77. The base of the Ionic order (Plate XII) is twenty-three and five-tenths parts in height; it is composed of a plinth of eight, a first torus of six, a fillet of one and five-tenths, a scotia of three, a second fillet of one, and a second torus of four. The projection of the base, including the conge of the shaft, is eight, of which two is the projection of the conge. This is shown on the enlarged section of the pedestal and column base at the left: 78. The cymatium or cap of the pedestal is fourteen in height, divided as follows: a fillet, one and five-tenthg, cyma-recta, two and five-tenths, surmounted by a small fillet of five-tenths, a corona of five and five-tenths, a cyma-reversa of two, and a listel of two. The projection of the cap from the plinth of the column base and the die of the pedestal is nine, of which two parts are for the cyma reversa and listel, and three and five-tenths for the corona in which is cut a small drip. The base of the pedestal is forty-five in height divided thus: first plinth, twenty-five; second plinth, ten; torus, three and five-tenths; fillet, one; cyma-reversa, four; upper fillet, one and five-tenths. The projection of the base is eight, of which one is for the cong4, four for the cyma-reversa, two for the torus, and one for the first plinth.
79. The impost is twenty-three parts high and is sub-divided as follows: astragal three; frieze six and five-tenths; fillet one; quarter round, two and 417e-tenths; corona, six; cyma-reversa, two; listel, two. The Projection of the impost is eight; two for the cyma and listel, three for the corona, and three for the quarter round and fillet. The archivolt is twenty-five in width composed of a first band of seven, a cyma of two, a second band of nine, a bead of one and five-tenths, a cyma of three, and a listel of two and five tenths. The projection of the archivolt is five, of which one and
five-tenths is for the projection of the second band beyond the first, one for the bead, and two and five-tenths for the cyma and its fillet.
80. The relation of Ionic column taper to pilaster taper (Fig. 12) is as follows: The lower diameter of the Ionic column is forty-five, and its upper diameter thirty-nine, the difference is six, which, divided into three parts, as in the Doric order, gives for the lower width of the pilaster forty-three, and for the upper width forty-one. The projections of the bases differ only in the conge of the shaft which measures three for the pilaster and two for the column.
The disposition of the capital is the same for the pilaster as for the column so far as the volutes are concerned, the catheti being the same distance (forty-two parts) from each other. It may be noticed only in the plan of the capital of the pilaster, that the outer edge of the quarter-round formS an arc of a circle drawn with a radius of thirty-five,while the astragal is rectangular in plan like the face of the pilaster, and, running between the volutes, con nects them with one another.
81. In Fig. 13 will be found a drawing of the Ionic console. Sometimes one of these consoles is placed at the crown of an arch intersecting the archivolt. The sides of such a console radiate from the center of the arch; the stone on which the console is carved is called- the "key" of the arch or the "keystone."