Oval domes: history, geometry and mechanics (Q1011813)

First a historical outline is given of the origin and application of the oval (primary meant ``egg-shaped'') in architecture: Mesopotamia and Egypt, Greece and Rome, Middle Ages, the 16th century, and Renaissance. Then the geometry of oval domes is discussed. From the 18th century on, the study of conics in elementary courses of geometry taught the learned people to consider the oval as an approximation of the ellipse, an ``imperfect ellipse'', e.g. formed from circular arcs. The ellipse has very rarely been used in building. Finally a brief exposition of the mechanics of oval arches and domes is given, and the role of geometry in the masonry of oval arch and dome design is discussed. All this is illustrated with numerous figures.