Monday, June 16, 2014

Word of the Day -- Ogee

An ogee is a curve (often used in molding), shaped somewhat like an S, consisting of two arcs that curve in opposite senses, so that the ends are parallel. It is a kind of sigmoid curve.

The term has uses in architecture, mathematics, and fluid mechanics, as well as marine construction, clock design and plastic surgery.  But for our purposes, we are going to stick with the term as it is used in archtecture.

In architecture, the principal use of the term is to describe an arch composed of two ogees, mirrored left-to-right and meeting at an apex. Ogee arches were a feature of English Gothic architecture in the later thirteenth century.

A building's surface detailing (indoors or out) may have a molding with an ogee-shaped profile, consisting (going from low to high) of a concave arc flowing into a convex arc, with vertical ends; if the lower curve is convex and higher one concave, this is known as a Roman ogee, although frequently the terms are used as if they are interchangeable and for a variety of other shapes. Alternative names for such a true Roman ogee molding include cyma reversa and talon.[3]

The cyma reversa form occurs in antiquity. For example, in ancient Persia, the Tomb of Cyrus
featured the cyma reversa.[4] The cyma reversa is also evident in ancient Greek architecture.[5] The ogee shape is one of the characteristics of the Gothic style of architecture, especially decorative elements in the 14th and 15th century late Gothic styles called Flamboyant in France and Decorated in England. Ogee windows and arches were introduced to European cities from the Middle East. The ogee curve is an analogue of a "cyma curve", the difference being that a cyma has horizontal rather than vertical ends.

The ogee and Roman ogee profiles are used in decorative molding, often framed between moldings with a square section. As such it is part of the standard classical decorative vocabulary, adopted from architrave and cornice moldings of the Ionic order and Corinthian order. An ogee is also often used in the "crown molding" frequently found at the top of a piece of case furniture, or for capping a baseboard or plinth, or where a wall meets the ceiling. An ogee molding may be run in plaster or wood, or cut in stone or brickwork.

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