a piece with those vaulted undercrofts or substructures which are so common under the principal buildings of monasteries and other houses, and which are constantly mistaken for cloisters, dormitories, and what not.[51] There cannot be a better example than the lower stage of our own Bishop's palace. I need hardly say that, when this substructure and the staircase were made, the Chapter-house was already designed; for both staircase and substructure are simply buildings subordinate to the Chapter-house. Yet there must be a certain difference of date between the two. The staircase must be a little later than the church itself, for it is manifestly built up against the buttresses of the north transept, and, while the church has only lancet windows, the staircase has some of the best examples of the earliest form of Geometrical tracery. The Chapter-house itself again has Geometrical tracery of a later type, and the details throughout are more advanced. It appears from Professor Willis's account that in 1286 the Chapter determined to finish a certain new structure which had been long before begun, and which urgently needed to be finished. This, as the Professor says, can be no other than the Chapter-house. In 1286, then, the staircase and substructure were already finished, but the works were at a standstill, and the Chapter-house itself had not yet been begun. The result of these debates of the Chapter was the carrying out of the Chapter-house. The general design had no doubt been planned long before, and it was now carried out according to that original design, but, as might be expected, with all the changes in detail, whether we look on them as improvements or not, which had come into fashion since the work began.[52]