known in Persia by the 6th century AD. Eric Broudy asserts there is virtually no evidence of its use in Europe until the 17th century, while the button drawloom was allegedly invented by Jean le Calabrais in the 15th century. Mary Carolyn Beaudry disagrees, stating that it was used in the medieval Italian silk industry. Drilling rig: The technique of percussion drilling for oil and gas originated during the ancient Chinese Han Dynasty in 500 BC, when percussion drilling ("churn drilling") was used to extract natural gas in Sichuan province. Iron bits were fastened to long bamboo poles, which were centered within a bamboo derrick. The poles were repeatedly hoisted, using cables woven from bamboo fiber. With the assistance of levers, very heavy bits could be raised, of sufficient weight to percussively bore through rock when repeatedly dropped. Han dynasty oil wells were around 10m deep; by the 10th century, depths of 100 meters could be achieved. By the 16th century, Chinese oil prospectors were using percussion drilling to create wells over 2000 feet deep. A modernized variant of the technique was used by American businessman Edwin Drake to drill Pennsylvania's first oil well in 1859, using small steam engines to power the drilling process. E Escapement, hydraulic-powered (use in clock tower): The escapement mechanism was first described for a mechanical washstand by the Greek Philon of Byzantium who also indicated that it was already used for clocks. An escapement mechanism for clockworks was later developed by the Buddhist monk, court astronomer, mathematician and engineer Yi Xing (683–727) of the Tang Dynasty (618–907) for his water-powered celestial globe in the tradition of the Han dynasty polymath and inventor Zhang Heng (78–139), and could be found in later Chinese clockworks such as the clock towers developed by the military engineer Zhang Sixun (fl. late 10th century) and polymath inventor Su Song (1020–1101). Yi Xing's escapement allowed for a bell to be rung automatically every hour, and a drum beaten automatically every quarter-hour, essentially a striking clock. Unlike the modern escapement which employs a suspended oscillating pendulum resting and releasing its hooks on a small rotating gear wheel, the early Chinese escapement employed the use of gravity and hydraulics. In Su Song's clock tower, scoop containers fixed to the spokes of a vertical waterwheel (which acted like a gear wheel) would be filled one by one with siphoned water from a clepsydra