All these objections were obviated in the three bays of the choir at Ely, which were rebuilt by Walsingham at the same time as the octagon. Here the triforium and clerestory are equal; but the upper window is so spread out, and so much is made of it, that it looks equal to the compartment below. The pier arch below is also subdued to less than half the whole height, so as to give value to the upper division. These proportions are derived from the very beautiful Early English presbytery beyond; but they are here used with such exquisite taste and such singular beauty of detail that there is perhaps no single portion of any Gothic building in the world which can vie with this part of the choir of Ely for poetry of design or beauty of detail. The perfection of proportion, as of many other things, was reached in Westminster Abbey (1245-1269). Here the whole height is divided into two equal parts, and the upper subdivided into three, of which one is allotted to the triforium, and two to the clerestory. It is true this involves the necessity of springing the vault from a point half way down the clerestory windows, and thus the lines of the severeys do not accord quite with those of the lights; but at best it is a choice of difficulties, and the happy medium seems to have been reached here more successfully than elsewhere. The proportion of the width of a bay to its height is here also most pleasing; it is as 1 to 5½.[105] Sometimes, as at Exeter, it sinks as low as 1 in 3, but the whole effect of the building is very much destroyed by the change. Shortly after this, as in the choir at Lichfield (1250-1325) or at Exeter (1308-1369), the mania for the display of painted glass upset all these arrangements—generally at the expense of the triforium. This feature was never entirely omitted, nor was it ever glazed internally, as was frequently the case on the Continent; but it was reduced to the most insignificant proportions—sometimes not pierced—and, with the wider spacing just alluded to, deprived the English side screen of much of that vigour and beauty which characterised its earlier examples. WINDOW TRACERY.