Cubit
182358
225735521
2008-07-15T03:53:16Z
76.169.3.13
/* The Egyptian Royal Cubit and Sumerian Nippur cubit */
:''For the multi-touch interface see [[CUBIT (multi-touch)]]. For the unit of information, see [[qubit]]. For the bone, see [[ulna]].''
{{Refimprove|date=February 2008}}
{{Vitruvian_Man_Measurements}}
A '''cubit''' is any one of many units of measure used by various ancient peoples and is among the first recorded units of [[length]].
The cubit is based on measuring by comparing – especially cords and textiles, but also for timbers and stones – to one's forearm length. The Egyptian [[hieroglyph]] for the unit shows this symbol. It was employed consistently through [[classical antiquity|Antiquity]], the [[Middle-Ages]] up to the [[Early modern Europe|Early Modern Times]].
The distance between thumb and another finger to the elbow on an average person measures about 24 digits or 6 palms or 1½ feet. This is about 45 cm or 18 inches. This so-called "natural cubit" of 1½ feet is used in the Roman system of measures and in different Greek systems.
Over time, units similar in type to the cubit have measured:
* 6 palms = 24 digits, i.e. ~45.0 cm or 18 inches (1.50 ft)
* 7 palms = 28 digits, i.e. ~52.5 cm or 21 inches (1.75 ft)
* 8 palms = 32 digits, i.e. ~60.0 cm or 24 inches (2.00 ft)
* 9 palms = 36 digits, i.e. ~67.5 cm or 27 inches (2.25 ft)
From late Antiquity, the Roman ulna, a four-foot cubit (about 120 cm) is also attested. This length is the measure from a man's hip to the fingers of the outstretched opposite arm.
The English [[yard]] could be considered to be a type of cubit, measuring 12 palms, ~90 cm, or 36 inches (3.00 ft). This is the measure from the middle of a man's body to his fingers, always with outstretched arm. The English [[ell]] is essentially a kind of great cubit of 15 palms, 114 cm, or 45 inches (3.75 ft).
== History of the different cubits ==
=== The Egyptian Royal Cubit and Sumerian Nippur cubit ===
[[image:Old Royal Cubit.jpg|thumb|300px|From the Nippur ell to the old royal cubit]]
The cubit is among the first recorded units of [[length]] used by an ancient people.
The earliest attested standard measure was called the '''''Royal Cubit''''' (''Mahe'') and was 523.5 to 524 mm (20.61 to 20.63 inches) in length, and was subdivided into 7 palms of 4 digits, giving a 28 part measure in total. Secure evidence for this unit is known from architecture, from at least as early as the construction of the [[Step Pyramid]] of [[Djoser]] from around 2,700 B.C.
In [[1916]], during the last years of [[Ottoman Empire]] and in the middle of [[World War I|WWI]] the German [[Assyriology|assyriologist]] Eckhard Unger found a copper-alloy bar during excavation at Nippur from c. 2650 BC. which he claimed was a measurement standard. This irregularly formed and irregularly marked ''graduated rule'' supposedly defined the '''''Sumerian cubit''''' as about 518.5 mm or 20.4 inches, although this does not agree with more secure evidence from the statues of Guduea from the same region. A 30-digit-cubit known as ''a kus'' was nevertheless known from the 2nd millennium B.C., with a digit-length of about 17.28 mm (more than 0.68 inch).
Old Egyptian geometers could calculate the [[square root]] of two from the value of the [[hypotenuse]] of a Cubit. This well-attested old Egyptian unit was known as the "construction remen" and used a good approximation: 2×20/28 <small>≥</small> root 2.
=== Other important cubits ===
* The '''''[[Ancient Roman units of measurement|Roman cubitus]]''''' is a six-palm cubit of about 444.5 mm. Twenty-four Roman cubits ≈ thirty-five English feet, so the Roman cubit is about 17.5 inches or 444.5 mm.
* The '''''Greek pechua''''' (πεχυα) was also a 24-digit cubit. So, the Greek '''''kyrenaika cubit''''' measured about 463.1 mm and the Greek '''''metrios cubit''''' about 474.2 mm; respectively roughly 25/24 and 16/15 Roman cubits. Other Greek cubits based on different digit measures of other city-states are less important. The Greek 40-digit-measure, called ''bema,'' corresponds to the Latin ''gradus'', the step or half-a-pace.
* The Arabic '''''Hashimi cubit''''' of about 650.2 mm (25.6 inches) is considered to measure two [[French units of measurement|French feet]]. Since the established ratio between the French and English foot is about 16 to 15, one can give following equation: 5 Hashimi cubits ≈ 10 French feet ≈ 128 English inches. Also the length of 256 Roman cubits and the length of 175 Hashimi cubits are nearly equivalent.
* The '''''guard cubit''''' (Arabic: {{lang|ar|''ammatu rabitu''}}) measured about 555.6 mm; 5/4 of the Roman cubit. ''Therefore:'' 96 guard cubits ≈ 120 Roman cubits ≈ 175 English feet.
