Extract from Wikipaedia on Roman linear and area measures.
Length
Modern metrologists have found the Roman foot to be 16⁄28 of the Nippur cubit.
| Roman unit | Latin name | Feet | Equivalence |
|---|---|---|---|
| one digit | digitus | 1⁄16 | 18.5 mm |
| one inch | uncia | 1⁄12 | 24.6 mm |
| one palm | palmus | 1⁄4 | 74 mm |
| one foot | pes | 1 | 296 mm |
| one cubit | cubitus | 1 |
444 mm |
| one step | gradus | 2 |
0.74 m |
| one pace | passus | 5 | 1.48 m |
| one perch | pertica | 10 | 2.96 m |
| one arpent | actus | 120 | 35.5 m |
| one stadium | stadium | 625 | 185 m |
| one mile | milliarium | 5000 | 1.48 km |
| one league | leuga | 7500 | 2.22 km |
Notes
- From late Antiquity the Roman foot was sometimes divided into unciae comprising 12 equal parts.
The ancient digit measure, however, largely dominated before the beginning of the Middle Ages. - The value of the historical Roman foot scientifically obtained through modern statistical methods is 296.2 mm ± 0.5 mm, or about (296.2 ±0.17%) mm (cf. Rottländer, Tübingen, Germany). The table above is based on this value, but rounded to the millimetre precision for the foot.
- The widely accepted ratio between the Roman foot and the English foot is 36:35. The latter one is 16/28 Mesopotamian cubit and the ratio between this one and the Roman cubit is 20:24. If the present English foot is taken as for reference, the Roman foot should be 296 1/3 mm. That is within the margin obtained by R.C.A. Rottländer (see references).
- A Roman foot can be visualised as being approximately equal to the height of an A4 sheet of paper. This comparison, although descriptive, is +0.27% out of the range given above.
[edit] Area
| Roman unit | Latin name | Acres | Equivalence |
|---|---|---|---|
| one square foot | pes quadratus | 1⁄14 400 | ~ 876 cm² |
| one square perch | scripulum | 1⁄144 | ~ 8.76 m² |
| one aune of furrows | actus minimus | 1⁄30 | ~ 42 m² |
| one rood | clima | 1⁄4 | ~ 315 m² |
| one acre | actus quadratus also known as acnua |
1 | ~ 1260 m² |
| one yoke | iugerum | 2 | ~ 2520 m² |
| one morn | heredium | 4 | ~ 5040 m² |
| one centurie | centurium | 400 | ~ 50.5 ha |
| one “quadruplex” | saltus | 1600 | ~ 201.9 ha |
The Roman acre is the squared Roman arpent, 120 pedes by 120 pedes. This equals 14 400 square feet or about 0.126 hectares.
The Romans also had a unit of area called a quinaria, which was used to measure the cross-sectional area of pipes. One quinaria was considered to be roughly 4.2 cm².
Note: Some researchers assert that the Roman surveyors used a perch of ten Greek “Pous of Kyrenaika”, i.e. 3.087 m instead of the perch of ten of their own feet, equal 2.964 m.
According to this hypothesis – currently not supported by the majority of modern metrologists – all the Roman area measures should be multiplied by 625/576, i.e. 8.5 % larger.
If the irrefutable proof for the real existence of a Roman surveyor perch of 10 Roman feet 6⅔ digits can be adduced, then the saltus equates to one Roman square mile exactly.
According to this hypothesis – currently not supported by the majority of modern metrologists – all the Roman area measures should be multiplied by 625/576, i.e. 8.5 % larger.
If the irrefutable proof for the real existence of a Roman surveyor perch of 10 Roman feet 6⅔ digits can be adduced, then the saltus equates to one Roman square mile exactly.
