Definitions

dome

dome

[dohm]
dome, a roof circular or (rarely) elliptical in plan and usually hemispherical in form, placed over a circular, square, oblong, or polygonal space. Domes have been built with a wide variety of outlines and of various materials.

Early Domes

The earliest domes were probably roofed primitive huts and consisted of bent-over branches plastered with mud. Another primitive form, called a beehive dome, is constructed of concentric rings of corbeled stones and has a conical shape. Ancient examples have been found in the tombs of Mycenae and can also still be seen in the folk architecture of Sicily. Although there is evidence of widespread knowledge of the dome, its early use was apparently restricted to small structures built of mud brick.

Roman and Byzantine Domes

It was the Romans who first fully realized the architectural potentialities of the dome. The Roman development in dome construction culminated in the pantheon (2d cent. A.D.). The Romans, however, failed to discover a proper handling of the pendentive—the device essential to placing a dome over a square compartment—that was finally achieved by the Byzantine builders of Hagia Sophia at Constantinople (A.D. 532-37). The other solution to placing a dome over a square was the squinch, which in the form of stalactites was to receive superb expression in Islamic architecture. Under Byzantine influence the Muslims early adopted the use of the dome; one of their first important monuments is the Dome of the Rock in Jerusalem. They often used the so-called Persian or onion dome. The most celebrated example is the Taj Mahal (A.D. 1630) at Agra, India.

Renaissance Refinements

Both the influence of the Roman Pantheon and of the Byzantine pendentive came to bear on the designers of the Italian Renaissance, and the crossings of many churches of the period were covered by masonry domes on pendentives. Between pendentive and dome a circular drum usually was interposed, serving to give greater elevation and external importance as well as a space for the introduction of windows. By the addition of an outer shell, the exterior came to be independently designed for maximum effectiveness, and the placing of a lantern at the top of this outer shell provided an apex for the entire composition.

Modern Domes

The dome in modern architecture utilizes such materials of construction as reinforced and thin-shell concrete, glass and steel, and plastic. An innovative contemporary approach to the form is the geodesic dome. These are low-cost, geometrically determined hemispherical forms as promoted by architect Buckminster Fuller.

Outstanding Domes

Celebrated examples are Brunelleschi's octagonal ribbed dome for the Cathedral of Florence (1420-36); St. Peter's, Rome, designed by Michelangelo, with two masonry shells (completed 1590), internal diameter 137 ft (42 m); the church of the Invalides, Paris, by J. H. Mansart (1706), 90 ft (27 m); St. Paul's Cathedral, London, by Sir Christopher Wren (1675-1710), 112 ft (34 m); and the Panthéon, Paris, by J. G. Soufflot (1775-81), 69 ft (21 m). The last three domes are built with triple shells, the middle shells serving to support the crowning lanterns.

In the United States the dome of the Massachusetts state capitol, designed (1795) by Charles Bulfinch, established the dome as a distinctive feature for numerous later state capitols as well as for the national Capitol at Washington, D. C. The dome of the latter, however, is of cast iron instead of masonry. The design, by T. U. Walter, has an inner diameter of 90 ft (27 m) and possesses great external impressiveness.

Bibliography

See E. B. Smith, The Dome: A Study in the History of Ideas (1975).

Largely subsurface geologic structure that consists of a vertical cylinder of salt embedded in horizontal or inclined strata. In the broadest sense, the term includes both the core of salt and the strata that surround and are “domed” by the core. Major accumulations of oil and natural gas are associated with salt domes in the U.S., Mexico, the North Sea, Germany, and Romania; domes along the Gulf Coast contain large quantities of sulfur. Salt domes are also major sources of salt and potash on the Gulf Coast and in Germany, and they have been used for underground storage of liquefied propane gas. Storage “bottles,” made by drilling into the salt and then forming a cavity by subsequent solution, have been considered as sites for disposal of radioactive wastes.

