This ware is only second in importance to the Ju yao, and its exact nature is scarcely less speculative. The name, which means "official" or "Imperial" ware, seems to have been first applied to the porcelains made for Imperial use at the Northern Sung capital, the modern K´ai-fêng Fu, in Honan. The factory was established at the command of the Emperor Hui Tsung in the Chêng Ho period (1111-1117), according to the earliest[113] or in the preceding Ta Kuan period (1107-1110), according to a later[114] account. Its career, however, was interrupted by the flight of the Sung Court south of the Yangtze in 1127, though it is probable that a number of the potters followed the Court. At any rate, the traditions of the original factory were continued at the new capital, Hang Chou, by an official named Shao Ch´êng-shang, who set up kilns in the Imperial precincts, in the department called _Hsiu net ssŭ_. Another writer locates this factory under the Phœnix Hill. Shortly afterwards a new pottery was started "below the suburban altar" at Hang Chou, which copied the forms of the older Kuan ware, but without equalling its quality. We have then no fewer than three different makes all included in the name of Kuan yao, all following one tradition but differing, as we shall see, in material and quality. The first is the K´ai-fêng Fu variety. The earlier writers in the _Cho kêng lu_ and _Ko ku yao lun_ make no attempt to differentiate[115] this porcelain from the later Kuan yao, but we find in a sixteenth-century collection of miscellanies, the _Liu ch´ing jih cha_, the following scrap of information: that "specimens (of the K´ai-fêng ware) with streaky colour, white on the upper part and thin as paper, were inferior to Ju ware"; and the more modern _T´ao lu_ informs us that the K´ai-fêng Kuan ware was made of fine unctuous material with thin body, the colour of the glaze being _ch´ing_ (blue or green) with a tinge of pale red (_fên hung_) and of varying depth of tone. It is further stated that in the Ta Kuan period moon white or _clair de lune_ (_yüeh pai_), pale green or blue (_fên ch´ing_) and deep green (_ta lü_) glazes were esteemed, whereas in the Chêng Ho period only the _ch´ing_ colour in varying depth of tone was used. Moreover, the glaze had "crab's claw crackle," and the vessels had a "red-brown mouth and iron foot." The latter phrase (explained below) is not consistent with the account in the _Liu ch´ing jih cha_, "white on the upper part," which certainly implies a light-coloured clay, but I confess that I have little confidence in the subtle distinctions of the _T´ao lu_ in this passage. They are mere assertions, without any reasons given, and it is not difficult to find a source from which they may in part, at least, have been derived, and which in itself guarantees no such differentiation.[116] It is likely enough that the K´ai-fêng ware differed in body from the red ware of Hang Chou, but it is not likely to