The second period, covering roughly the second half of the seventeenth century, is noted for several great works on historical geography, produced by that galaxy of scholars which Hsü Ch'ien-hsüeh [q. v.], the retired Chinese political leader, brought together for the purpose of editing the Ta-Ch'ing i-t'ung chih (Comprehensive Geography of the Empire, see I, p. 311). These scholars included Yen Jo-chü, Ku Tsu-yü, Hu Wei [qq. v.] and Huang I (see I, p. 335)—all of whom made important contributions to the study of the Shui-ching chu. The last two, however, Huang I and Hu Wei, attempted a further improvement of the text by making use of contemporary geographical knowledge and by working out a series of maps illustrating the course of the rivers. The works of Huang I are only partially preserved in Hu Wei's Yü-kung chui-chih (see I, p. 335) which, with its forty-seven maps, became the most important key to the study of the main waterways in their historical vicissitudes.
The third period (1725–1794) may be described as the era of consummation in the critical study of the Shui-ching chu. Three men stood out pre-eminently in this period: Ch'üan Tsu-wang (1705–1755), Chao I-ch'ing (1711–1764) and Tai Chên (1724–1777). Building on the same cumulative achievements of their predecessors, and applying the same critical methods of research, these three scholars arrived at practically the same solutions of the numerous problems left over from the preceding period. The fact that their methods and results were so impressively similar gave rise, oddly enough, to a suspicion, lasting a century and a half, that one or the other of them had been guilty of plagiarism.
Tai Chên, the youngest of the trio, published at about the same time two editions of his Shui-ching chu. One, printed from movable type by the Palace Press, appeared in 1775; a private edition, printed from wood blocks, came out either in the same year or early in 1776. The Palace edition follows the traditional arrangement in forty chapters and has fairly detailed editorial notes. The private edition abolishes the chapter divisions, and rearranges the waterways according to their geographical proximity, but it contains only the text as emended and rearranged by Tai, without a single editorial note.
The Palace edition was based on the text which Tai Chên had prepared for the Imperial Manuscript Library (Ssŭ-k'u ch'üan-shu, see I, p. 121). In preparing this text, he had the rare privilege of using for collation a text contained in the great manuscript encyclopaedia, Yung-lo ta-tien (see I, p. 198), which was first transcribed in the year 1403–08 and re-copied in the sixteenth century. This was probably the only important text that was not known to his senior fellow-workers, Ch'üan and Chao.
Two recently published letters by Grand Secretary Yü Min-chung [q. v.] indicate that, after Tai had submitted his completed text in the summer of 1774, one of the associate directors of the Ssŭ-k'u ch'üan-shu raised some strong objections to it, thus making it necessary for a "compromise arrangement" to be made before it was finally accepted for transcription into the Imperial Library. Hasty conjectures (see II, p. 696) have been made as to the significance of this dispute. My own conjecture is that the objection was perhaps chiefly to Tai's frank opinion of the state of corruption of the Yung-lo text; to his desire to make known that it was his own life-long work which was being used; and that the "compromise arrangement" ordered by the Imperial directors most probably took the form which it now has in
