A column
Base, shaft (with entasis and flutes) and capital.
The rules it illustrates
Diminution: the taller the column, the less it tapers. 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.
Vignola’s entasis: straight for a third, curved above. 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.
The Corinthian capital. The Corinthian capital is as high as the column is thick; its abacus is one seventh of that height, and the rest is divided in three: the lower leaves, the upper leaves, and the stalks from which the volutes spring.
Mauch’s volute: each turn half the one outside it. Draw the Ionic volute seven eye-diameters high and six wide, with the eye four diameters below the top; lay three turns about centres set out in the eye so that each winding is half as wide as the one outside it and the spiral runs into the top of the eye.
The Composite capital: Ionic volutes on Corinthian leaves. Compose the Roman or Composite capital from two rows of Corinthian leaves round the bell with a full Ionic capital (echinus and four diagonal volutes) above them.
Where it appears in the book
In the chapters The Anatomy of an Order, The Tuscan Order, The Ionic Order, The Corinthian Order, The Composite Order.
The terms it shows
Abacus · Acanthus · Attic base · Echinus · Volute