Rules · Entablatures · Spacing · Modules
Keep every triglyph centred over a column and every intercolumniation equal, and finish the frieze at the corner with a half-metope half a module wide.
corner semi-metope = ½ M (Vitruvius); equal intercolumniations throughout
Vitruvius presents his modular Doric temple as the cure for the corner problem: by placing “semimetopes” at the outer corners he keeps the rules of the triglyph over the axis and of equal spacing, sacrificing only the Greek rule that the frieze should turn the corner on a triglyph.
This became the standard Roman and Renaissance practice, followed by Vignola and Palladio. To Greek eyes the frieze would have looked unfinished at the corner; to Roman eyes the regularity of the colonnade mattered more. The difference is a small, telling example of two attitudes to rule.
A Doric frieze cannot obey all three of its rules at a corner: triglyphs over the column axes, a triglyph turning the corner, and metopes as broad as they are high. One of them must give way.
displacement of the corner triglyph = e − t⁄2 (e = half-depth of the architrave, t = triglyph width)
Columns may be spaced 1½ diameters apart (pycnostyle), 2 (systyle), 2¼ (eustyle), 3 (diastyle) or more (araeostyle). The eustyle, with a wider central bay of 3 diameters, is the best for use and beauty.
clear space = 1½ · 2 · 2¼ · 3 · >3 D
In a peripteral temple the flanks have twice as many intercolumniations as the front: six columns in front means eleven along each side, counting the corner columns twice.
side columns = 2n − 1 (Vitruvius) · 2n + 1 (Greek practice)
Divide the front of a Doric temple into modules; the column’s thickness is two modules, its height with the capital fourteen, the capital one, the architrave one, and the triglyphs one and a half high and one wide.
M = ½ D; column = 14 M; capital = 1 M; architrave = 1 M; triglyph = 1 × 1½ M; metope = 1½ × 1½ M
Set a triglyph over the axis of every column and over the middle of every intercolumniation (or two, in a wider bay); make the metopes between them as wide as they are high.
axis spacing = n × (triglyph + metope) = n × 2½ M
An order consists of a column (base, shaft and capital) carrying an entablature (architrave, frieze and cornice), optionally raised on a pedestal (plinth, die and cap). Each part is proportioned to the lower diameter of the column.
order = [pedestal] + column(base, shaft, capital) + entablature(architrave, frieze, cornice)
Cite this page Chris Paton, “Vitruvius’s half-metope”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/vitruvius-semimetope. Text, drawings and models licensed under CC BY-NC 4.0.