The effective appearance of the fillet, depends upon the truth of the small portions of cylinder and surface of which it is composed, which then meet exactly at a right angle. The clear definition thus obtained for a single fillet, is essential to the success of the little steps formed by a series, fig. 604, a tapering ornament employed beneath a projecting moulding, or when reversed, upon a plinth. The fillet is sometimes replaced by a quirk, occasionally introduced to give vigour to the ogee or ovolo. In the quirk the narrow width of cylinder which would have formed the vertical face of the fillet, is cut in as an acute angular groove, square as a surface on the horizontal side and meeting the termination of the curve at a sharp angle on the other, fig. 607, leaving the latter unsupported, which throws the groove or quirk into shadow.

The grouping of the various members described into complete mouldings, admits rather wide variations, but in this respect it is perhaps safer to conform generally to acknowledged architectural models. All such mouldings owe their elegance to contrast and balance; a bead or round being followed by a hollow, these reversed forms being rarely of similar dimensions, while they are more generally separated and diversified by fillets, quirks, or plain portions of the cylinder or surface. Two similar members or forms are very rarely placed in juxtaposition, even when differing in magnitude; exceptions to this general rule, being the beads at the base of the Doric column, the series of fillets before alluded to, and the reed, an ornament formed of a series of narrow beads, generally of uneven number. The latter ornament forms a flat band standing above the surface of the work, and the little beads of which it is composed are usually all of the same diameter and width, but in some varieties the beads are alternately of different widths. In turning, the reed is more exactly formed when produced by a single moulding tool called a barrel tool, the cutting edge of which is serrated to the required form.

Lastly, the accurately shaped mouldings so entirely subordinated to the form as to leave that the main attraction, cease to be superfluous, when so placed upon the work as to serve some direct purpose in addition to that of ornament. Thus for joining a larger to a smaller diameter at a base, or to support a cornice, or to connect the superstructure to its stem, to conceal a permanent joint, or to strengthen the edges of parts fitted or screwed together, which in subsequent use have to submit to frequent separation; the moulding is essential and its position obvious. When employed to break the monotony of long vertical lines upon shafts and other nearly parallel forms, except upon a pedestal, the moulding may be placed about the center of the length; but upon vertical curves and upon horizontal lines and curves, a more agreeable effect generally obtains by placing it rather decidedly above or below the center of the line to be divided; examples of all these purposes are given in the following illustrations.

The graceful, simple beauty of the ancient Greek and Etruscan vases, in great measure arises from the almost constant adherence to one principal curve, which, also admitting infinite fine gradations, was equally employed in the main outline and in the details of the enrichments. A few words may be permitted in analysis of the system, both as one that cannot be surpassed in results, and as particularly adapted to the production of good forms in the art of plain turning.

The beauty of the curve of the circle lies in its exact uniformity, that of the ellipse, neglecting its many gradations from a long to a more nearly round character of curve, both in uniformity and variety. The former yields the complete circle, the semi-circle, the quadrant and any portions less than the quadrant, all of which obviously possess one continuous curvature. The latter gives the ellipse, the semi-ellipse upon the long and that upon the short diameter, and any less portions taken anywhere around the curve; all of which, while still possessing relative uniformity, continuously vary in curvature. All sections or outlines contained by portions of the circle therefore, are similar in the character of their curvatures; but those contained by portions of the ellipse may be exceedingly varied, as the part of the curve used for the outline may be taken from the sides or the ends of the figure, as it may comprise parts of each in various relative degrees, and as it may be placed with its shorter or longer curvature uppermost. And when the curve of the outline is returned, that is proceeds in an unbroken line from concave to convex, the relative variety of outline is still more largely in favour of the ellipse.

The oval differing from the ellipse, in having the curvature of one end of the figure of less diameter than the other, uniformity is so far diminished, as to exist only in the similar curves of each pair of its quadrants; but as a consequence, the variation of outline into which the oval will compose, is twice that, that may be obtained from the ellipse. In addition, for the purposes of ornamental form, the difference of magnitude of the two ends of the oval may always be diminished or increased without interfering with its character, thus introducing further variety in the curve and the outlines that may be obtained from it.

The relative degrees of elegance, apparent upon comparison of vases or other axial forms having outlines of these three complete curves, are yet more striking when the curves cease to be axial, or when only portions are used to give the outline of the main figure, and also when these portions are employed on a smaller scale for enrichments. The oval is the key note of both form and ornament in the Etruscan Vases, in which beautiful creations a semi-circular section in the outline is rare; the oviform vases, figs. 670 to 678, drawn from the antique, exhibit outlines entirely derived from the oval line, and it will be seen also that portions of the oval are freely adopted in the outlines of many other of the illustrations. The figures especially referred to, which slightly indicate the varieties of similar forms that may be derived from the endless gradations of curvature of which the oval line is susceptible; show in addition, how subordinate the necessity for ornament may become when the main outline is intrinsically excellent. The turner is sometimes tempted to endeavour to annul want of success in beauty and proportion of outline, by superabundance of ornament, the simple yet subtle character of the Etruscan vases, shows how much may be attained by making outline the chief consideration; which valuable lesson is placed also in the well known aphorism directed against the opposite extreme, that the effort should be only to ornament construction, and not to construct an ornament.