dome

—domelike, adj.

/dohm/, n., v., domed, doming.

n.

1. Archit.

a. a vault, having a circular plan and usually in the form of a portion of a sphere, so constructed as to exert an equal thrust in all directions.

b. a domical roof or ceiling.

c. a polygonal vault, ceiling, or roof.

2. any covering thought to resemble the hemispherical vault of a building or room: the great dome of the sky.

3. anything shaped like a hemisphere or inverted bowl.

4. (in a dam) a semidome having its convex surface toward the impounded water.

5. Crystall. a form having planes that intersect the vertical axis and are parallel to one of the lateral axes.

6. Geol. upwarp.

7. Also called vistadome. Railroads. a raised, glass-enclosed section of the roof of a passenger car, placed over an elevated section of seats to afford passengers a full view of scenery.

8. Horol. an inner cover for the works of a watch, which snaps into the rim of the case.

9. a mountain peak having a rounded summit.

10. Slang. a person's head: I wish I could get the idea into that thick dome of yours.

v.t.

11. to cover with or as if with a dome.

12. to shape like a dome.

v.i.

13. to rise or swell as a dome.

[1505-15; < MF dome < It duomo < ML domus (Dei) house (of God), church; akin to TIMBER]

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I

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.

II

(as used in expressions)

Dome of the Rock

salt dome

Teapot Dome scandal

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▪ architecture

      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 (Byzantine architecture) 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 (pendentive), inverted triangular masses of masonry curved both horizontally and vertically, as shown in the figure—>. 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.

      Displaced architecturally by the light, vertical styles of Gothic architecture, the dome regained popularity during the European Renaissance and Baroque periods. Vaulting is simpler than doming, and so the effort and ingenuity devoted to doming rectangular structures must be explained principally by the symbolic character of the dome. The desire to observe tradition preserved the dome in the early era of iron and steel construction. The modern reinforced concrete slab used in vaulting can be curved in length as well as width to form a dome. Here the distinction between vaults and domes has lost its original significance, being based only on the type of curvature in the slab.

      The geodesic dome (q.v.) is built up of triangular or polygonal facets that distribute stresses within the structure itself.

▪ geology

 in geology, any large or elliptical structure formed by the fractureless upwarping of rock strata. It is a type of anticline that lacks clear-cut elongation and that slopes outward in all directions from the highest point. Typical examples of such a dome can be found in the Black Hills of South Dakota in the western United States. Where strata plunge more or less uniformly toward surrounding lowlands, erosion may produce a series of concentric ridges with their steep slopes facing inward toward the centre. In some areas domes in which a layer of relatively impermeable shale overlies a layer of permeable sandstone are structural traps for oil and natural gas. The oil and gas migrate upward, becoming trapped against the shale at the uppermost part of such anticlinal formations.

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