ancientegyptiancubit

Ancient Egyptian Cubit

The determinative and ideogram in mH, 'cubit' is the 'forearm with palm down' sign, D42. The main subdivisions of the cubit were the palm (Szp, 1/7 of a cubit), represented by the 'hand without thumb' sign (D48), and the 'finger' (Dba, 1/28 of a cubit) represented by the 'finger' sign (D50).

Ideogram for 'measure' - 'forearm with stick' sign, D40.

The 'measuring rod' (mAt), U1 (mA) + X1 (t) + det. T20 (Faulkner 2002 (1962): 102) was an important measuring tool in the Old Kingdom - the 'overseer of builders' had someone to carry his measuring rod for him. When his brother was appointed 'overseer of builders' (imy-rA qdw), Nekhebu who had been his brothers personal scribe or secretary, carried his measuring rod (mAt). (GM 7 2000: 32)

Early examples of D42 ('cubit') in Old Kingdom texts:

200 cubits, D42 + V1a 'coil of rope' (ideo. for 100) repeated twice - from the early Dyn 4 tomb of Metjen:

30 cubits, D42 + V20 'fetter' (ideo. for 10) repeated three times:

Length of cubit

As no cubit rods have survived in the archaeological record from the Old Kingdom (OK), the length of the OK cubit is determined by analyzing measurements taken from the royal funerary complexes, and comparing these with cubit rods from a later period.

Based on his extensive surveys, Petrie's estimate for the original length of the cubit in the OK was 523.7mm (20.62") - to the nearest millimeter, 524mm. "On the whole we may take 20.62 ± .0I as the original value, and reckon that it slightly increased on an average by repeated copyings in course of time." (Petrie 1883: 181)

A 2 cubit long wooden working rod in the British Museum is 1.0489m, or 2 x 0.52445m (to the nearest mm, 524mm), that demonstrates remarkable consistency in maintaining a standard linear unit over long periods of time, but course it cannot be compared to modern day standards where since 1983, the metre is defined by the International Bureau of Weights and Measures as the distance traveled by light in absolute vacuum in 1/299,792,458 of a second.

According to Petrie's survey data, the most likely length of the cubit used for the three main pyramids at Giza, is ~524 mm. (to the nearest millimetre: G1 = 524 mm; G2 = 524 mm; G3 = 526 mm). 524 mm is also the mean length of the cubit from Dyn 4 to Dyn 6, with an average variation of 1.5 mm. (Petrie 1883: 179)

Surveys of the pyramids in their now ruinous state will inevitably produce apparent variations in a standard cubit. The variations found by Petrie are to within tolerances normally found in building construction. Apparent variations do not necessarily mean the AE had various standard lengths for the cubit - the builders were not working to engineering tolerances but to building construction tolerances where specified lengths realized on site can slightly differ from the length specified by the architect - a passageway designed to be 2 cubits wide, might be 2 cubits and a bit more or less depending on the builder's / mason's ability, and the quality of supervision.

Origin of the ~524mm cubit

"The Ibis reveals Thoth's creative powers. The step of the bird is said to measure one cubit (Aelian, Nat. anim. 10.29) and the spreading of the legs formed an equilateral triangle. (Plutarch, de Isid. et Osirid. 381D, Quaest. coniv. 670C; compare the white triangle on Apis's brow). The cubit was sacred to Thoth and by means of it the god measured the cosmos and its counterpart Egypt, thus establishing the cosmic order (Eg Maat)." ('Dictionary of deities and demons in the Bible' K. van der Toorn, B. Becking, P.W. van der Horst 1995: 444)

A king depicted on a an Early / Pre-Dynastic macehead, has his right arm horizontal along the end of a hoe, grasping it with his hands. His right arm is similar to the the 'forearm' sign

An early Dyn 5 scene of king Sahura standing before two deities, Khnum and Nekhbet. The dieties are of a much larger stature than the king, so the length of the forearms is also longer, which may partly explain why a 524 mm cubit is somewhat longer than the average male forearm - it was a 'divine' cubit.

Division of Cubit

According to the remains of a Dyn 1 to 5 annalistic record (Palermo Stone), the cubit was divided into more than 6 palms as early as the Early Dynastic period, which makes it highly likely the cubit originally had 7 palms with each palm divided into 4 fingers. The AE measured the heights of the Nile down to 2/3 and 1/4 of a finger, which implies the finger was subdivided into at least 12 parts.

A New Kingdom cubit rod of Amenhetep I (1525 - 1504) is 523.5 mm long, with 28 main divisions, 15 of which are divided into 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and 16 parts. With this cubit rod, it was possible to accurately measure down to ~1 mm, the smallest linear unit used in modern architecture.

Chris Tedder, Summer 2008