By 800 AD, floating iron compasses were common on Chinese ships and led to their bold, open-ocean exploration as far as India. The compass placed Chinese exploration and ship navigation centuries ahead of European and Arab counterparts.
Adelard of Bath in 1117 was the first European to note that the lodestone pointed in a certain direction.
Many others then wrote about it, most notably Petrus Peregrinus in 1269 in a text that is one of the finest contributions to physics.
Among Arabic sources, the earliest descriptions of the magnetic compass occur in the thirteenth century. Muhammad al-Awfi writes of a fish-shaped magnetic compass in 1232.
In 1282 Bailak al-Qabajagi described how in 1242 he had witnessed the use of a floating compass needle, and added that the captain who sailed the Indian seas employed a floating iron leaf shaped like fish.
The lateness of Arabic references suggests that the compass may have reached the West by an inland route.
Magnetic compass in history
