coolancientstuff:In 132, Zhang Heng, astronomer, mathematician, scientist, engineer, inventor, geogr
coolancientstuff:In 132, Zhang Heng, astronomer, mathematician, scientist, engineer, inventor, geographer, cartographer, artist, poet, statesman, and literary scholar, presented to the Han court what many historians consider to be his most impressive invention, the first seismoscope. A seismoscope records the motions of Earth’s shaking, but unlike a seismometer, it does not retain a time record of those motions. It was named “earthquake weathervane” (houfeng didongyi 候風地動儀), and it was able to roughly determine the direction (out of eight directions) where the earthquake came from. According to the Book of Later Han (compiled by Fan Ye in the 5th century), his bronze urn-shaped device, with a swinging pendulum inside, was able to detect the direction of an earthquake hundreds of miles/kilometers away. This was essential for the Han government in sending quick aid and relief to regions devastated by this natural disaster. The Book of Later Han records that, on one occasion, Zhang’s device was triggered, though no observer had felt any seismic disturbance; several days later a messenger arrived from the west and reported that an earthquake had occurred in Longxi (modern Gansu Province), the same direction that Zhang’s device had indicated, and thus the court was forced to admit the efficacy of the device.To indicate the direction of a distant earthquake, Zhang’s device dropped a bronze ball from one of eight tubed projections shaped as dragon heads; the ball fell into the mouth of a corresponding metal object shaped as a toad, each representing a direction like the points on a compass rose. His device had eight mobile arms (for all eight directions) connected with cranks having catch mechanisms at the periphery. When tripped, a crank and right angle lever would raise a dragon head and release a ball which had been supported by the lower jaw of the dragon head. His device also included a vertical pin passing through a slot in the crank, a catch device, a pivot on a projection, a sling suspending the pendulum, an attachment for the sling, and a horizontal bar supporting the pendulum. Wang Zhenduo (王振鐸) argued that the technology of the Eastern Han era was sophisticated enough to produce such a device, as evidenced by contemporary levers and cranks used in other devices such as crossbow triggers. -- source link