Entasis is the subtle convex curvature in the middle of a column shaft that makes the column appear visually straight. Without this correction, a perfectly straight column would look concave or pinched in the middle. Greek and Roman builders therefore applied entasis as standard practice in their temples.
How entasis works
Through an optical illusion, a tall, tapering column with perfectly straight sides appears concave. The eye sees it as pinched in the middle. To correct this, the ancient builders shaped the column so that it is:
- At the base — widest (the column base)
- In the middle — slightly thicker, due to entasis
- At the top — tapering towards the capital
The extra thickness in the middle is small — often only a few percent of the column diameter — but enough to remove the illusion.
History
Entasis was already applied in:
- Egyptian temples — sometimes faintly visible
- Greek Doric temples — the Parthenon (5th century BC) is a famous example
- Roman architecture — sometimes less pronounced
- Renaissance — rediscovered and theorised by Vitruvius and Palladio
In the Parthenon columns the greatest swell sits at roughly one third of the column height from the base.
Entasis in modern construction
In replicas of classical architecture — museums, churches and public buildings of the 18th and 19th centuries — entasis is still applied. In contemporary minimalist architecture, the technique is rare because columns are usually short and plain in form.
Other optical corrections
Classical temples used more visual tricks:
- Stylobate curvature — the platform is gently convex
- Column inclination — outer columns lean slightly inwards
- Corner column thickening — corner columns are slightly thicker
Related terms
- Column
- Capital
- Base
- Doric
- Ionic
- Corinthian
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