0078 – Zhang Heng – bio

Born in 78 in the province of Yuzhou (now known as Henan) of the Han dynasty in China, Zhang Heng was known as a scientist, mathematician, engineer, astronomer, painter and more. He became the chief astrologer to the emperor, An-Ti. He created a rotating globe that was a map of the sky and constellations. He eventually added dripping water and a system of gears to power turning the globe by one revolution each year.

He developed an expertise in astronomy, drawing detailed maps of stars and constellations that allowed him to make corrections to the calendar currently being used. He improved upon the estimation of the value of Pi by using the square root of ten. He invented the first seismograph to measure earthquakes. He is credited with inventing the first Chinese odometer, although Archimedes did the same thing several hundred years earlier in Greece.

Zhang Heng was also a prolific writer and was considered to be one of the best painters of his time.

-1900 – pi
-0287 Archimedes
-0276 Eratosthenes
-0200 – Chang Tshang
-0078 Jing Fang

0083 – Ptolemy

0220 – Liu Hui
0499 – Aryabhata
0683 – Yi Xing
1020 – Su Song
1231 – Guo Shoujing

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