The shaft is circular on plan and invariably tapered.
The base is composed of mouldings, which are circular on plan, and a rectangular block or plinth.
The capital is circular on plan, and in the Doric and Corinthian orders is divided from the shaft by a necking moulding. The capital is surmounted by a feature known as the abacus, which is rectangular on plan, but varies in detail in the different orders.
Columns may be isolated or engaged, that is, built into walls so that they form projections from the surface.
No. 153. Doric Order with Pedestal.
The pilaster is always engaged, and is rectangular on plan, but otherwise it has the same general features and proportions as the column.
The entablature is the superstructure supported by the columns. It consists of an architrave, which is the lowest part, a frieze, the intermediate part, and a series of projecting mouldings known as the cornice.
The pedestal, which occasionally forms a support for the columns, consists of a plinth, die and capping. The lower part or plinth is separated from the die by mouldings, and the capping is a projecting course of mouldings forming a simple cornice.