 The Chinese polymath Shen Kuo (1031–1095) of the Song Dynasty (960–1279) was the first to accurately describe both magnetic declination (in discerning true north) and the magnetic needle compass in his "Dream Pool Essays" of 1088, while the Song dynasty writer Zhu Yu (fl.12th century) was the first to mention use of the compass specifically for navigation at sea in his book published in 1119.Even before this, however, the "Wujing Zongyao" military manuscript compiled by 1044 described a thermoremanence compass of heated iron or steel shaped as a fish and placed in a bowl of water which produced a weak magnetic force via remanence and induction; the "Wujing Zongyao" recorded that it was used as a pathfinder along with the mechanical south-pointing chariot.