Cubit

Cubit is the name for 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 rope and textiles, but also for timber and stone – to one's forearm length. The Egyptian hieroglyph for the unit shows this symbol. It was used through antiquity, the Middle Ages up to early modern times.

The distance between thumb and another finger to the elbow on an average person is about 24 digits or 6 palms or 1½ feet (45.72 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-feet-cubit (about 120 cm) is also known. This is the measure from a man's hip to the fingers of the outstretched opposite arm.

The English yard has a long legal history, but its origin is not known. The English ell is essentially a kind of great cubit of 15 palms, 114 cm, or 45 inches (3.75 ft).

Related pages
 Units of measurement

 References 

 Recovery of the ancient system of length units by Dieter Lelgemann , former Director of the Institute for Geodesy and Geo-Information Technology, TU Berlin .
 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.

 Other websites 
 Measurements of the Nippur Ell, now in a museum in Istanbul (Turkey).

Category:Units of length