1. The earliest scale: the most primitive scale in the world. Physical evidence (Shi Zhong) was found in the Indus civilization site in Pakistan today (about 2400- 1800 BC), with a history of three or four thousand years.
2. China's Scale: In China, in the middle and late Spring and Autumn Period, Chu had made a small scale-wooden scale. The copper ring is right, used to address the gold currency. A complete set of abstinence rights consists of ten pieces, generally increasing in multiples, that is, one baht, two baht, three baht, six baht, twelve baht, one or two, two or two, four or two, eight or two, and one catty.
3. Modern Scale: The Chinese History Museum has a bronze balance bar during the Warring States Period. This scale is different from the balance and the later balance bar, but similar to the unequal arm balance. Through the process of gradual evolution, the heavy arm of the balance bar becomes shorter and the force arm becomes longer, and it has become a scale still in use in modern times.
4. Roman Scale: The steelyard was introduced to the west by the Ministry of Nomads before the birth of Jesus, and was named Roman Scale. This scale is recorded in the works of many Latin writers. Roman scales have different arms, that is to say, the scales at the object end are short and fixed in length. When weighing a heavy object, move the scale hammer at the other end of the scale rod until the scale rod reaches a horizontal state.