How did sea captains use magnets long ago?

Sea captains have used magnets for navigation since the 12th century. Before the invention of the compass, sea captains used lodestones, which are naturally occurring magnets, to determine direction. Lodestones were placed in a bowl of water and allowed to float freely. The end of the lodestone that pointed to the north was marked, and this was used as a reference point for navigation.

In the 13th century, the magnetic compass was invented. This device used a magnetized needle that was suspended in a box. The needle would point to the north, and this was used to determine the direction of travel. The magnetic compass was a much more accurate way of determining direction than the lodestone, and it quickly became an essential tool for sea captains.

The magnetic compass is still used today, and it is one of the most important navigational instruments used by sea captains.