Divide the inside of a dome into coffers that shrink in step with the meridians as they rise, so that their perspective deepens the dome and draws the eye to the light of the lantern.
Rules · Entablatures · Spacing · Ornament
Triglyphs over every column, and square metopes
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
Greek builders put the corner triglyphs at the very corner of the frieze, which forces the last metope to widen or the corner columns to be moved inward (“corner contraction”). Vitruvius and the Renaissance placed a half-metope at the corner instead and kept the triglyph centred on the column. This “Doric corner conflict” is one of the classic puzzles of architecture.
Related rules
Edge the beds before the portico with box, clip box into figures of animals set facing one another, and in the garden beyond cut it into many shapes, even into the letters of the owner’s name.
Give the villa garden porticoes for sun and for shade, grottoes made in imitation of nature with tufa and shells, evergreens planted in straight rows at equal distances, and hedges of box; set vines on columns over the walks.
Lay the ideal garden out on a circular plan in concentric rings, woods outside, then meadows and orchards, then gardens of knots and clipped evergreens divided by walks, with water and the fountain of the goddess at the centre.
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)
To end the frieze with a triglyph at the corner and keep every metope square, move the corner column inward: make the last intercolumniation narrower than the others by the amount the corner triglyph is displaced.
contraction c = e − t⁄2; Parthenon: 4.29 m normal, 3.68 m at the corners (c ≈ 0.61 m)
Cite this page Chris Paton, “Triglyphs over every column, and square metopes”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/doric-triglyph-rhythm. Text, drawings and models licensed under CC BY-NC 4.0.