Ancient science and technology and the “Four Great Inventions”
4 min readChina has one of the world’s oldest agricultural traditions. Agriculture requires precise knowledge of the seasons. Consequently, the Chinese ancestors were diligent observers of celestial phenomena, and achieved a fairly advanced understanding of astronomy.A calendar known as the Taichu Calendar, based on exact empirical measurements, was in use during the HanDynasty(202 BC-220 AD). The Taichu Calendar calculated the precise relationship between the seasons and the cycles of the moon,a method that was to be utilized in the lunar calendar for the next 2,000 years. In order to observe seismic phenomena, the great Han Dynasty scientist Zhang Heng (78-139 AD) invented the seismograph,1,700 years before comparable in-struments appeared in Europe. Zhang Heng also made improvements on the armillary sphere, or celestial globe, used to observe celestial phenomena. During the Han Dynasty,a specialized government office called the Qin Tian Jian(Imperial Office of the Heavens) was established to carry out scientific research, observe celestial phenomena, and formulate the calendar. This office served as the Han Dynasty academy of sciences.
Observing and analyzing celestial phenomena requires advanced mathematical skills andeffective mathematical formulae. The Western Han (202 BC-9 AD) mathematical classic, the Zhoubi Suanjing (The Arithmetical Classic of the Zhou Gnomon), contains the earliest explication of what later became known as the Pythagorean theorem, as well as the theory of fractional operations. Mathematician Liu Hui(b.c.250 AD), who lived during the Three Kingdoms Period (220-280 AD), was the first person to propose the mathematical concept of limits. During the Northern and Southern Dynasties (420-589 AD) mathematician Zu Chongzhi(429-500 AD) precisely calculated the value of t(pi) to be between 3.1415926 and 3.1415927.
Although the earliest paper was quite coarse, compared to costly silk and cumbersome bamboo or wood it was both convenient and inexpensive. During the Eastern Han Dynasty (25-220AD), Cai Lun(d.121AD) introduced major improvements in papermaking methods and materials, producing paper that was uniform, smooth, and inexpensive to manufacture.
Chinese papermaking techniques were introduced to Korea during the Western and Eastern Jin dynasties(226-420 AD). By the time of the Tang Dynasty(618-907 AD), papermaking had spread to Japan and India, and later to Persia, northern Africa, and Europe. Replacing parch-ment in Europe, pattra leaves in India, and papyrus in Egypt, the introduction of paper as a writing material was enormously influential in promoting cultural exchange among various countries.
Moveable type was invented during the Qingli Reign（1041-1048 AD）of the Northern Song Dynasty（960-1127 AD）by a commoner named Bi sheng（d.c.1051 AD）.Bi sheng carved characters on individual clay blocks，then fired the blocks to harden them.Because each char acter had its own block，they could be freely arranged in any combination and reused many times，greatly increasing the efficiency of the typesetting and printing process.Moveable type appeared in Europe at the beginning of the Renaissance（c.14th-17th century AD），and was instrumental to Europe’s process of modernization.
The invention of the compass was yet another great contribution of the Chinese people to world civilization.The ability of natural magnets to indicate magnetic north and south was first discovered in China，leading to the invention of a direction-finding device known as the sinan（south-pointing ladle）during the Warring States Period（475-221 BC）.Over the ages，new methods of utilizing magnetism were developed.Mengxi Bitan（Essays from Mengxi Creek），by the eminent Song Dynasty scientist Shen Kuo（1031-109 5AD），includes a detailed description of the construction and use of the compass.The Song Dynasty saw the development of the floating compass.By suspending the magnetic needle in water，the effect of motion on the compass was minimized，enabling compasses to be installed on ships and used for maritime navigation for the first time.The floating compass spread to the Arab world，and on to Europe，where it was further refined into the dry compass.The dry compass eventually made its way back to China，where it replaced the floating compass.In this way，Chinese and foreign culture mutually influenced and benefited each other.
The invention of gunpowder had its origins in ancient Chinese alchemy.During the Sui Dynasty（581-618AD），alchemists searching for the formula for immortality discovered that by combining certain proportions of sulphur，potassium nitrate，and charcoal，a substance was produced that would violently explode when exposed to fire.This compound，known as black powder，was the earliest form of gunpowder.Descriptions of the formula for making gunpowder appear in records from the mid-Tang Dynasty（618-907 AD），and gunpowder weapons were used in a war that took place during the later Tang Dynasty.During the SongYuan period（960-1368 AD），gunpowder was widely used in military operations.As trade developed between China and other countries，and particularly with the western incursions of the Mongols，gunpowder and firearms were introduced to Europe via the Arab world.This new technology underwent rapid development in Europe，resulting in major changes in military affairs around the world.
