In a row of arches the thrusts of neighbouring arches cancel over each intermediate pier, which may therefore be slender; at the ends of the row nothing balances them, so the outermost piers must be made wider or buttressed.
Rules · Theory · Columns · Walls
The column is the chief ornament
In all architecture the principal ornament is the column: a part of the wall left standing and pierced through.
For Alberti a colonnade is a wall opened up in several places; an arcade should therefore rest on square piers, since a round column under an arch is a contradiction. Brunelleschi’s arcades on columns broke that rule, and Alberti’s own buildings use piers and pilasters.
Related rules
Give the flight of steps before a temple an odd number, so that one who starts with the right foot will also set the right foot first on the top.
Every building must satisfy three demands at once: it must stand up (firmitas), serve its purpose (utilitas), and give pleasure to the eye (venustas).
architecture = firmitas + utilitas + venustas
A column is narrower at the top than at the bottom, but the taller the column the less it should be diminished, because distance already makes its top look smaller.
upper Ø : lower Ø = 5⁄6 (≤15 ft) · 11⁄13 (15–20 ft) · 6⁄7 (20–30 ft) · 13⁄15 (30–40 ft) · 7⁄8 (40–50 ft)
Keep the lowest third of the shaft cylindrical; above it, reduce the radius along a curve found by dividing a quarter-circle and the upper two-thirds of the shaft into the same number of equal parts.
r(k) = R · cos(α·k), cos α = r_top ⁄ R, k = 0…1 over the upper ⅔
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
Cite this page Chris Paton, “The column is the chief ornament”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/alberti-column-ornament. Text, drawings and models licensed under CC BY-NC 4.0.