梦溪笔谈
The most important nautical innovation of the Song period seems to have been the introduction of the magnetic mariner's compass, which permitted accurate navigation on the open sea regardless of the weather. The magnetized compass needle known in Chinese as the "south-pointing needle" was first described by Shen Kuo in his 1088 "Dream Pool Essays" and first mentioned in active use by sailors in Zhu Yu's 1119 "Pingzhou Table Talks".