The Facia is generally plain, but the decoration, if used should, following the principle, be rectilinear in character; such as vertical flutings, or the key detail, both of which are used. _Dentils_ Dentils, which form a distinctive feature in cornices, are a series of rectilinear blocks, attached to a Facia, and may be placed in the category of supporting members. In their formation they are carved back from a facia of the requisite projection. In proportion they should be from one and a half to one and three quarters their width in height, the intervals between being about half the width. The first Dentil at the angle, lines flush with the return face of supporting Facia leaving a right angular interval between the two end Dentils. This space is sometimes occupied by a pendant knob, acorn-like in shape. The heads of intervals are often sloped backwards and downwards, or occupied by a narrow fillet set back from face. Below the Dentils the supporting Facia is displayed to about the height of a fillet. Considerable license prevailed in the later developments of the Renaissance in the decoration of mouldings, license which is permissible providing the general principle be borne in mind. The concensus of opinion is in favour of repetition of a simple unit and absence of variety. The vertical tendency resulting from the bi-symmetrical character of the unit is desirable, and in happy contrast to the horizontal direction of the moulding, while it also emphasises the sense of structural support. [Illustration: DETAIL OF THE DENTIL No. 136.] The profiles also are amenable to considerable variation, the curves being the direct result of Geometry, or Freehand, either treatment being a matter of attitude and discretion. _Employment_ When employed in Architecture the forms and proportions given will be found most suitable. In interior decoration and structural work, as in furniture, considerable latitude is permissible. It must be understood that the profiles of mouldings should not be designed merely for the play of line, but for the effect resulting from light and shade. In those close to the eye and in fair light, elliptic curves will be more effective than more rounded sections, which are most suitable to remote positions. In composition, mouldings of curved profile should always be separated by fillets or occasionally a facia, and the various members associated with regard to their functional purpose. Obvious repetition of the same dimension is to be avoided, and contrast should exist not only in the shapes of profiles, but also in their respective heights. [Illustration: MODIFIED PROPORTION DUE TO PERSPECTIVE No. 137.] _Attitude_ Attitude must be taken into account, as, for instance, in a cornice which is above the eye level it is apparent that the mouldings will not appear in elevation but in perspective; and not only the respective heights will be visible, but also the projections.