Oculus (architecture)

Anoculus(fromLatinoculus'eye';pl.:oculi) is a circular opening in the center of adomeor in a wall. Originating inantiquity,it is a feature ofByzantineandNeoclassical architecture.It is also known as anœil-de-bœuffrom theFrench,or simply a "bull's-eye".^[2]

History[edit]

Classical[edit]

The oculus was used by theAncient Romans,one of the finest examples being that in the dome of thePantheon.Open to the weather, it allows rain and air to enter and fall to the floor, where it is carried away through drains. Though the opening looks small, it actually has a diameter of 8.7 m (29 feet), allowing it to light the building.

Byzantine[edit]

The oculus was widely used in the architecture of theByzantine Empire.It was applied to buildings inSyriain the 5th and 6th centuries and again in the 10th century. InConstantinople'sMyrelaion Church(c. 920), there are two oculi above thestringcourseon both lateral facades.^[3]

Renaissance[edit]

Early examples of the oculus inRenaissance architecturecan be seen inFlorence Cathedral,in the naveclerestoryand topping the crowns of the arcade arches.^[4]

Neoclassical[edit]

Since the revival of dome construction beginning in theItalian Renaissance,open oculi have been replaced by light-transmittingcupolasand other round windows, openings, andskylights.They can be seen in the pediments ofPalladio'sVilla Rotonda,though not in the dome. Use of oculus windows became more popular inBaroque architecture.Widely used byNeo-Palladianarchitects includingColen Campbell,one can be seen in the dome ofThomas Jefferson'sRotundaat theUniversity of Virginia.^[2]^[5]