How do you replicate an ancient item that has been no surviving remnants or illustrations to work from? Historical descriptions and texts have given clues to replicate an ancient seismoscope invented by Zhang Heng.
Zhang Heng lived in China during the Han dynasty, and history remembers him as a scholar in many fields. He dabbled in astronomy, mathematics, science, engineering, cartography and poetry, among other fields of study and artistic pursuits. He served as a government official for much of his adult life, and was invited to the imperial court in his mid-30s by Emperor An in honor of his skills as a mathematician.
He worked on calculating pi, mapped stars, and in tandem with his academic career, was an inventor. He improved the accuracy of inflow clepsydra -- a type of water clock that measures time by the flow of liquid -- and is credited with creating the first water-powered armillary sphere (a dynamic model that illustrates the movement of celestial objects). But Zhang Heng is most famed for inventing the world's first seismoscope.
In 2005, a group of seismologists and archaeologists from the Chinese Academy of Sciences announced they had created a proven, functioning replica. Read more about Zhang Heng and his invention at Engadget.
Image Credit: [State Post Bureau of the People's Republic of China via Wikimedia Commons](http://jeff560.tripod.com/stamps.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2561547)
Replica of an ancient Chinese Seismoscope.
Image Credit: Kowloonese via Wikimedia Commons