From Grand Illusions.

This is a working model of a Chinese compass that dates from the 4th century BC. It is believed to be the oldest instrument in the world which is known to be a compass.

The square plate is made of bronze, and the spoon or ladle is made of lodestone. Lodestones are naturally magnetised pieces of the mineral magnetite, and they are naturally occurring magnets.

This type of compass was not used for navigation, rather it was used for semi-magical purposes. The central circle on the bronze plate represents heaven; there are 8 Chinese characters around it for North, North-East, East, etc. Separately marked are the 24 compass points, and around the edge are the 28 lunar mansions.

The handle of the ladle points towards the south, and this device was used for aligning houses and cities harmoniously with the breaths and currents of the earth’s forces, a technique known as geomancy.