This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
The style of mouldings arising in the cornice shop are chiefly Roman, and are obtained by using the arcs of a circle. In some cases, Greek mouldings are used, the outlines of which follow the curves of conic sections; but the majority of shapes are arcs of circles. In Figs. 268 to 272 inclusive, the student is given a few simple lessons on Roman mouldings, which should be carefully followed. As all pattern-cutters are required to draw their full-size details in the shop from small-scale drawings furnished by the architect, it follows that they must understand how to draw the moulds with skill and ease; otherwise freehand curves are made, which lack proportion and beauty.
In Fig. 268, A shows the mould known as the cyma recta, known in the shop as the ogee, which is drawn as follows:
Complete a square abcd; draw the two diagonals a c and b d, intersecting each other at e. Through e, draw a horizontal line intersecting a d at f and b c at h. Then, with f and h as centers, draw respectively the two quarter-circles a c and e c.
Busch Hall, the Chemical Laboratory. The Building is 290 Feet Long, 60 Feet Wide. Cost $110,000.
THREE FIREPROOF BUILDINGS OF THE UNIVERSITY OF WASHINGTON, ST. LOUIS, MO.
Illustrating the Restful Effect of a Long, Almost Unbroken Roof-Line.
In Fig. 269, B shows the cyma reversa, known in the shop as the ogee, reversed. Complete a square a b c d, and draw the two diagonals b d and a c intersecting at e; through e, draw a vertical line intersecting a b at f and c d at h, which points are the respective centers for the arcs a c and e c.
C in Fig. 270 shows the cavetto, called the cove in the shop, which is drawn by completing a square a b c d. Draw the diagonal b d at 45°, which proves the square; and, using d as a center, draw the quarter-circle a c. in Fig. 274, D represents the ovola or echinus, known in the shop as the quarter-round, which is constructed similarly to C in Fig. 270, with the exception that b in Fig. 271 is used to obtain the curve a c.
E in Fig. 272 is known as the torus, known in the shop as a bead-mould. A given distance a b is bisected, thus obtaining e, which is the center with which to describe the semicircle a b.
All of these profiles should be drawn by the student to any desired scale for practice. In preparing mouldings from sheet metal, it is sometimes required that enrichments are added in the ogee, cove, and bead. In that case the mould must be bent to receive these enrichments, which are usually obtained from dealers in stamped or pressed sheet-metal work. Thus, in Fig. 273, F represents a front view of a crown mould whose ogee is enriched, the section of the enrichment being indicated by a b in the section, in which the dotted line d c shows the body of the sheet-metal moulding bent to receive the pressed work. In Fig 274, H represents part of a bed-mould in which egg-and-dart enrichments are placed. In this case the body of the mould is bent as shown by c d in the section, after which the egg-and-dart is soldered or riveted in position. J in Fig. 275 represents part of a foot-mould on which an enriched bead is fastened. The body of the mould would be formed as indicated by c in the section, and the bead a b fastened to it. This same general method is employed, no matter what shape the pressed work has.