MOULDINGS, in architecture, prismatic or annular solids, formed by plane and curved surfaces, and employed as orna ments.
All parallel sections of straight mouldings, all the sections of annular mouldings, made by a plane at the same inclination to the axis, and, in general, all sections of mouldings made by a plane perpendicular to any one of the arrises. are similar figures. Mouldings are divided into two classes, or kinds ; Grecian and Roman.
Grecian mouldings arc formed of some conic section, as a portion of the ellipsis or hyperbola ; and sometimes even of a straight line, in the form of a chamfer.
Roman mouldings have their sections composed of the arcs of circles, the same moulding having the same curva ture throughout.
In both Grecian and Roman mouldings, their species is determined by the position of their extremities, or the cir cumstance of their being concave or convex : if the section be a semicircle projecting from a vertical diameter, the mould ing is called an astragal, bead, or torus.
If the moulding be convex, and its section the quarter of a circle, or less, and if one extremity project beyond the other, that is, approach nearer to the eye than the other, it is termed a Roman 0(010; and if this Roman ovolo project equal to its height, and the portion employed be the quadrant of a circle, it is then called a quarter-round. If the section of a mould ing be concave, but in all other respects the same as the last, it is denominated a eavetto.
If the section of a moulding he partly concave and partly straight, the straight part being vertical and a tangent to the concave part, and the concavity equal to, or less than the quadrant of a circle, the moulding is denominated an apophygo, scape, spring, or range: this is used in the Ionic and Corin thian orders for joining the bottom of the shaft to the base. as well as to connect the top of the fillet to the shaft under the astragal.
If the section be one part concave and the other convex, and so joined as to have the same tangent, the moulding is named a cymatium; but Vitruvitts calls all crowning or upper members cymatiums, whether they resemble the one now described or not.
If the upper projecting part of the cymatium be a concave, it is called a sima-recta ; this is generally the crowning mem ber of cornices, but is seldom found in other situations ex cept on pedestals or altars.
If the upper projecting part of the eymatium be convex, it is called a sima-reversa, and is the smallest in any compo sition of mouldings, its office being to separate the larger members. Though seldom used as a crowning member of cornices, it is frequently employed with a small fillet over it, as the upper member of architraves, capitals, and imposts.
If the convex part of a moulding recede and meet a hori zontal surface, the recess ti,rmed by the convexity and the horizontal surthee is termed a It' the section of the mouldiag be a convex conic section, the intermediate part of the curve projecting only a small distance the greatest projecting extremity, and the tan gent tic the curve at the receding extremity meeting x hori zontal line, produced forward without the curve at the upper extremity, the moulding is called an °coif/. This is generally employud above the eye, as a crowning member in the Grecian Doric. Ovtdos may be used in the same of dillibrent sizes ; it is sometimes cut into egg-and tongue, nr egg-and-dart, when it is termed echinus. It is employed instead of a turns in the base of the moluonucnt of In sierates, at Athens. The contours of ovolos are generally elliptical or hyperbolical curves. These curves can be regulated to any degree of quickness or Ilatness; the parabola can also be draw n under these conditions, but its curvature, being of the intermediate species, does not atftrd the variety of change admitted by the other two.
It' the section be a concave semi-ellipsis, having its conju gate diameter such that the one may unite the of its projections, and the other diameter parallel to the horizon. the moulding is termed a scotio. This is alway employed below the level of the eye, between two Lori. One extremity has generally a greater projection than the ()dal., the greater projection being, nearest to the level of the eye.
If the section of the moulding lie the two sides of a right the one vertical, and the other, of coarse, horizontal, it is termed a fillet ha rod. or corona. A fillet is the smallest reetnnonbtr member in any composition of Its altitude is generally equal to its projection ; its purpose is to separate two principal members, and it is used in all under such cirournstances. The corona is the prineipal member or a cornice. The favi•i is a prineipal member in an arehitrave as to height, but its projection is not IllDre than that of it fillet, Hitless it be the lower fivia, where the soffit is the whole breadth the top, or sometimes cu en of the hottum of the Mouldings are either plain. with egg:, and w hi] folMge displayed in a variety of forms; some enrichments are pecnlia• to eeirain fOrIIIS, or egy-and-tongne, to the ovolo.
Nlouldings in assemblage. are used in the formation of cornices, a•ehitraves, bases. capitals. &e. See A ellenvrtn, ('AVF.TTO, CVNIATIUM. ECITiNt's, ()VoLo, Ql'ARTE13.-HoUND,