Squinch

Squinches supporting a dome in Odzun Basilica, Armenia, early 8th century

A squinch is a structural element in architecture used to support the base of a circular or octagonal dome that surmounts a square-plan chamber. Squinches are placed to diagonally span each of the upper internal vertices (corners) where the walls meet. This placement distributes the load of the dome's weight, while also providing a visual bridge from circular to angular building elements. They have several forms.

Squinches originated in the Sasanian Empire of Ancient Persia, and have remained in use across Central and West Asia into modern times. From their Sassanid origin, they influenced Islamic architecture and were inherited by Georgian and Armenian building traditions. Domes built in the Roman-influenced world utilised separately-evolved construction methods, notably the pendentive, which performs a similar function.

Form

Squinches are designed to evenly spread the load of a dome across the intersecting walls on which they rest, thus avoiding concentrating higher structural stress on smaller load-bearing areas. By bridging corners, they also visually transition an angular space (the corners), to a round or near-circular zone (the dome). Constructed from masonry, they have several forms. These include: a graduated series of stepped arches; a hollow, open half-cone, somewhat like half of a funnel laid horizontally – sometimes called a "trumpet arch"; or a small half-dome niche.

History

From its pre-Islamic origin, the squinch developed into an influential structure for Islamic architecture. The architecture of Georgia and Armenia also inherited the form from the Sasanians: squinches were widely employed in buildings of all kinds in these regions. They are heavily featured in surviving or ruined medieval Christian churches of the region. An alternative approach to the structural problem of translating square space to round superstructure is the pendentive, much used in late Roman Empire and Byzantine architecture.

Western Asia

The dome chamber in the Palace of Ardashir, the Sasanian king, in Firuzabad, Iran, is the earliest surviving example of the use of the squinch. After the rise of Islam, it remained a feature of Islamic architecture, especially in Iran, and was often covered by corbelled stalactite-like structures known as muqarnas. It was used in West Asia and North Africa, and in eastern Romanesque architecture, although pendentives are more common in Byzantine architecture. The Hagia Sophia features both squinches and pendentives, in combination.

Western Europe

The feature spread to the Romanesque architecture of western Europe. The earliest squinch still extant in Europe is the 5th-century Baptistery of San Giovanni in Fonte, Naples. A later example is the 12th-century Norman church of San Cataldo, Palermo, in Sicily. This has three domes, each supported by four doubled squinches.

Etymology

The word may possibly originate, the Oxford English Dictionary suggests, from the French word escoinson, meaning "from an angle", which became the English word "scuncheon" and then "scunch".

See also

References

  1. ↑ Webster's Ninth New Collegiate Dictionary, 1986, p. 1145
  2. 1 2 3 4
  3. 1 2 O'Kane, Bernard (15 December 1995) [Updated 27 February 2013]. "Domes". Encyclopaedia Iranica. Vol. VII (Online ed.). Encyclopaedia Iranica Foundation. Fasc. 5, pp. 479–485.
  4. 1 2 Huff, D. (15 December 1986) [Updated 11 August 2011]. "Architecture iii. Sasanian Period". Encyclopaedia Iranica. Vol. II (Online ed.). Encyclopaedia Iranica Foundation. Fasc. 3, pp. 329–334.
  5. ↑ "trumpet arch". Merriam-Webster.com Dictionary. Merriam-Webster. OCLC 1032680871.
  6. 1 2 Golzari, Elaheh; Rabb, Péter (26 September 2022). "Revisiting the Geometry of the Transition Zone Using Filposh Squinches in Ardeshir Palace". Építés – Építészettudomány. 50 (3–4): 351–364. doi:10.1556/096.2022.00079. ISSN 1588-2764.
  7. 1 2 Khoshtaria, David (January 2016). "The Squinch in the Architecture of the Caucasus". In Robert Ousterhout; Dorian Borbonus; Elisha Dumser (eds.). Against Gravity: Building Practices in the Pre-industrial World. Against Gravity: Building Practices in the Pre-industrial World, March 20–22, 2015; Center for Ancient Studies. University of Pennsylvania, School of Arts and Sciences.
  8. ↑ Labisi, Giuseppe (2 July 2020). "Squinches and Semi-domes between the Late Sasanian and Early Islamic Periods". Iran. 58 (2): 236–249. doi:10.1080/05786967.2019.1633241.
  9. ↑ Kula, Seda (January 2012). A Survey and Forms Catalogue for Dome and Transitional Element Usage in the Early Ottoman Architecture. Domes in the World Congress, Florence – March 2012.
  10. ↑ Dalton, O. M. (1925). "The Penditive and Squinch". East Christian Art: A Survey of the Monuments (New York: Hacker Art Books; 1975 facsimile ed.). Oxford: Clarendon Press. pp. 85–87. [Ormonde Maddock Dalton]. p. 86:  ... the squinch was the earliest method employed in Armenia; and its appearance in a domed building over a square plan as far east as Chinese Turkestan (Turfan), which dates from the eighth century at latest, supports [the] ... contention that it is an indigenous Asiatic invention, employed from the first in the domed Iranian dwellinghouse, which is still erected in almost its primitive form to-day. ISBN 978-0-87817-135-4.
  11. ↑

Further reading