Domestic and Industrial Technology
Domestic and Industrial Technology
Cast Iron. The Chinese used blast furnaces for making cast iron as early as the fourth century B.C.E. The largest cast-iron building was a temple constructed in 688. Ordered by Empress Wu Zhao, this 284-foot-high building was in the form of a 3-story pagoda (300 square feet), and a 10-foot cast-iron phoenix covered in gold plate was on the top of the building. In 695 Empress Wu ordered the erection of an octagonal cast-iron column known as the “Celestial Axis Memorializing the Goodness of the Great Chou Dynasty with its Numberless Areas.” This 20-foot-high column was on a base of cast iron 170 feet in circumference. In 954 the emperor of the Later Zhou Dynasty (951-960) ordered the building of the Great Lion of Zangzhou as a memorial of his military victory over the Liao Tartars. This remarkable object was 20 feet high, 16 feet long, and weighed 40 tons. It was not solid; its walls varied from 2 inches to 8 inches in thickness. This enormous object was made four hundred years before any cast iron was made in Europe, and it was the largest single cast-iron object ever constructed at that time.
Chain Drive. Square-pallet chain pumps were extant in China since the first century C.E. Influenced by the sprockets of common chain pumps, the inventor Zhang Sixun saw the possibilities of replicating a similar design in order to solve the problem of transmitting power in a clock. In 976 he invented the chain drive to solve this problem, and by the tenth century hundreds of thousands of them were in use throughout the empire. In 1090 Zhang’s better-known successor, the great inventor Su Song, attempted to build a gigantic astronomical clock tower, using a main vertical transmission shaft, but failed. As a result, he installed in it the chain drive, which he named “celestial ladder.” Later, Su Song drew an illustration of this chain drive
and printed it in his manuscript New Design for an Astronomical Clock. (It is the oldest illustration in the world of a continual chain drive for power transmission.) Eventually a shorter and tighter chain drive was installed in the clock as a means of removing any slack in the links. The Europeans did not make a real chain drive until Jacques de Vaucanson produced one in 1770 for silk reeling and throwing mills.
Buoyancy Techniques. By the eleventh century the Chinese had developed a technique for recovering weighty items from a river or seabed. Between 1064 and 1067 the renowned pontoon bridge near Puzhou over the great Yellow River was smashed by an unexpected flood. This bridge, which had been built three centuries earlier, was a major crossing of the river. It was composed of floating boats firmly connected together by a huge wrought-iron chain. The ends of the chain were fastened to eight gigantic cast-iron figures in the shape of recumbent oxen put in the sandy beaches on the two banks. When the flood carried away the bridge, the iron oxen were dragged into the river and sank deep underwater. Distressed local administrators made an announcement to solicit suggestions for recovering the iron oxen. A monk, Huaiping, answered this call. Directed by Huaiping, workers loaded two big boats with soil, and divers fastened cables from them to the oxen in the riverbed. Soil was slowly unloaded from the boats, which caused them to rise higher and higher in the water. As a result, buoyancy was created and raised the oxen from the riverbed. Workers then hauled the iron oxen by sailing boats into shallower water toward the shore. This event represents the first recorded attempt in world history to employ buoyancy techniques successfully in an underwater salvage operation.
Astronomical Clock. The Chinese Buddhist monk and mathematician Yixing created the world’s first mechanical clock, which was in fact an astronomical instrument. Completed in 725, the clock was known for its accuracy and was placed in the palace where many officials observed it. In 730 candidates in the imperial examination were required to write an essay on the new astronomical clock. Yixing’s machine was, like water clocks, subject to changes of climate. For example, cold temperatures could freeze the water inside such clocks, and attendants had to keep them warm by placing lit torches nearby. Since mercury does not freeze at any temperature, Zhang Sixun used it instead when he built another clock in 976. Representing a substantial amplification and enhancement of Yixing’s device, Zhang’s clock was much larger and more complicated.
Su Song. Su Song built the largest clock in the world in 1092. It is known in significant detail because his book, New Device for a Mechanical Armillary Sphere and Celestial World, has been preserved. Like the earlier clock by Zhang, Su Song’s device was actually an astronomical clock tower more than thirty feet high. On top of the tower was an enormous bronze astronomical apparatus, with which people could watch the location of stars. A celestial globe within the tower turned in harmonization with this sphere above so the two could continually be contrasted. On the front of the tower was a pagoda
structure of five stories, each having a door through which figures of servants rang chimes and gongs and grasped tablets to show the hours and other special times of the day and night. All of these time indicators were maneuvered by the same huge clock mechanism that concurrently moved the sphere and the globe. Europeans did not develop a similar mechanical clock until the fourteenth century.
