Illustrated Architecture Dictionary
A dome is a convex roof.
Domes are categorized according of the shape of both the base and the section through the center of the dome.
- The base may be circular, square or polygonal (many-sided), depending on the plan of the drum (the walls on which the dome rests).
- The section of a dome may be the same shape as any arch.
Hemispherical dome: circular base with a semicircular section; half of a (completely round) sphere
Saucer dome: circular base and a segmental (less than a semicircle) section
Polyhedral dome; on a polygonal base whose sides meet at the top of the dome
Onion dome: circular or polygonal base and an ogee-shaped section.
Lantern: Many domes have a lantern (a turret with windows) to provide light inside.
Cupola: a dome on a circular base, often set on the ridge of a roof (but there are other definitions, also)
Semi-dome: half dome.A common feature of the apse at the end of Ancient Roman secular basilicas, Semi-domes are a common feature of apses in Ancient Roman and traditional church architecture, and mosques and iwans (rectangular hall or space, usually vaulted, walled on three sides, with one end entirely open) in Islamic architecture.
See also: Pendentive for information on the structural support system for domes.
Encyclopaedia Britannica: Dome
(online April 2020)
Dome, in architecture, hemispherical structure evolved from the arch, usually forming a ceiling or roof.
Domes first appeared as solid mounds and in techniques adaptable only to the smallest buildings, such as round huts and tombs in the ancient Middle East, India, and the Mediterranean.
The Romans introduced the large-scale masonry hemisphere. The dome exerts thrusts all around its perimeter, and the earliest monumental examples, such as the Roman Pantheon, required heavy supporting walls.
Byzantine architects invented a technique for raising domes on piers, permitting lighting and communication from four directions. The transition from a cubic base to the hemispherical dome was achieved by four pendentives, inverted triangular masses of masonry curved both horizontally and vertically. Their apexes rested on the four piers, to which they conducted the forces of the dome; their sides joined to form arches over openings in the four faces of the cube; and their bases met in a complete circle to form the dome foundation. The pendentive dome could rest directly on this circular foundation or upon a cylindrical wall, called a drum, inserted between the two to increase height.
A History of Architecture on the Comparative Method, by Sir Banister-Fletcher, New York, 1950, pp. 238, 240, 242
The character of Byzantine architecture, which dates from the fourth century to the present day, is determined by the novel development of the dome to cover polygonal and square plans for churches, tombs, and baptisteries.
The practice of placing many domes over one building is in strong contrast to the Romanesque system of vaulted roofs. The change from Roman and Early Christian forms was gradual, but in the course of two centuries the East asserted its influence; and though no exact line separates Early Christian and Byzantine styles, yet the basilican type, inherited from pagan Rome, is characteristic of the former, and the domed type, introduced from the East, of the latter...
The dome, which had always been a traditional feature in the East, became the prevailing motif of Byzantine architecture, which was a fusion of the domical construction with the Classical columnar style. Domes of various types were now placed over square compartments by means of "pendentives," whereas in Roman architecture domes were only used over circular or polygonal structures.
These domes were frequently constructed of bricks or of some light porous stone, such as pumice, or even of pottery, as at S. Vitale, Ravenna.
Byzantine domes and vaults were, it is believed, constructed without temporary support or "centering " by the simple use of large flat bricks, and this is quite a distinct system probably derived from Eastern methods.
Windows were formed in the lower portion of the dome which, in the later period, was hoisted upon a high "drum" - a feature which was still further embellished in the Renaissance period by the addition of an external peristyle.
The grouping of small domes or semi-domes round the large central dome was effective, and one of the most remarkable peculiarities of Byzantine churches was that the forms of the vaults and domes were visible externally, undisguised by any timber roof; thus in the Byzantine style the exterior closely corresponds with the interior.
Examples from Buffalo architecture:
- Illustration above: Our Lady of Victory Basilica
- St. Casimer RC Church
- St. Vincent De Paul RC Church
- Blessed Trinity Church - octagonal
- Our Lady of Lourdes RC Church
- Florence Cathedral, Italy
- St. Paul's Cathedral, London, England
- St. Peter's Basilica, Vatican City, Italy