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A dome is traditionally supported primarily by a cylindrical or polygonal drum; it may be elipsis

In architecture, a hemispherical structure evolved from the arch, forming a ceiling or roof. Domes first appeared on round huts and tombs in the ancient Middle East, India, and the Mediterranean in forms, such as solid mounds, adaptable only to the smallest buildings. The Romans introduced the large-scale masonry hemisphere. A dome exerts thrust all around its perimeter, and the earliest monumental examples (see Pantheon) required heavy supporting walls. Byzantine architects invented a technique for raising domes on piers, making the transition from a cubic base to the hemisphere by four pendentives. Bulbous or pointed domes were widely used in Islamic architecture. The design spread to Russia, where it gained great popularity in the form of the onion dome, a pointed, domelike roof structure. The modern geodesic dome, developed by R. Buckminster Fuller, is fabricated of lightweight triangular framing that distributes stresses within the structure itself.

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or Mosque of Omar

Oldest existing Islamic monument. It is located on Temple Mount, previously the site of the Temple of Jerusalem. The rock over which it is built is sacred to both Muslims and Jews. In Islam, Muhammad is believed to have ascended into heaven from the site. In Judaism it is the site where Abraham prepared to sacrifice his son Isaac. Built in 685–91 as a place of pilgrimage, the octagonal building has richly decorated walls and a gold-overlaid dome mounted above a circle of piers and columns.

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A dome is a common structural element of architecture that resembles the hollow upper half of a sphere.

Description

Domes do not have to be perfectly spherical in cross-section, however; a section through a dome may be an ellipse. If the baseline is taken parallel to the shorter of an ellipse's two diameters, a tall dome results, giving a sense of upward reach. A section across the longer axis results in a low dome, capping the volume instead. A very low dome is classified as a saucer dome. All the surfaces of any dome are curved. A spectacular innovation, one that is at the heart of Baroque style, is the oval dome, which gives axial direction and movement to the space beneath it. Though the oval dome is typically identified with churches of Bernini and Borromini, the first oval dome was erected by Vignola for a chapel, Sant'Andrea in Via Flaminia often called Sant'Andrea del Vignola. Julius III commissioned the dome in 1552 and construction finished the following year. The largest oval dome was built in the basilica of Vicoforte by Francesco Gallo.

Domes that have been disproportionately influential in later architecture are those of the Pantheon in Rome, Hagia Sophia in Istanbul (or in that time Constantinople), and the Dome of the Rock in Jerusalem. In Western architecture, the most influential domes built since the Renaissance have been those of St. Peter's Basilica in Rome and Jules Hardouin-Mansart's dome at Les Invalides in Paris. The dome of St. Paul's Cathedral in London was the inspiration for the United States Capitol in Washington, which in turn inspired domes of most of the US state capitols.

A cathedral is often referred to as a duomo in Italian or "dom" in German. This is not because so many are crowned with crossing domes over the space where transepts intersect the nave, but instead stemming from the Latin noun "domus", house, or in this case the "domus dei", the house of God. A dome is a mark of palatial ambitions whenever it is seen crowning a residence. The first residential domes were seen in Nero's Domus Aurea that covered the slope of the Palatine Hill, built after the Great Fire of Rome of AD 64 with a lavishness that scandalized the senatorial class.

In the 20th century, thin "eggshell" domes of pre-stressed concrete by architect-engineers such as Nervi opened new directions in fluid vaulted spaces enclosed beneath freeform domed space which now might be supported merely at points rather than in the traditional constricting ring.

Characteristics

A dome can be thought of as an arch which has been rotated around its vertical axis. As such, domes have a great deal of structural strength. A small dome can be constructed of ordinary masonry, held together by friction and compressive forces. Larger domes built after Brunelleschi's dome that triumphantly spanned the crossing of Santa Maria del Fiore, the duomo of Florence, have all been built as double domes, with inner and outer shells.

