My own interests date back to childhood when, at my grandmother’s house, aged four or five, left alone in a living-room-plus-library for a nap, I found a fascinating book of architecture filled with floor plans and architectural drawings—nothing like children’s books—and I fell into a life-long fascination. Later yet once I read a book on the arch—and its absence, for instance—in pre-Columbian American architecture. And then, while in Germany as a soldier, I spent my free time traveling all over Europe to haunt the great cathedrals. The Gothics were my favorites—and these feature that wondrous innovation, the flying buttress.
This drawing of a buttress at the Reims Cathedral is from an album of drawings by Villard de Honnecourt from the period 1230 - 35 obtained from Wikipedia here. This flying buttress has two wings, you might say. The interior of the cathedral is to the right; the buttress is outside under the open sky.This elegant form came about because architects of that period (roughly the twelfth and thirteenth centuries) wished to build open cathedrals, the interior entirely hollow; “soaring” is often the word applied to capture the feeling we have as we look up into the dark immensities above. To get the open space, the ceiling could no longer be held up by a forest of massive interior columns. But, as a consequence, the weight of the ceiling used to cause the outer walls to push, to cave outward; if this was left uncorrected, the building could collapse. Two possibilities existed to correct this: to build very thick walls with very narrow or no openings at all. But the architects wanted lots of light to enter from without. Therefore they piled masses of stone on the outside of the walls to buttress them—not all the way up to where the windows were, but thickly at the bottom.
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Notre Dame picture courtesy of Andy Hochhalter here.