View source for Abacus (architecture)

{{Short description|Architecture term for a flat slab forming the uppermost part of a column}}

[[Image:Nouveau Larousse illustré, 1898, I (page 22-1 crop).jpg|thumb|300px|1898 illustration of abacuses of many capitals in various styles]]
In [[architecture]], an '''abacus''' (from the [[Ancient Greek]] {{Lang|grc|ἄβαξ}} ({{Transliteration|grc|ábax}}), {{gloss|slab}}; or [[French language|French]] {{Lang|fr|abaque}}, {{Lang|fr|tailloir}}; {{plural form}}: '''abacuses''' or '''abaci''')<ref name = SOED>{{harvnb|Brown|1993|p=2}}</ref> is a flat slab forming the uppermost member or division of the [[Capital (architecture)|capital]] of a [[column]], above the [[Capital (architecture)|bell]].  Its chief function is to provide a large supporting surface, tending to be wider than the capital, as an [[abutment]] to receive the weight of the [[arch]] or the [[architrave]] above. The diminutive of abacus, '''abaculus''', is used to describe small [[mosaic]] tiles, also called '''abaciscus''' or '''[[tessera]]''', used to create ornamental floors with detailed patterns of chequers or squares in a [[tessellated]] pavement.

== Definition ==
In [[classical architecture]], the shape of the abacus and its edge profile varies in the different [[classical order]]s. In the Greek [[Doric order]], the abacus is a plain square slab without [[molding (decorative)|moulding]]s, supported on an [[Echinus (molding)|echinus]].<ref name=fletcher1>{{harvnb|Cruickshank|1996|p=1713}}</ref> In the Roman and Renaissance Doric orders, it is crowned by a moulding (known as "[[crown molding|crown moulding]]"). In the [[Tuscan order|Tuscan]] and Roman Doric capital, it may rest on a [[Bowtell|boltel]].

In the archaic Greek [[Ionic order]], owing to the greater width of the capital, the abacus is rectangular in plan, and consists of a carved [[ovolo]] moulding.  In later examples, the slab is thinner and the abacus remains square, except where there are angled [[volute]]s, where the slab is slightly curved. In the Roman and Renaissance Ionic capital, the abacus is square with a fillet on the top of an [[ogee]] moulding with curved edges over angled volutes.<ref name=fletcher1/>

[[Image:Abacus architecture.gif|frame|center|Individual sections of the column and as constructed by ancient [[Egyptians]], [[ancient Greece|Greeks]] and [[Ancient Rome|Romans]]]]
In an angular capital of the Greek [[Corinthian order]], the abacus is moulded, its sides are concave, and its angles canted<ref>{{harvnb|Avery|1962|p=1}}</ref> (except in one or two exceptional Greek capitals, where it is brought to a sharp angle); the volutes of adjacent faces meet and project diagonally under each corner of the abacus. The same shape is adopted in the Roman and Renaissance Corinthian and [[Composite order|Composite]] capitals, in some cases with the carved ovolo moulding, [[Annulet (architecture)|fillet]], and [[wikt:cavetto|cavetto]].<ref name=fletcher1/><ref>{{harvnb|Kay|1955|p=1}}</ref>

In [[Romanesque architecture]], the abacus survives as a heavier slab, generally moulded and decorated. It is often square with the lower edge splayed off and moulded or carved, and the same was retained in France during the medieval period; but in England, in [[Early English Period|Early English]] work, a circular deeply moulded abacus was introduced, which in the 14th and 15th centuries was transformed into an octagonal one.

In [[Gothic architecture]], the moulded forms of the abacus vary in shape, such as square, circular, or even octagonal,<ref>{{harvnb|Lagassé|2000|p=1}}</ref> it may even be a flat disk or drum.<ref name=fletcher1/> The form of the Gothic abacus is often affected by the shape of a vault that springs from the column, in which case it is called an [[impost (architecture)|impost block]].

== Indian architecture (''śilpaśāstra'') ==
[[File:Rampurava capital abacus detail.jpg|thumb|300px|Abacus of the [[Rampurva capitals|Rampurva capital]] from the time of Emperor [[Ashoka]], 3rd century BCE, [[India]]]]
In ''[[Shilpa Shastras|śilpaśāstra]]'', the ancient Indian science of sculpture, the abacus is commonly termed as ''phalaka'' (or ''phalakā'').<ref>{{Cite book
  | last = Hardy
  | first = Adam
  | author-link =
  | title = Indian Temple Architecture: Form and Transformation
  | place =
  | publisher = Abhinav Publications
  | year = 1995
  | volume =
  | isbn = 8170173124
  | pages = 56, 390
  | edition =
  | url = https://books.google.com/books?id=aU0hCAS2-08C&q=phalaka+abacus&pg=PA390
  | doi =
  | id =
  }}</ref> It consists of a flat plate and forms part of the standard pillar ([[stambha]]). The ''phalaka'' should be constructed below the ''potikā'' ("bracket"). It is commonly found together with the dish-like maṇḍi as a single unit. The term is found in encyclopedic books such as the ''Mānasāra'', ''Kāmikgāgama'' and the ''Suprabhedāgama''.

