What is a trochilus?

A trochilus, more often called a scotia in English, is a deep concave moulding in the base of a column. In the classic Attic base the scotia sits between two convex mouldings, the tori. The strong contrast between convex and concave creates a deep line of shadow that gives the foot of the column a bold, sculptural look.

Origin of the name

The Roman architect Vitruvius uses the word scotia and notes that the Greeks call this profile trochilus. Scotia comes from the Greek word for darkness, a reference to the dark shadow in the hollow.

Position in the column base

From bottom to top, the Attic base is made up of:

1. A square plinth.
2. A lower torus, wider and heavier.
3. A narrow flat band (fillet).
4. The scotia.
5. Another fillet.
6. A smaller upper torus, on which the column shaft rests.

The scotia also appears in Ionic bases, sometimes doubled.

Difference from a cavetto

A cavetto is a simple concave moulding with a quarter-circle profile. A scotia is deeper and asymmetrical: its profile is usually built from two arcs of different radii, so the hollow projects further at the bottom than at the top.

Applications

• Bases of classical columns and pilasters, and of columns in Neoclassical buildings.
• Pedestals, balusters and plinth blocks.
• Mouldings in stone, plasterwork and timber, for example on fire surrounds and newel posts.

Practical tips

• Recognising it: a deep hollow between two rounded rings at the foot of a column is almost always a scotia.
• Repair: the deep hollow traps dirt and moisture and is vulnerable to frost damage on outdoor columns; inspect it carefully.
• Reproducing it: keep the asymmetry. A symmetrical hollow makes the base look flatter and less classical.

Related terms

• Torus moulding
• Attic style
• Column base
• Cavetto
• Cove moulding
• Column

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