A keystone (or capstone) is the wedge-shaped stone at the apex of a masonry arch or typically round-shaped one at the apex of a vault. In both cases it is the final piece placed during construction and locks all the stones into position, allowing the arch or vault to bear weight.[1][2][3] In arches and vaults (such as quasi-domes) keystones are often enlarged beyond the structural requirements and decorated. A variant in domes and crowning vaults is a lantern.
The keystone (shown in red) of an archDropped keystone at Colditz Castle
Keystones, as a hallmark of strength or good architecture, or their suggested form are sometimes placed in the centre of the flat top of doors, recesses and windows for decorative effect, so as to form an upward projection of a lintel.
Although a masonry arch or vault cannot be self-supporting until the keystone is placed, the keystone experiences the least stress of any of the voussoirs, due to its position at the apex.[citation needed] Old keystones can decay due to vibration, a condition known as bald arch.
In a rib-vaulted ceiling, keystones commonly mark the intersections of any two or more arched ribs. For aesthetics, keystones are often larger than ribs in vaults and many of the voussoirs (arch stones) in arches, or embellished with a boss.
A "dropped keystone" is one where the keystone projects lower than the other voussoirs. Following Giulio Romano, Mannerist architects of the 16th century often designed arches with enlarged and slightly dropped keystones, as in the "church house" entrance portal at Colditz Castle. Numerous examples are found in the work of Sebastiano Serlio, a 16th-century Italian Mannerist architect.
Metaphor
Keystone is often used metaphorically for an essential part on which the whole depends.
The U.S. state of Pennsylvania calls itself the "Keystone State", because during early American history, it held a crucial central position among the Thirteen Colonies geographically, economically, and politically, like the keystone in an arch.[4] A keystone is a symbol of Pennsylvania, being used in the logos of many Pennsylvania government departments, in Pennsylvania state route signs, and on Pennsylvania car license plates, and the Shoulder Sleeve Insignia of the Pennsylvania National Guard's 28th Infantry Division (United States), a Red Keystone, first adopted in WWI in October 1918.
keystone, architecture, this, article, about, architectural, element, other, uses, keystone, disambiguation, keystone, capstone, wedge, shaped, stone, apex, masonry, arch, typically, round, shaped, apex, vault, both, cases, final, piece, placed, during, constr. This article is about the architectural element For other uses see Keystone disambiguation A keystone or capstone is the wedge shaped stone at the apex of a masonry arch or typically round shaped one at the apex of a vault In both cases it is the final piece placed during construction and locks all the stones into position allowing the arch or vault to bear weight 1 2 3 In arches and vaults such as quasi domes keystones are often enlarged beyond the structural requirements and decorated A variant in domes and crowning vaults is a lantern The keystone shown in red of an archDropped keystone at Colditz CastleKeystones as a hallmark of strength or good architecture or their suggested form are sometimes placed in the centre of the flat top of doors recesses and windows for decorative effect so as to form an upward projection of a lintel Although a masonry arch or vault cannot be self supporting until the keystone is placed the keystone experiences the least stress of any of the voussoirs due to its position at the apex citation needed Old keystones can decay due to vibration a condition known as bald arch Contents 1 Architecture 2 Metaphor 3 Gallery 4 See also 5 Notes 6 External linksArchitecture EditIn a rib vaulted ceiling keystones commonly mark the intersections of any two or more arched ribs For aesthetics keystones are often larger than ribs in vaults and many of the voussoirs arch stones in arches or embellished with a boss A dropped keystone is one where the keystone projects lower than the other voussoirs Following Giulio Romano Mannerist architects of the 16th century often designed arches with enlarged and slightly dropped keystones as in the church house entrance portal at Colditz Castle Numerous examples are found in the work of Sebastiano Serlio a 16th century Italian Mannerist architect Metaphor EditKeystone is often used metaphorically for an essential part on which the whole depends The U S state of Pennsylvania calls itself the Keystone State because during early American history it held a crucial central position among the Thirteen Colonies geographically economically and politically like the keystone in an arch 4 A keystone is a symbol of Pennsylvania being used in the logos of many Pennsylvania government departments in Pennsylvania state route signs and on Pennsylvania car license plates and the Shoulder Sleeve Insignia of the Pennsylvania National Guard s 28th Infantry Division United States a Red Keystone first adopted in WWI in October 1918 Gallery Edit Keystone from the palazzo Borgazzi Milan Italy Keystone much enlarged for decorative effect and carrying a coat of arms Barcelona The York Minster Chapter House rib vault ceiling with central and peripheral keystones A boss depicting Jesus Christ decorates the keystone in the rib vaulting at Chapel of St Anne in Malbork 14th century Bossed keystone in the ceiling of an apse chapel Toulouse Cathedral Horseshoe arches with equal size voussoirs and keystones Mosque Cathedral of Cordoba Spain Main entrance Giusti s Palace Keystone with rustic quoins and face of man Dropped keystone on a German church Doors and windows with decorated keystones Munich A range of plain but enlarged keystones by Giulio Romano for his house in Mantua The keystone is the symbol of the Order of Mark Master Masons As a metaphor the navicular bone shown in green is known as the keystone of the foot 5 See also EditArchitectural sculpture Coping architecture List of classical architecture terms Oculus compression ringNotes Edit Ching Francis D K 1995 A Visual Dictionary of Architecture New York John Wiley amp Sons Inc p 12 ISBN 0 471 28451 3 Glossary of Medieval Art and Architecture Keystone University of Pittsburgh Retrieved 2007 06 25 keystone Merriam Webster Retrieved 2007 06 25 State Symbols PA gov Commonwealth of Pennsylvania Retrieved 2020 07 02 UpToDate www uptodate com Retrieved 2022 06 11 External links Edit Wikisource has the text of the 1911 Encyclopaedia Britannica article Keystone Media related to keystones at Wikimedia Commons Retrieved from https en wikipedia org w index php title Keystone architecture amp oldid 1152191156, wikipedia, wiki, book, books, library,
