Compass

History of compass

The first compasses in ancient Han dynasty China were made of lodestone, a naturally magnetized ore of iron.

The compass was later used for navigation during the Song Dynasty of the 11th century.

Later compasses were made of iron needles, magnetized by striking them with a lodestone.

Dry compasses began to appear around 1300 in Medieval Europe. This was supplanted in the early 20th century by the liquid-filled magnetic compass.

Which famous professor from Denmark saw that the magnetic needle of a compass changes direction when it is near a cable run by electric current?

…and a little help: His first and middle name was the same as the famous story teller from Denmark Hans Christian Andersen.

Come on, his last name is all we want from you!