In what fields did the ancient Chinese make Sina?

This issue is controversial, or modern people have problems with their understanding of ancient books. For the recovery of Sina, it is unreliable.

This recovery model can indicate north and south, because tungsten steel is used for magnetization. The material of tungsten steel was unimaginable in ancient times. The most reasonable explanation for Sina in ancient books is Sina, which refers to the Big Dipper. Now the Chinese History Museum no longer shows this Sina model. Afraid of being laughed at by the whole world.