PEDIMENT, in architecture, a kind of low pinnacle, serving to crown porticos, or finish a frontispiece ; and placed as an ornament over gates, doors, windows, niches, altars, &c.
The pinnacles of the ancient houses. Vitruvius observes, gave architects the first idea of this noble part ; which still retains the appearance of its original.
The parts of the pediment are, the tympanum and its cornice. The first is the panel. naked, or area of the pedi ment, enclosed between the cornice, which crowns it, and the entablature, which serves as a base, or soele.
Architects have taken a great deal of liberty in the form of this member ; nor do they vary less as to the proportion of the pediment. The most beautifid. according to Daviler, is that where its height is about one-fifth of the length of its base. The pediment is usually triangular, and sometimes an equilateral triangle ; this is also called a pointed pediment. Sometimes it is circular; though Pelibien observes, that we have no instances of round pediments in the antique. beside those. in the ehapels of the IZOttilida. Sometimes its upper cornice is divided into three or flan' sides, or light lines; sometimes the cornice is cut, or open at top, which is an abuse introduced by the moderns, particularly by Michael Angelo. For the design of this part, at least over dtmrs, windows, &c.,, being chiefly Ibr the purpose of sheltering those underneath from the rain, to leave it ()pen in the middle is evidently to frustrate its end.
Somedines the pediment is formed of a couple of scrolls or wreaths, like two consoles joined together. See CONSOLE.
Sometimes, again, the peditnent is without base, or its lower eornice is cut out, all but what is bestowed on two columns, or pilasters, and on these an arch or sweep, raised in lieu of an entablature; of which Sorlio gives an instance in the antique, in a Corinthian gate at Foligny, in Umbria ; and Daviler, a more modern one, in the church of St. Peter at Rome.
Under this kind of pediments, also come those little arched cornices, which fbrin pediments over doors and windows, supported by two consoles, in lieu either of entablature or columns.
Sometimes the pediment is made double, i. e. a less pedi ment is made in the is mpanum of the larger, on account of some projerture in the middle; as in the frontispiece of the church of the great Jesus, at flotne ; but this repetition is an :Muse in architecture, though authorized by some very good buildings; as may be seen in the large pavilion of the Louvre, where the Caryatides support three pediments, one in another.
Sometimes the tympanum of the pediment is cut out, or left open, to let in light; as we see under the portico of the Capitol. at Rome.
lit all the remains of Grecian architecture, the horizontal cornice is never interrupted or broken, nor is there any instance of a circular pediment, nor of any open at the top. The proportion of the tympannm is from one-fifth to one ninth pail, of the span. in the pediments which remain of Grecian edifices. In the Doric tel pullet) at Athens, the height of the tympanum is about one-seventh part of its triangular base. The portico of the temple of Theseus is hexastyle; and the height of the tympanum of the pediment is about an eighth part of the span of its triangular base. The portico or the temple of Minerva is oetostyle; and the height, of the triammlar tympanum, about one-ninth of its base. So that the higher the pediment, the less is the height in proportion. And thus the pediments of doors and ought to be still higher, as is verified in the frontispiece of the entrance-door of the Tower of the Winds, at Athens, where the height of the tympanum is only one fifth part of the triangular base.
Vitruvius expressly disapproves of the use of dentils, modillions, or =tides, in pediments, for this reason; that as mutules and modillions were the representations of rafters, and details the representations ins of laths, and as these essential parts were always placed in the inclined sides of the roof the ridge, to overhang the eves, it would certainly have been improper to use mutules. modillions, or dentils, in a situation where the originals themselves never existed.
Arches under pediments, is an abuse in architecture.