衡石量书

Explanation: "Records of Emperor of the century": "the world of things, not all depends on the size, from rock to balance the amount of books, day and night there was not was not in the rest." Notes on ancient instruments with bamboo wood to stone to calculate the value the weight of the instrument, as used to describe the monarchy diligent national policy. Also as "value-stone process book." 　　Source: "Records of Emperor of the century" the world of things, not all depends on the size, from rock to balance the amount of books, day and night there was not was not in the rest. "