They figured out that some of the metal coming out of the ground was naturally magnetic, and so they fashioned this magnetized metal into this kind of ladle-looking thing, put it on a brass plate and then it would point north.
Descobriram que parte do metal que saía do solo era naturalmente magnética. Transformaram esse metal magnetizado numa espécie de concha, que puseram sobre uma placa de latão e apontava para o Norte.