Final answer:
Early sailors used lodestone as an early navigational compass to find direction by its natural ability to align north-south when suspended or floating.
Step-by-step explanation:
In the days of early seafaring, sailors used lodestone, a magnetised form of iron-oxide, to find direction. The lodestone would naturally orient itself in a north-south direction when suspended freely on a string or floating on water. This property enabled sailors to use lodestone as an early form of a navigational compass, which was crucial for maritime exploration before the advent of more sophisticated instruments like the magnetic compass and the sextant.
While sailors used tools like the cross-staff and later the backstaff to measure the elevation angle of celestial bodies for latitude estimation, the lodestone provided a simple yet effective means for them to maintain a sense of direction out at sea, which was especially vital when no landmarks were in sight.