Science and Technology of The Song Dynasty - Wind Power

Wind Power

The effect of wind power was appreciated in China long before the introduction of the windmill during the Song period. It is uncertain when the ancient Chinese used their very first inflatable bellows as wind-blowing machines for kilns and furnaces. They existed perhaps as far back as the Shang Dynasty (1600 BCE–1050 BCE), due to the intricate bronze casting technology of the period. They were certainly used since the advent of the blast furnace in China from the 6th century BCE onwards, since cast iron farm tools and weapons were widespread by the 5th century BCE. In 31 the Han Dynasty governmental prefect and engineer Du Shi (d. 38) employed the use of horizontal waterwheels and a complex mechanical gear system to operate the large bellows that heated the blast furnace in smelting cast iron. Bellows continued in use for purposes of metallurgy, but other sources of wind power were discovered and harnessed. The Han Dynasty artisan Ding Huan (fl. 180) not only pioneered the invention of the cardan suspension, but also the rotary fan, which could be used as a simple air conditioner. This employed seven wheel each about 3 m (10 ft) in diameter and manually powered, but by the Tang Dynasty (618–907) palaces featured water-powered rotary fans for air conditioning, and in the Song Dynasty, states Needham, "the refrigerant effects of artificial draught seem to have been appreciated ever more widely." There was also an intricate Chinese rotary fan winnowing machine depicted in Wang Zhen's agricultural treatise of the Nong Shu of 1313 (although the earliest depiction of a winnowing machine was from a Han Dynasty tomb model dated from the 2nd century BCE to the 2nd century). After these innovations, the windmill was finally introduced to China in the early 13th century via the Jin Dynasty in northern China, during the late Song Dynasty.

The Persian scholar Ali ibn Sahl Rabban al-Tabari wrote c. 850 that the earlier Caliph Umar ibn al-Khattab was murdered in 644 by the technician Abu Lu'lu'a, who claimed to construct mills driven by the power of wind. More reliable than this account were the windmills of the Banu Musa brothers (850 to 870), while there are also several authors confirming the windmills of Sistan (Iran), written of by Abu Ishaq al-Istakhri and Abu al-Qasim ibn Hauqal. The northern Chinese under the rule of the Jurchen Jin Dynasty became acquainted with the windmills of the Islamic world in the early 13th century. This is seen in an account of the Shu Zhai Lao Xue Cong Tan (Collected Talks of the Learned Old Man of the Shu Studio), written by Sheng Ruozi. It read:

In the collection of the private works of the 'Placid Retired Scholar' (Zhan Ran Ju Shi), there are ten poems on Hechong Fu. One of these describes the scenery of that place and says that 'the stored wheat is milled by the rushing wind and the rice is pounded fresh by hanging pestles. The westerners (i.e. Turks) there use windmills (feng mo) just as the people of the south (i.e. Southern Song Dynasty) use watermills (shui mo). And when they pound they have the pesltes hanging vertically'.

Here Sheng Ruozi quotes a written selection about windmills from the 'Placid Retired Scholar', who is actually Yelü Chucai (1190–1244), a prominent Jin and Yuan statesman (after the Jin fell in 1234 to the Mongols). The passage refers to Yelü's journey to Turkestan (modern Xinjiang) in 1219, and Hechong Fu is actually Samarkand (in modern Uzbekistan). Afterwards, the Chinese applied the 'fore-and-aft' sail riggings of typical Chinese junk ships to horizontal windmills. These windmills were used to operate the square-pallet chain pumps used in Chinese irrigation since the ancient Han Dynasty. Windmills of this nature were still in use during modern times in Tianjin and along the Yangtze River. The first European to view Chinese windmills was Jan Nieuhoff, who spotted them in Jiangsu while traveling along the Grand Canal in 1656, as part of the Dutch embassy to Beijing. The first European windmills written of were those of Dean Herbert of East Anglia in 1191, who competed with the mills of the Abbey of Bury St Edmunds.

After the windmill, wind power applications in other devices and even vehicles were found in China. There was the 'sailing carriage' that appeared by at least the Ming Dynasty in the 16th century (although it could have been known beforehand). European travelers to China in the late 16th century were surprised to find large single-wheel passenger and cargo wheelbarrows not only pulled by mule or horse, but also mounted with ship-like masts and sails to help push them along by the wind.