Porcelain. A hard, white, translucent ceramic, porce-lain is made by firing pure clay and glazing with variously colored fusible materials. It is burned at a high temperature of 1,300 degrees. (Earthenware or common pottery is made from clay heated in a furnace at temperatures between 500 and 1,000 degrees.) The Chinese invented porcelain as early as the third century; by the tenth century it had reached high levels of artistry. Porcelain production was an extremely well-organized enterprise employing hundreds of thousands of people. While some workers specialized in cleaning the clay, others did the glazes. Large ovens could handle 25,000 pieces of porcelain at a single firing. The typical kiln was constructed on the slope of a hill, and the mild incline of about 15 degrees could help to decrease the speed of flames and thus control the firing. Some kilns were fired with either wood or charcoal. Chimneys were obviously used, along with sophisticated layers of insulation, but-tresses, and clay linings.
Blue-and-White Ware. The attainment of certain colors and effects in porcelain was the consequence of complicated and clever control of the firing conditions of the kilns. Porcelain could be produced either in oxidizing or deoxidizing fires. A variety of metals, used as coloring agents, spread themselves chemically throughout the bodies of the porcelain objects in fairly different ways, relying on whether oxygen was being absorbed or emitted. When the blaze was reduced, it caused porce-lain to emit oxygen, contributing to some of the most beautiful effects. In the Ming era (1368-1644) the Chinese learned how to manufacture the famous blue-and-white ware. As gifts for kings and queens porcelain objects were not popular in Europe until the fifteenth century, and Europeans did not produce porcelain them-selves until three hundred years later.
Economic Lamp. By the fifth century B.C.E. the Chinese frequently used long-lasting asbestos wicks for lamps. The oil-and-wick lamp was actually a cup full of oil with a wick sticking out of it. However, the lamp had one major problem: the heat of the burning wick made much of the oil evaporate before it could be productively burnt. To save oil, the Chinese devised a method by the ninth century to cool the lamp in an effort to prevent evaporation. They invented the economic lamp, which had a reservoir of cold water below the oil and could save one-half the oil used. The economic lamp, normally made of glazed earthenware, was illustrated in Lu Yu’s book Comments from the Hall of Learned Old Era (1190).
Spinning Wheel. The spinning wheel had its origins in China. The Chinese invented the quilling machine in the first century B.C.E. in order to process cotton fibers. Domestication of the silkworm and development of the
MECHANICAL CLOCK
he first mechanical clock in the world was built by the Buddhist monk and mathematician Yixing in 725. A contemporary text described it as follows:
[It] was made in the image of the round heavens and on it were shown the lunar mansions in their order, the equator and degrees of the heavenly circumference. Water, following into scoops, turned a wheel automatically, rotating it one complete revolution in one day and night [24 hours]. Besides this, there were two rings fitted around the celestial sphere outside, having the sun and moon threaded on them, and these were made to move in cir-cling orbit. Each day as the celestial sphere turned one revolution westwards, the sun made its way one degree eastwards, and the moon 13 7/19 degrees eastwards. After 29 rotations and a fraction of a rotation of the celestial sphere, the sun and moon met After it made 365 rotations the sun accomplished its complete circuit.
Source: Robert Temple, The Genius of China: 3,000 Years of Science, Discovery, and Invention (New York: Simon ot Schuster, 1986).
silk industry in China had taken place by the fourteenth century. The inherent strength of silk made it stronger than any other plant fiber known at the time, and from the beginning there was an urgent need for silk-winding machines to deal with the enormously long fibers. (A single continuous strand of silk could run up to several hundred yards and had a tensile strength of 65,000 pounds per square inch.) Spinning wheels began to appear in China by the eleventh century, and these machines were first illustrated in the book Pictures of Tilling and Weaving (1237).
Sources
Derk Bodde, Chinese Thought, Society, and Science: The Intellectual and Social Background of Science and Technology in Pre-Modern China(Honolulu: University of Hawaii Press, 1991).
E-tun Sun and Shiou-chuan Sun, trans., Tien-kung k’ai-wu: Chinese Technology in the Seventeenth Century (University Park: Pennsylvania State University Press, 1966).
Robert Temple, The Genius of China: 3,000 Years of Science, Discovery, and Invention (New York: Simon 6c Schuster, 1986).