‹‹‹ Vitr. 3.5.8 | Table of Contents | Vitr. 3.5.10 ›››
9always remembering, that the higher the eye has to reach, the greater is the difficulty it has in piercing the density of the air, its power being diminished as the height increases; of which the result is, a confusion of the image. Hence, to preserve a sensible proportion of parts, if in high situations, or of colossal dimensions, we must modify them accordingly, so that they may appear of the size intended. The under side of the architrave is to be as wide as the upper diameter of the column, at the part under the capital; its upper part equal in width to the lower diameter of the column.
9For the higher that the eye has to climb, the less easily can it make its way through the thicker and thicker mass of air. So it fails when the height is great, its strength is sucked out of it, and it conveys to the mind only a confused estimate of the dimensions. Hence there must always be a corresponding increase in the symmetrical proportions of the members, so that whether the buildings are on unusually lofty sites or are themselves somewhat colossal, the size of the parts may seem in due proportion. The depth of the architrave on its under side just above the capital, is to be equivalent to the thickness of the top of the column just under the capital, and on its uppermost side equivalent to the foot of the shaft.