In this paper the author has classified and arranged sensitivity of mechanical precision balances which have been used for thousands of years and that of electric precision balances which have recently been developed, making them correspond to the years reckoned backward from A. D. 2000 taken as the basis, and analyzing the regression equation of the limit line of the relationship between maximum sensitivity and the above-mentioned years, obtained the following results:
On the limit line of maxmum sensitivity lie the majority of precision balances made by people in the range of ancient civilization as well as by those in advanced countries. There is some likelihood that the ancient Orient is the birthplace of the balance. The First Industrial Revolution influenced greatly development of sensitivity of precision balances.
After sensitivity of mechanical precision balances reached their theoretical limit, an electric precision balance making use of various electric phenomena was developed. For measurement of minute mass in future, electric precision balances with higher sensitivity will be developed.
