CONSTRUCTION XIII. THE ROOF 189

vaulting requires its great array of external buttress, not so much from any peculiar boldness in its own forms, as from the greater comparative thinness and height of the walls, and more determined throwing of the whole weight of the roof on particular points. Now the connection of the interior framework (or true roof) with the buttress, at such points, is not visible to the spectators from without; but the relation of the roof mask to the top of the wall which it protects or from which it springs, is perfectly visible; and it is a point of so great importance in the effect of the building, that it will be well to make it a subject of distinct consideration in the following Chapter.

[Version 0.04: March 2008]