This article is about the architectural term. For the art installation, see Jones/Ginzel. For the virtual reality device, see Oculus Rift. For other uses, see Eye (disambiguation) and Ocular (disambiguation).
An oculus, plural oculi, from Latin oculus: eye, denotes a circular opening in the centre of a dome or in a wall. Originating in Antiquity, it is a feature of Byzantine and Neoclassical architecture. It is also known as an œil de boeuf from the French, or simply a "bull's-eye".
1 Classical example,
2 Byzantine architecture,
3 Neoclassical revival,
4 Other uses,
6 External links,
The oculus was used by the Romans, one of the finest examples being that in the dome of the Pantheon. Open to the weather, it allows rain 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 27 ft (8.2 m) allowing it to light the building just as the sun lights the earth. The rain also keeps the building cool during the hot summer months.
The oculus was widely used in the architecture of the Byzantine Empire. It was applied to buildings in Syria in the 5th and 6th centuries and again in the 10th century. In Constantinople's Myrelaion Church (c. 920), there are two oculi above the stringcourse on both lateral facades.
Early examples of the oculus in Renaissance architecture can be seen in Florence Cathedral, in the nave clerestorey and topping the crowns of the arcade arches.
Since the revival of dome construction beginning in the Italian Renaissance, open oculi have been replaced by light-transmitting cupolas and other round windows, openings, and skylights. They can be seen in the pediments of Palladio's Villa Rotonda, though not in the dome. Use of oculus windows became more popular in Baroque architecture. Widely used by Neo-Palladian architects including Colen Campbell, one can be seen in the dome of Thomas Jefferson's Rotunda at the University of Virginia.
Effect of the view into a cupola through an oculus under natural light (Wambierzyce, Poland)
Detail of oculus set in a cartouche with the head of Mercury (Beaux-Arts New York and New Jersey Telephone Company Building, Brooklyn)
View of an oculus opening into a cupola in the Hasht Behesht, Isfahan (1699)
Oculi in San Pedro, Calasparra, Spain
Chapelle Saint-Gabriel, Tarascon (12th century)
Oculus, Latin for eye, is also used in medicine and optics.
In archaeology, oculus is the name given to a motif found in western European prehistoric art. It consists of a pair of circular or spiral marks, often interpreted as eyes, and appears on pottery, statues and megaliths. The oculus motif may represent the watchful gaze of a god or goddess and was especially common during the Neolithic period.
In graphical perspective, Oculus is abbreviated O and denotes the point in space where a viewer sees a scene to be portrayed on a picture plane. When depiction of a scene was taken over by a camera with photography, the "eye point" or Oculus became the station point.