  These activities were not invented by the fang shi. The Han shu Bibliographic Treatise also provides evidence of fang activity through the titles of lost books. Other evidence comes from late Warring States and Han texts such as the Lü Shi chunqiu and Huainanzi. The Huainanzi contains several chapters of astronomical interest (Major 1993). One passage describes the technical interests of the sage emperor Yu, who ordered his officials to measure the distances to the ends of the earth by pacing the distance to the eastern, western, northern and southern extremities of the earth (Huainanzi 4, 56). The exact numbers given are problematic to say the least, but the point is that the sage rulers of antiquity, in legendary accounts, interested themselves in the physical observation of the earth.