==Examples in England==
Early [[Anglo-Saxon architecture|Saxon]] abaci are frequently simply [[wikt:chamfer|chamfered]], but sometimes grooved as in the crypt at [[Repton]] (fig. 1) and in the arcade of the refectory at [[Westminster Abbey]]. The abacus in Norman work is square where the columns are small; but on larger piers it is sometimes octagonal, as at [[Waltham Abbey (abbey)|Waltham Abbey]]. The square of the abacus is often sculptured with [[Ornament (architecture)|ornament]]s, as at the [[Tower of London|White Tower]] and at [[Alton, Hampshire]] (fig. 2). In Early English work, the abacus is generally circular, and in larger work, a group of circles (fig. 4), with some examples of octagonal and square shapes. The mouldings are generally half-rounds, which overhang deep hollows in the capital. In France, the abacus in early work is generally square, as at [[Chateau de Blois]] (fig. 3).<br />
[[Image:abacus1-4.png]]

==Examples in France==
The first abacus pictured below (fig. 5) is decorated with simple mouldings and ornaments, common during the 12th century, in Île-de-France, Normandy, Champagne, and Burgundy regions, and from the choir of [[Vézelay Abbey]] (fig. 6).  Figure 7 shows a circular abacus used at windows in the side chapels of [[Notre Dame de Paris]]. Towards the end of the 13th century, this element decreases in importance—they became short with a narrow profile during the 14th century, and disappeared almost entirely during the 15th century (fig. 8).
<gallery>
Image:Abaque.roman.XIIe.siecle.png|<div style="text-align: center;border:none">Fig. 5</div>
Image:Abaque.eglise.Vezelay.png|<div style="text-align: center;border:none">Fig. 6</div>
Image:Abaque.circulaire.XIIIe.siecle.png|<div style="text-align: center;border:none">Fig. 7</div>
Image:Abaque.XVe.siecle.png|<div style="text-align: center;border:none">Fig. 8</div>
</gallery>

==Sources==
*[[s:en|Wikisource]] has original text related to the [[Encyclopædia Britannica Eleventh Edition]] article: [[s:en:1911 Encyclopædia Britannica/Abacus|Abacus]].

==See also==
* [[Pulvino]]

==Footnotes==
{{reflist}}

==References==
* {{Cite encyclopedia |year=1962 |title=abacus |encyclopedia=The New Century Classical Handbook |publisher=Appleton-Century-Crofts, Inc. |location=New York, NY |editor-last=Avery |editor-first=Catherine A. |lccn=62-10069}}
* {{Cite encyclopedia |year=1993 |title=abacus |encyclopedia=Shorter Oxford English Dictionary on Historical Principles |publisher=Oxford University Press |location=Oxford, UK |url=https://archive.org/details/shorteroxfordeng00will_0 |editor-last=Brown |editor-first=Lesley |edition=5th |volume=2: A-K |isbn=978-0-19-860575-1 |url-access=registration}}
* {{Cite book |last=Cruickshank |first=Dan |title=[[Sir Banister Fletcher's A History of Architecture]] |publisher=Architectural Press |year=1996 |isbn=0-7506-2267-9 |editor-last=Fletcher |editor-first=Banister |edition=20th |editor-last2=Saint |editor-first2=Andrew |editor-last3=Frampton |editor-first3=Kenneth |editor-last4=Jones |editor-first4=Peter Blundell}}
* {{Cite book |year=1955 |title=The Modern Building Encyclopaedia: An Authoritative Reference to All Aspects of the Building and Allied Trades |publisher=Philosophical Library |location=New York, NY |editor-last=Kay |editor-first=N. W. |lccn=55013816}}{{full citation needed|date=May 2024}}
* {{Cite encyclopedia |year=2000 |title=abacus |encyclopedia=The Columbia Encyclopedia |publisher=Columbia University Press |location=New York, NY |url=https://archive.org/details/columbiaencyclop00laga |editor-last=Lagassé |editor-first=Paul |edition=6th |isbn=0-7876-5015-3 |lccn=00-027927 |url-access=registration}}

==External links==
*[https://penelope.uchicago.edu/Thayer/E/Roman/Texts/secondary/SMIGRA*/Abacus.html#1 Abacus], Smith's Dictionary of Greek and Roman Antiquities

{{DEFAULTSORT:Abacus (Architecture)}}
[[Category:Columns and entablature]]
[[Category:Architectural elements]]