The Pillars of the Earth - Ken Follett [393]
There was more to it. In between the ribs, instead of the usual web of mortar-and-rubble, this builder had put cut stones, as in a wall. Being stronger, the layer of stones could probably be thinner, and therefore lighter, Jack realized.
As he stared up, craning his neck until it ached, he understood a further remarkable feature of this combination. Two pointed arches of different widths could be made to reach the same height, merely by adjusting the curve of the arch. This gave the bay a more regular look. It could not be done with round arches, of course: the height of a semicircular arch was always half its width, so a wide one had to be higher than a narrow one. That meant that in a rectangular bay, the narrow arches had to spring from a point higher up the wall than the springing of the wide ones, so that their tops would be at the same level and the ceiling would be even. The result was always lopsided. This problem had now vanished.
Jack lowered his head and gave his neck a rest. He felt as jubilant as if he had just been crowned king. This, he thought, was how he would build his cathedral.
He looked into the main body of the church. The nave itself was clearly quite old, although relatively long and wide: it had been built many years ago, by someone other than the current master, and it was quite conventional. But then, at the crossing, there seemed to be steps down—no doubt leading to the crypt and the royal tombs—and steps up to the chancel. It looked as if the chancel were floating a little way above the ground. The structure was obscured, from this angle, by dazzling sunlight coming through the east windows, so much that Jack supposed the walls must be unfinished, and the sun shining through the gaps.
He walked along the south aisle to the crossing. As he got nearer to the chancel he sensed that something quite remarkable was ahead of him. There was, indeed, sunlight pouring in, but the vault appeared to be complete and there were no gaps in the walls. When Jack stepped out of the aisle into the crossing he saw that the sun was streaming in through rows of tall windows, some of them made of colored glass, and all this sunshine seemed to fill the vast empty vessel of the church with warmth and light. Jack could not understand how they had got so much window area: there seemed to be more window than wall. He was awestruck. How had this been done, if not by magic?
He felt a frisson of superstitious dread as he mounted the steps that led up to the chancel. He stopped at the top of the stair and peered into the confusion of shafts of colored light and stone that was ahead of him. Slowly the realization came over him that he had seen something like this before, but in his imagination. This was the church he had dreamed of building, with its vast windows and surging vaults, a structure of light and air that seemed held up by enchantment.
A moment later he saw it differently. Everything fell into place quite suddenly, and in a lightning flash of revelation, Jack saw what Abbot Suger and his builder had done.
The principle of rib-vaulting was that a ceiling was made of a few strong ribs, with the gaps between the ribs filled in with light material. They had applied that principle to the whole building. The wall of the chancel consisted of a few strong piers joined by windows. The arcade separating the chancel from its side aisles was not a wall but a row of piers joined by pointed arches, leaving wide spaces through which the light from the windows could fall into the middle of the church. The aisle itself was divided in two by a row of thin columns.
Pointed arches and rib-vaulting had been combined here, as they had in the narthex, but