Page:Ware - The American Vignola, 1920.djvu/49

Rh The Cap and Base of the Pedestals, or of the Parapet or Continuous Pedestal, are called in a Balustrade the Upper and Lower Rails. The Baluster supports the Upper Rail as a Column supports an Entablature, and stands upon the Lower Rail as upon a Stylobate, Fig. 139. It has its own Cap, the height of which, including the Astragal, is one-quarter the height of the Baluster, and consists of a plain Abacus, Echinus and Fillet, and Necking. These three members are of about equal height, as in the Tuscan and Doric Capitals

The Base of the Baluster is also one-quarter its total height and resembles the Attic Base. The Scotia, as in the Greek Attic Base, is generally made the principal member.

Between the Cap and Base is the Shaft, or Sleeve, which has the outline of a Quirked Cyma Reversa, the greatest diameter, or Belly, coming at about one-fourth of its height, or one-third the height of the Baluster, Fig. 140. Its width at this point is also one-third the height of the Baluster, as is also that of the Plinth of the Base, exactly, and the width of the Abacus, almost. The Necking is less than half as wide. The point of contrary flexure in the Cyma Reversa is half way between Cap and Base, or between the Upper and Lower Rails. But these proportions are made somewhat lighter for use with the Ionic and Corinthian Orders.

The Rails are sometimes, in height, one-sixth and two-sixths of the space between them, like the Cap and Base of a Continuous Pedestal; but they are often made much heavier, even one-third and one-half.

Instead of the Cyma Reversa, a Beak Molding is often used, Fig. 141, and other variations are frequent. Of these, the most important is the so-called Double Baluster, which consists of two small Balusters, set together base to base just like the Baluster on the side of an Ionic Capital, Fig. 142. Vignola also used a high block under the Plinth. Balusters are often made square in section, like piers, instead of round, like columns.

Balusters are set about half their height apart, on centers. A Balustrade, like a Parapet, is intended to lean upon, and should not be more than 3 or 4 feet high. While, therefore, Columns and Entablatures are proportioned to the size of the buildings in which they occur, varying in height from 10 or 12 feet to 50 or 60, Balustrades, like steps, are proportioned to the size of the human figure, and in large buildings are relatively much smaller than in small ones. They thus serve, as do steps, and as does the human figure when introduced into a drawing, to indicate the scale of a building.

But in very large buildings Balustrades have sometimes been made of colossal dimensions, that on the top of the front of St. Peter's, for example, being about 8 feet high.