Entasis

From Wikipedia, the free encyclopedia

schema of a Corinthian column

In architecture, entasis is a design technique used to counteract a certain optical illusion. When a column or other structure is designed with parallel sides, the sides appear to have a slight inward curve. Entasis is the inclusion of a slight outward curve in the sides - making them not parallel - to counteract this optical effect. Except in the temple, the floor below has a curvature. The goal, somewhat paradoxically, is to give the appearance of straight lines through the use of curves and optical illusion.

Basilica at Paestum

Probably the first use of entasis was in the construction of the Egyptian pyramids, but it can also be observed in Classical period Greek column designs, for example in the doric Order-temples in Segesta, Selinus, Agrigento and Paestum. It was only very rarely used in Hellenistic and Roman period architecture. The temples built during these periods were higher than those of the Greeks, with longer and thinner columns. Noted architects like the Renaissance master Andrea Palladio also used it in their buildings.