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Shen Kuo or Shen Kua (1031–1095) was a polymath Chinese scientist and statesman of the Song Dynasty. He excelled in many fields of study and statecraft, imcluding; mathematician, astronomer, geologist, zoologist, encyclopedist, poet and diplomat, among many others.
In his Dream Pool Essays of 1088, Shen was the first to describe the magnetic needle compass, which would be used for navigation. Kuo also discovered the concept of true north in terms of magnetic declination towards the north pole. Alongside his colleague Wei Pu, Shen accurately mapped the orbital paths of the moon and the planets, in an intensive five-year project that rivaled the later work of the Danish astronomer Tycho Brahe. To aid his work in astronomy, Shen Kuo made improved designs of the armillary sphere, gnomon, sighting tube, and invented a new type of inflow clepsydra clock.