Both the layout for the Composite and the Corinthian capitals share common characteristics. In the Composite capital, however, there is an echinus and astragal set below the abacus.
This elevation of the Composite Capital shows the first stage of drawing the capital, before the leaves and other ornament is added. The capital is viewed looking straight at the convex portion of the capital which is illustrated in the partial plan above the elevation.
The capital is 7/6 D high and is 9/6 from tip to tip of the abacus. The abacus which is 1/6 D high consists of an ovolo, fillet, conge and fascia. In many versions of the Corinthian one finds a large conge at the abacus which is indistinguishable from the fascia. Below the abacus is a cylindrical bell that tapers down to 5/6 D from the lip of the bell. The lip is a beak molding with a thickness of 1/18 or 1/12 D.
Situated below the bell, the astragal can be drawn within a 1/12 D by 1/12 D square. From the outermost point on the square, a dashed line should be drawn to the tip of the abacus. This line defines the boundaries for drawing the acanthus leaves of the capital.
Another set of dashed lines drawn from the outer edge of the bottom of the bell at 45 degrees will give the width of the abacus, previously noted as 9/6 D.