bk. n. Ch. vn. NOHMANDY. 517 381. Diagram of Vaulting. 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 gallerv, as shown in Fig. 1, on the left side of the Woodcut No. 380, and the Avhole upper structure considerably strength- ened. When all this was done they ventured to carry out what was practically, as will be seen from the plan (Woodcut No. 378), and elevation (Woodcut No. 382), a quadripartite vault with an intermediate insertion, which insertion was, however, neither quite a rib, nor quite a compart- ment 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 be- ginning 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 diagrani (Woodcut No. 381) how the introduction of the ])ointed arch obviated the diffi- culty. In the first place, sup- posing the great vault to remain circular, two segments of the same circle, a d, a c, carry the inter- secting 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 intro- ducing any disagreeable curves. o>i2 Elevation of Coiiipartnient of Nave of St. Stephen, Caen. (From Pugiu.) By tills means the comi^artments