A dome can sit directly on a circular base, however, this is not possible if the base is square. The concave triangular or trapezoidal sections of vaulting that provide the transition between a dome and the square base on which it is set and transfer the weight of the dome are called pendentives. (A less sophisticated version of a pendentive is a squinch.) Under the dome illustrated at left, the pendentives bear circular medallions in bas relief. A pendentive is a constructive device permitting the placing of a circular dome over a square room or an elliptical dome over a rectangular room. The pendentives, which are triangular segments of a sphere, taper to points at the bottom and spread at the top to establish the continuous circular or elliptical base needed for the dome. In masonry the pendentives thus receive the weight of the dome, concentrating it at the four corners where it can be received by the piers beneath. Prior to the pendentive's development, the device of corbelling or the use of the squinch in the corners of a room had been employed. The first attempts at pendentives were made by the Romans, but full achievement of the form was reached only by the Byzantines in Hagia Sophia at Constantinople (6th cent.). In the simple dome the pendentives are part of the same sphere as the dome itself, however such domes are rare. In the more common compound dome the pendentives are part of the surface of a sphere of larger radius than the dome itself but whose center is at a point lower than that of the dome. Another alternative is for a drum to be inserted between the dome and pendentives. Pendentives were commonly used in Byzantine, Renaissance and baroque churches.

A half-dome forms the head of an exedra or its smaller version, a niche. In Late Antiquity, the exedra developed into the apse, with separate developments in Romanesque and Byzantine practice.

Many domes are topped by a lantern, a structure with openings (or windows) to admit light in the cupola.

Many sports stadiums are domed, especially in climates that have widely-variable summer and winter weather. The first such stadium was the Astrodome in Houston, Texas. A major improvement to the domed stadium was accomplished with the construction of SkyDome, now Rogers Centre, in Toronto, Ontario, the first domed stadium with a retractable roof.

Saucer dome

A saucer dome is the architectural term used for a low pitched shallow dome which is described geometrically as having a circular base and a segmental (less than a semicircle) section. A section across the longer axis results in a low dome, capping the volume. A very low dome is a saucer dome. Many of the largest existing domes are of this shape.

Gaining in popularity from the 18th century onwards, the saucer dome is often a feature of interior design. When viewed from below it resembles the shallow concave shape of a saucer. The dome itself, being often contained in the space between ceiling and attic, is invisible externally. These domes are usually decorated internally by ornate plaster-work, occasionally they are frescoed.

They are seen occasionally externally in Byzantine churches and mosques. Most of the mosques in India, Pakistan, Iran and Afghanistan have these type of domes.

Onion dome

The onion dome resembles more than half of a sphere, exemplified by Saint Basil's Cathedral in Moscow and the Taj Mahal. They are found mostly in eastern architecture, particularly in Russia, Turkey, India, and the Middle East. An onion dome is a type of architectural dome usually associated with Russian Orthodox churches. Such a dome is larger in diameter than the drum it is set upon and its height usually exceeds its width. These bulbous structures taper smoothly to a point, and strongly resemble the onion, after which they are named.

Domes in buildings of worship

Domes also play a very important part in places of worship where they can represent and symbolise different aspects of the religion. Eastern orthodox churches, for example, have domes which represent heaven. The dome's purpose is to remind people that to gain God's blessing it is necessary to accept salvation through Christ. Domes can also be found in Islamic places of worship, called mosques. In an orthodox church the domes have pictures of Jesus whereas in Islam it is forbidden during worship. Instead, mosques have decorations and patterns on the domes. The domes are tradition in Islam, and another reason for domes is so that the building can be distinguished and others can see where it is even from far.

Cupola

A cupola is a dome-shaped ornamental structure located on top of a larger roof or dome, often used as a lookout or to admit light and provide ventilation. The word derives from the lower Latin cupula (classical Latin cupella from the Greek kupellon), small cup, indicating a vault resembling an upside-down cup.

Famous domes

Listed in order of their completion:

Xanadu House

The Xanadu House was a home that used the concept of domes heavily in its shape and design. The home was one of the first non-indigenous homes to use curved surfaces throughout the exterior and interior.

See also

External links

References

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