It also occurs as a supporting moulding under the capping of the pedestal, and is used in similar positions in the other orders.
The Binding mouldings, the Torus and the Scotia, appear chiefly on columns and pilasters, particularly the Scotia, which is essentially a base moulding.
The Torus is a convex curve composed of a full half circle, with upper fillet one-fifth to one-sixth the total height. The projection is decided by the curvature, which is based on a semi-circle with centre slightly in advance of the vertical line of fillet.
The Torus varies in size according to position. For instance, in the base of the Ionic column two are employed, the lower being the larger. It is also invariably used on a smaller scale as a necking moulding beneath the Capitals; in the small form it is commonly known as a bead or astragal.
This employment of the Torus is distinctly appropriate and suggestive in the sense of imparting strength by binding. When used in other positions its purpose should be equally evident.
The Scotia in section is a deeply recessed concave curve with upper fillet, and is generally used between the upper and lower Torii of the base.
The upper fillet is of less projection than the lower extremity of curved profile. The extreme projection being merely equal to the height of curve and that of the upper fillet about one-half, the fillet being about one-fifth the total height.
The foregoing constitute the range of mouldings with curved profiles, but there is another member, the Facia, that is an important feature in composition.
The Facia, which is rectilinear in form with external face vertical or slightly inclined, may be classed with the binding mouldings.
With regard to proportion, the height of the Facia should either exceed or be less than that of the curved moulding with which it is invariably surmounted. The projection being either considerably less or more than its height.
When used in the cornice or in the capping of pedestals its under face is generally recessed, this recess being equal to the height of the top fillet of supporting moulding.
Only occasionally the Facia is furnished with an upper fillet (for instance, when it occurs immediately below the Cyma Recta) to which it is reconciled by a Cavetto curve.