When did the ancient steelyard in China begin?

When the ancient steelyard in China began is still inconclusive. It is improved and invented on the basis of balance scale.

In the Western Zhou Dynasty, at the latest in the Spring and Autumn Period and the Warring States Period, China already had a "scale". According to archaeological findings, "weight" is a kind of weight, and it is judged as the principle of "balance". The lifting button is in the middle of the balance beam, and there are two scales at both ends. One end puts the measured object and the other end adds "weight", and the weight is equal to the weight of the object.

The steelyard based on lever principle appeared a little later than the balance. The two pieces of "Wang Tongheng" collected by China History Museum are scales of Chu State in the Warring States Period, which are unequal-arm scales and belong to the transitional scales from scales to lifting scales.

Archaeology can confirm that the real steelyard appeared in the Eastern Han Dynasty of the Three Kingdoms.