxian 靈憲) of 120 CE.

[119] However, due to wood's decay over time and susceptibility to fire, the oldest wooden buildings found in China (i.e. several temple halls of Mount Wutai) date no earlier than the Tang dynasty (618–907).

[122] Sections of the Han-era rammed earth Great Wall still exist in Gansu province, along with the Han frontier ruins of thirty beacon towers and two fortified castles with crenellations.

[129] The drainage system included many drainholes that were dug under these gates and lined with bricks that form arches, where ceramic water pipes have been found that once connected to the ditches built alongside the major streets.

[134] The rammed earth foundational platforms of religious altars and terraces still stand today outside of the walled perimeter of Luoyang, dedicated to the worship of deities and where state sacrifices were conducted.

[147] Mining shafts dating to the Han dynasty have been found which reach depths of hundreds of meters (feet) beneath the earth, complete with spacious underground rooms structured by timber frames along with ladders and iron tools left behind.

[148] There are Han-era literary references to tall towers found in the capital cities; they often served as watchtowers, astronomical observatories, and religious establishments meant to attract the favor of immortals.

[155] Even models of single-story farmhouses show a great amount of detail, including tiled roofs, courtyards, steps leading to walkways, farmyards with troughs and basins, parapets, and privies.

[158] In order to facilitate commerce and communication as well as speed the process of tax collection and movement of military troops, the Han government sponsored the building of new roads, bridges, and canal waterways.

[168] Evidence for arch bridges is elusive: one outside of Chengdu's south gate is claimed to date to the Han period, while that built by Ma Xian (Chinese: 馬賢) (fl.

[170] Although there are rare references to simple suspension bridges in Han sources, these are only mentioned in connection with travels to foreign countries in the Himalaya, Hindukush and Afghanistan, demonstrating the antiquity of the invention there.

[172] Much of the beliefs held by Han-era physicians are known to modern historians through such texts as the Yellow Emperor's Inner Canon (Huangdi neijing) medical corpus, which was compiled from the 3rd to 2nd century BCE and was mentioned in the Book of Later Han.

[173] The Han Chinese also believed that by using pulse diagnosis, a physician could determine which organ of the body emitted "vital energy" (qi) and what qualities the latter had, in order to figure out the exact disorder the patient was suffering.

[176] The Huangdi neijing noted the symptoms of people with various diseases of the liver, heart, spleen, lung, or kidneys in a 24-hour period, which was a recognition of circadian rhythm, although explained in terms of the five phases.

[177] In his Essential Medical Treasures of the Golden Chamber (Jinkui yaolue), Zhang Zhongjing (c. 150 – c. 219 CE) was the first to suggest a regulated diet rich in certain vitamins could prevent different types of disease, an idea which led Hu Sihui (fl.

[188] The Rites of Zhou (Zhouli), compiled during the Han and commented by Liu Xin in the 1st century CE, mentioned the use of maps for governmental provinces and districts, principalities, frontier boundaries, and locations of ores and minerals for mining facilities.

In 111 BCE, Emperor Wu conquered the Kingdom of Nanyue in what is now modern northern Vietnam and Guangdong, Guangxi, Yunnan; thereafter he opened up maritime trade to both Southeast Asia and the Indian Ocean, as foreign merchants brought lapis lazuli, pearls, jade, and glasswares to the Han Empire.

[198] Since the Chinese junk lacked a sternpost, the rudder was attached to the back of the ship by use of either socket-and-jaw or block and tackle (which differed from the later European pintle and gudgeon design of the 12th century).

In quelling a peasant revolt near Guiyang in 178 CE, the imperial Han forces had horse-drawn chariots carrying bellows that were used to pump powdered lime (calcium oxide) at the rebels.

[207] To deter pursuits of marching infantry or riding cavalry, the Han Chinese made caltrops (barbed iron balls with sharp spikes sticking out in all directions) that could be scattered on the ground and pierce the feet or hooves of those who were unaware of them.