squinch

{{Short description|Architectural element used to support a dome}}

{{About|an architectural feature|square-inch analysis|Square-inch analysis}}

{{Use dmy dates|date=December 2024}}

File:Odzun cupola.jpg, Armenia, early 8th century]]

In architecture, a squinch is a structural element used to support the base of a circular or octagonal dome that surmounts a square-plan chamber.Webster's Ninth New Collegiate Dictionary, 1986, p. 1145 Squinches are placed to diagonally span each of the upper internal corners (vertices) where the walls meet. Constructed from masonry, they have several forms, including a graduated series of stepped arches; a hollow, open half-cone (like half of a funnel laid horizontally); or a small half-dome niche. They are designed to evenly spread the load of a dome across the intersecting walls on which it rests, thus avoiding concentrating higher structural stress on smaller load-bearing areas. By bridging corners, they also visually transition an angular space to a round or near-circular zone.

Squinches originated in the Sassanid Empire of Ancient Persia, remaining in use across Central and West Asia into modern times. From its pre-Islamic origin, it developed into an influential structure for Islamic architecture.{{cite journal |last1=Labisi |first1=Giuseppe |title=Squinches and Semi-domes between the Late Sasanian and Early Islamic Periods |journal=Iran |date=2 July 2020 |volume=58 |issue=2 |pages=236–249 |doi=10.1080/05786967.2019.1633241}}{{multiref2|1={{cite magazine |last1=Cresswell |first1=K. A. C. |title=Persian Domes Before 1400 AD |date=January 1915 |publisher=Burlington Magazine Publications, Ltd |location=London |pages=146–155 |volume=26 |issue=142 |magazine=The Burlington Magazine for Connoisseurs |ref=none |JSTOR=859853 |url= https://archive.org/details/burlingtonmagazi26londuoft/page/146/mode/2up }}

|2={{cite magazine |author-mask=2 |last1=Cresswell |first1=K. A. C. |title=Persian Domes Before 1400 AD: Conclusion |date=February 1915 |publisher=Burlington Magazine Publications, Ltd |location=London |pages=208–213 |volume=26 |issue=143 |magazine=The Burlington Magazine for Connoisseurs |url=https://archive.org/details/burlingtonmagazi26londuoft/page/208/mode/2up |JSTOR=859962 |ref=none}} }}{{cite encyclopaedia |last1=O'Kane |first1=Bernard |author1-link=Bernard O'Kane (scholar) |title=Domes |date=15 December 1995 |publisher=Encyclopaedia Iranica Foundation |volume =VII |at=Fasc. 5, pp.{{nbsp}}479–485 |edition=Online |url=https://iranicaonline.org/articles/domes |encyclopaedia=Encyclopaedia Iranica |orig-date=Updated 27 February 2013}} Georgia and Armenia also inherited the form from the Sassanids, where squinches were widely employed in buildings of all kinds. They are heavily featured in surviving or ruined medieval Christian churches of the region.{{cite conference |last1=Khoshtaria |first1=David |title=The Squinch in the Architecture of the Caucasus|date=January 2016 |conference =Against Gravity: Building Practices in the Pre-industrial World, March 20–22, 2015; Center for Ancient Studies |publisher=University of Pennsylvania, School of Arts and Sciences |book-title =Against Gravity: Building Practices in the Pre-industrial World |editor1= Robert Ousterhout|editor2= Dorian Borbonus|editor3= Elisha Dumser|url= https://www.sas.upenn.edu/ancient/publications.html}} 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.{{cite conference |last1=Kula |date= January 2012 |first1=Seda |title=A Survey and Forms Catalogue for Dome and Transitional Element Usage in the Early Ottoman Architecture|conference=Domes in the World Congress, Florence – March 2012 |url=https://www.academia.edu/76910387/A_Survey_and_Forms_Catalogue_for_Dome_and_Transitional_Element_Usage_in_the_Early_Ottoman_Architecture}} Domes built in the Roman-influenced world utilised separately-evolved construction methods.{{r|kane|huff}}

File:Squinch.jpg in Fars province, Iran]]