* The '''''Arabic nil cubit''''' (or '''''black cubit''')'' measured about 540.2 mm. This means 28 (later called) Greek digits of the "pous of kyrenaika" ≈ 25/24 of a Roman foot or just 308.7 mm. Thus 175 Roman cubits ≈ 144 black cubits.
* The '''''Mesopotamian cubit''''' measured about 533.4 mm, 6/5 Roman cubit. Thus, 20 Mesopotamian cubits ≈ 24 Roman cubits ≈ 35 English feet.
* The '''''Babylonian cubit''''' (or cubit of [[Lagash]]) measured about 496.1 mm. Also a '''''Babylonian trade cubit''''' existed, nine-tenths of the normal cubit, i.e. 446.5 mm. The Babylonian Cubit is fifteen-sixteenths of the royal cubit. 160 Babylonian trade cubits ≈ 144 Babylonian cubits ≈ 135 Egyptian royal cubits. (The royal cubit ≈ 529.2 mm. See above.)
*The '''''Pergamon cubit''''' 520.9 mm or 75/64 of the Roman cubit.
*The '''''Salamis cubit''''' 484.0 mm or 98/90 of the Roman cubit.
*The '''''[[Persians|Persian]] cubit''''' of about 500.1 mm or 9/8 of the Roman cubit, which is also 9/10 of the guard cubit.
* In Izapa, a pre-Columbian Mesoamerican city, the measuring unit was equivalent to about 495 mm, very close to the '''Lagash cubit'''. This is probably a coincidence, since a diffusion of culture from Mesopotamia to [[Mesoamerica]] has not been conclusively demonstrated.
* The different '''''[[Judaism|Jewish]] cubits''''' ({{lang|he|אַמָּה ''ama''}}) are generally borrowed either from Babylonians or Greeks or Romans. In [[ancient Israel]] during the First Temple period, the cubit was 428.1 mm (16.85 in.) (≈ 26/27 Roman cubit). During the Second Temple period, a cubit of about 444.5 mm (17.5 in.) (≈ Roman cubit) was in general use, but in the sacred areas of the temple a special cubit of 437.6 mm seems to have been used instead (≈ 63/64 Roman cubit).<ref>Cf. Biblical Archaeology Review, March-April 1983, and Newsletter and Proceedings of the Society for Early Historical Archaeology, issue 159.)</ref>
==See also==
* [[Hasta (measure)]]
* [[History of measurement]]
* [[Systems of measurement]]
* [[Units of measurement]]
== References ==
* [http://vormetrische-laengeneinheiten.de/index.html Vormetrische Längeneinheiten] by [http://vormetrische-laengeneinheiten.de/html/publikationen.html Rolf C. A. Rottländer], Rottenburg / Köln ''(also see [http://www.google.com/search?hl=en&q=Rolf+Rottl%C3%A4nder&btnG=Google+Search Search-Engine]).''
* [http://www.fig.net/pub/athens/papers/wshs2/WSHS2_1_Lelgemann.pdf Recovery of the Ancient System of Length Units] by [http://www.igg.tu-berlin.de/lelgemann/?L=0 Dieter Lelgemann], former Director of the Institute for Geodesy and Geo-Information Technology, [http://www.tu-berlin.de/eng/index.html TU Berlin].
* [http://www.fig.net/pub/athens/papers/wshs1/WSHS1_1_Lelgemann.pdf On the Ancient Determination of Meridian Arc Length by Eratosthenes of Kyrene] Dieter Lelgemann, WS – History of Surveying and Measurement, Athens, Greece, May 22-27, 2004.
* [http://www.tu-berlin.de/fak1/philosophie/institut/knobloch.htm Knobloch, Eberhard], Dieter Lelgemann und [http://www.igg.tu-berlin.de/fuls/ Andreas Fuls]: "Zur hellenistischen Methode der Bestimmung des Erdumfangs und zur Asienkarte des Klaudios Ptolemaios." published in zfv (Zeitschrift für Geodäsie, Geoinformation und Landmanagment) 128. Jahrgang, Heft 3/2003, S. 211-217.
==Notes==
<references/>
==External links==
{{Wiktionarypar|cubit}}
* [http://hexadecimal.florencetime.net/References_Nippur_cubit.htm Measurements of the Nippur Ell], now in a museum in Istanbul (Turkey).
* [http://www.sciforums.com/showthread.php?t=60710&page=11 SciForums' "Why 432 in an Ancient World" thread, wherein Brendan Bombaci's article "Common Ground: A Dash of Music & an Inch of Sun" purports to explain the archaeoastronomical/fluid-dynamic origin of the Royal and Lunar Cubit, hence also the common day 'inch.']
[[Category:Obsolete units of measure]]
[[Category:Units of length]]
[[Category:Human-based units of measure]]
[[da:Alen]]
[[de:Nippur-Elle]]
[[es:Codo (unidad de longitud)]]
[[fr:Coudée]]
[[he:אמה (מידת אורך)]]
[[ko:큐빗]]
[[it:Cubito]]
[[ja:キュビット]]
[[no:Alen]]
[[pt:Côvado]]
[[sl:Kubit (dolžinska mera)]]
[[sv:Aln]]