The use made of the pediment by the architects of the Renaissance was not always justified in the strictest sense. It was often used to vary the sky line, and to form door and window heads. Although the latter use can be to some extent justified in exterior work, a similar employment in interiors may be open to question. The sloping lines of the pediment are not always straight, sometimes they are in the form of a curve composed of a segment of a circle. The triangular and curved forms are often used alternately in a row of windows with good effect. The lines of the pediment mouldings are not always continuous; sometimes the sloping or the horizontal lines or both are broken. This is a treatment that cannot readily be justified as the pediment is a feature that implies shelter. Sometimes ogee curves take the place of the straight sloping lines, and these terminate towards the centre, with scroll ends, leaving an interval between them. [Illustration: DETAIL OF PEDIMENT No. 181.] The mouldings of the pediment are the same as those of the cornice, the crowning moulding of which is carried round and omitted in the horizontal course forming the base of the pediment. Beneath the cyma the mouldings of the cornice are repeated in their proper order, detailing at the lower angles on the top of the horizontal cornice, which terminates with the fillet above the facia. When dentils and modillions are introduced in the cornice they are invariably repeated in the mouldings of the pediment. The tympanum or face of the pediment should be in vertical alignment with the face of the frieze. When this space is small it is best left plain, but on a large scale the tympanum affords a very suitable position in which to place sculpture. The height of the pediment varies according to the width. Thus where the base is short, as in door and window heads, it will be comparatively higher than when used in a façade. The height may vary from a fourth to a fifth of the width of the base. _Doors_ Obviously door openings should be of sufficient size to admit the free passage of a tall person. The minimum height for ordinary doors in domestic buildings should be six feet nine inches, and the width two feet nine inches. For entrance doors under similar conditions the width may be three feet six, but when it is more than this the door should be in two halves. [Illustration: No. 182. General proportions of doors and windows.] The size of doors should be proportioned to the building, and should be designed to meet probable requirements, thus in public buildings door openings should not be less than six feet wide. Generally a satisfactory proportion may be obtained by making the height twice the width, and the framing architrave one-sixth the width of the opening. If a frieze and cornice are carried over the door the height inclusive of architrave should be half the width of the opening. [Illustration: No. 183. Door Treatment.