No. 170. Detail of Balusters.
an ovolo and fillet, which are circular on plan. The necking is separated from the shaft by a small torus and fillet. The base has for its lowest member a square plinth, which occupies rather less than half the height and is equal in width to the extreme diameter of the bulbous shaft. Above the plinth is a scotia and a necking moulding, which are circular on plan.
Spacing of Balusters
The balusters should be spaced with not more than half their diameters or less than a third between their bases, except when employed on the rake of steps, when they may be slightly closer.
Balustrading
In a balustrading an unequal number of balusters should always be used, and not less than five in one group exclusive of the half balusters which are attached to the flanking or dividing dies. Seven and nine form very satisfactory groups, but if more than nine are necessary for the space to be filled, intermediate dies must be interposed, and these may vary from two-thirds to three-quarters the width of the principal dies.
In some cases, when a large number of balusters are to be grouped, the dies are flanked by half dies, which are less in projection than the dies themselves.
Balustrades are sometimes used above the cornice of a building, and their height should not be more than four-fifths or less than two-thirds the height of the entablature. This height would be exclusive of the plinth on which the balusters are raised. The height of the plinth is determined by the height of the building, and the projection of the cornice, as its purpose is to raise the balusters so that they may be seen from the ordinary point of view. The principal dies may be placed over columns or pilasters and should be equal in width to the upper diameters of these, though flanking half dies may be used in addition to avoid an appearance of thinness. The plinth and capping mouldings always follow the plan of the principal dies, and are carried in unbroken lines across each interval.