During the Warring States period, our people made a tool to indicate the direction with magnets, called "Sina". "Sina" means guide.

The shape of Sina is completely different from the current compass. It is made according to the shape of an ancient spoon, much like the spoon we use now.

How did Sina make it? According to expert research, Sina grinds the whole natural magnet into the shape of a spoon, and grinds its S pole into a long handle, so that the center of gravity falls in the middle of the round and smooth bottom.

When Sina is finished, she will make a smooth chassis. When in use, first put the chassis flat, then put Sina in the middle of the chassis, and move its handle by hand to make it rotate. When Sina stopped, its long handle pointed south and its spoon mouth pointed north.

SiNa chassis is made of bronze, have a plenty of a painted board, bronze and lacquerware are very smooth, friction resistance is very small, SiNa rotation is very flexible. This kind of chassis has an inner ring and an outer ring, and the periphery is also engraved with grid lines and characters indicating orientation. Among the unearthed cultural relics, there are such bronze plates and painted wooden plates; There is also a stone carving of the Eastern Han Dynasty, carved on a small square platform with a small spoon. Some people think this is Sina.

Sina is the earliest "compass" in the world. During the Warring States period, some people went to collect jade, afraid of getting lost in the barren hills, and took Sina away.