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If the convex part of a moulding recede and meet a hori-zontal surface, the recess formed by the convexity and thehorizontal surface is termed a quirk.

If the section of the moulding be a convex conic section,the intermediate part of the curve projecting only a smalldistance from the greatest projecting extremity, and the tan-gent to the curve at the receding extremity meeting a hori-zontal line, produced forward without the curve at the upperextremity, the moulding is called an ovolo. This is generallyemployed above the eye, as a crowning member in theGrecian Doric . Ovolos may be used in the same compositionof different sizes ; they are sometimes cut into egg-and-tongue,or egg-and-dart, and termed echinus. The ovolo is employedinstead of a torus in the base of the monument of Lysicrates,at Athens . The contours of ovolos are generally ellipticalor hyperbolical curves. These curves can be regulated toany degree of quickness or flatness ; the parabola can alsobe drawn under these conditions, but its curvature, being ofthe intermediate species, does not afford the variety of changeadmitted by the other two.

If the section be a concave semi-ellipsis, having its conju-gate diameter such that the one may unite the extremitiesof its projections, and the other diameter parallel to thehorizon, the moulding is termed a scotia. This is alwaysemployed below the level of the eye, between two tori. Oneextremity has generally a greater projection than the other,the greater projection being nearest to the level of the eye.

If the section of the moulding be the two sides of a rightangle, the one vertical, and the other, of course, horizontal,it is termed a fillet, band, or corona. A fillet is the smallestrectangular member in any composition of mouldings. Itsaltitude is generally equal to its projection ; its purpose isto separate two principal members, and it is used in allsituations under such circumstances. The corona is theprincipal member of a cornice. The facia is a principalmember in an architrave as to height, but its projection isnot more than that of a fillet, unless it be the lower facia,where the soffit is the whole breadth of the top, or sometimeseven of the bottom of the shaft. Mouldings are either plain,or enriched with eggs, and with foliage displayed in a varietyof forms; some enrichments are peculiar to certain forms, asegg-and-anehors, or egg-and-tongue, to the ovolo.

Mouldings in assemblage are used in the formation ofcornices, architraves, bases, capitals, &c. See Apophyge,Cavetto, Cymatium, Echinus, Ovolo, Quarter-Round,Scape, Scotia, Sima-Recta, Sima-Reversa.

Plate I —Figure 1, a quarter-round.

Figure 2, a cavetto, being exactly the reverse of the lastfigure; both being the quarter of a circle.

Figure 3, the sima-reversa, composed of two quadrantsof a circle.

Figure 4, the sima-recta, being the reverse of the sima-reversa.

Figure 5, a torus, which is a semicircle described upona vertical diameter.

Figure 6, a scotia, which, projecting equally at eachextremity, occasions the contour to be exactly the reverse ofthe torus.

The following are the methods of describing Romanmouldings, where the projections and heights are unequal ;the extremities of the moulding being given.

Figure 7.— To describe the Homan ovolo. Let a be theupper extremity, and b the lower ; take the vertical line orheight; from b, with that radius, describe an arc; from a,with the same radius, describe another arc, cutting the formerat c; then from c, with the same radius, describe the arc a b,which will be the contour required.

Figure 8.— To describe the cavetto. With a radiusto the height of the moulding, from the points A and B ® eSLarcs, cutting each other in c; then from c, with theradius, describe the arc A b, which will give the contothe cavetto required. id

Figure 9.— To describe a sima-reversa, that shall to ^straight line at the points of contrary flexure. J° in p ;projections A and b by the straight line A B ; bisect A ;draw the tangent ED, parallel to a line given in P os1 .,,jthrough d draw c c, perpendicular to k d ; bisect A ®perpendicular, g c; from the intersection c, describe *' ^

a g d ; make D c equal to D c'; from the lower P o1 ' ^ j,describe the arc D b: then the curve of contrary flexure, A iwill be the sima-reversa required.

Figure 10.— To describe a sima-recta to touch a ,line at the points of contrary fieocure, parallel to a l‘ ne fa s eC *in position. Join the points of projection A and B > jpA b in d, and draw the line d e parallel to the line g 1 ' phposition ; bisect ad by tbe perpendicular eg; from O p c,the radius'c d, describe the arc A d ; make D c equal ^ p 0and from the other point c within, describe D B : thenis the sima-recta required.

Figure 11.— To describe the Grecian ovolo, two tobeing given, as also their points of contact. Let A E j 11 ' tl) ebe the tangents ; A and b the points of contact; comp eet^tparallelogram b e a d; produce b d to c, and make » t o'to d b; divide e a and d a each into the same m" 11 ^

equal parts ; through the points of division in

E A,

J,... 1C , ..t.UL... nflil 1

lines to b ; draw lines to c through the corresponding, ^ t l]«in d A, to meet the corresponding lines drawn to B ;intersections will be in the curve of an ellipsis. 1

The 1

W

part, a q, is a continuation of the same curve. T ,

The same directions extend to Figures 12, 13, 1the following difference may be observed : . tij*

In Figure 11, the tangent b e is regulated by l* 1 ’.point e in the middle of AD. In Figure 12, the Pf"| none-third of AD from the bottom. In Figure 1 ’.^S 1middle of ad, as in Figure 11. In Figure 14, theone-third of A D, from A. Then, according as the^is lower or higher, the curve will be quicker or ffivj j2 1same projection: so that, among these curves, 1Wthe boldest, and Figure 14 the flattest. g js 1 ^

When e b and a e are nearly equal, the moulding p ,lidboldest of any, taking d e at the same height; ijjngthe projection is very great, or very small, the mextremely flat. fbt

Figure 15.— The same data being given, to dtGrecian ovolo ; supposing the point of contact, (0 jsextremity of one of the axes. Draw b k perpendm 0 ‘ j |also pc perpendicular to bk, for the other ax .' 9 ’^point P may be above A ; then e b and P c will. c e VTo find the major axis : from A, with thedescribe an arc, cutting pc at f ; draw A F, anto meet bk in i ; make c p equal to A i; then w 1 s( , r jb ethe major axis, and c b, half the minor axis, - .

curve b A p Q, which will be the moulding requ' r ® ' ff 0 ofThis method forms the most beautiful moul ' pit S L t |r

the curvature being continually increased from th " yj ' ,,j

The same description applies to Figures 16 ! >» ^ piS”

regard to the quirk at the point Q, it will be nio ^ p ;

the point A is more or less distant from Q. ang' e ® V*

The quantity of curvature depends upon the * ta teso that when the angle e b d is less, the cu P J

be greater. .

For a description of mouldings employed in t0

Gothic Architecture, we must refer thesubjects treated of unde” these respective titles*

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