showed so plainly the mere mechanical structural wants of the roof as to be most unpleasing. Before, however, they could accomplish even this, the side-aisles had to be re-vaulted with pointed arches so as to carry the centre of gravity higher. A half vault was thrown over the gallery as shown in Fig. 1, on the left side of the Woodcut No. 614, and the whole upper structure considerably strengthened. When all this was done they ventured to carry out what was practically, as will be seen from the plan (Woodcut No. 612), and elevation (Woodcut No. 616), a quadripartite vault with an intermediate insertion, which insertion was, however, neither quite a rib, nor quite a compartment of a vault, but something between the two; and in spite of all the ingenuity bestowed upon it in Germany, France, and England, in the 11th and beginning of the 12th centuries, it never produced an entirely satisfactory effect, until at last the pointed arch came to the rescue. It is easy to see from the diagram (Woodcut No. 615) how the introduction of the pointed arch obviated the difficulty. In the first place, supposing the great vault to remain circular, two segments of the same circle, A B, A C, carry the intersecting vault nearly to the height of the transverse one, or it could as easily be carried to the same height as at D. When both were pointed, as at E and F, it was easy to make their relative heights anything the architect chose, without either forcing or introducing any disagreeable curves. By this means the compartments of the vaults of the central nave were made the same width as those of the side-aisles, whatever their span might be, and every compartment or bay was a complete design in itself, without reference to those next to it on either side. The arrangement in elevation of the internal compartments of the nave of this church will be understood from Woodcut No. 616, where it will be seen that the aisles are low, and above them runs a great gallery, a feature common in Italy, but rare in Germany. Its introduction may have arisen either from a desire for increased accommodation, or merely to obtain height, as it is evident that an arch the whole height of the side-aisles and gallery would be singularly narrow and awkward. This was one of those difficulties which were only got over by the introduction of the pointed arch; but which, whenever attempted in the circular style, led to very disagreeable and stilted effects. It may, however, have been suggested by the abutting galleries we find so frequently used in Southern churches. Be this as it may, the two storeys of the aisles fill up the height far more pleasingly than could be done by one, and bring an abutment up to the very springing of the main vault of the nave.