Ancient Roman units of measurement
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The ancient Roman units of measurement were built on the Hellenic system with Egyptian, Hebrew, and Mesopotamian influences. The Roman units were comparatively consistent and well documented.
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[edit] 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[1] |
| one cubit | cubitus | 11⁄2 | 444 mm |
| one step | gradus | 21⁄2 | 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. That is, 36 Roman feet to 35 English feet, making the Roman foot slightly shorter than its modern equivalent. 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 or approximately 11.65 English inches. 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 (297 mm). This comparison, although descriptive, is +0.27% out of the range given above.
[edit] Area
| Roman unit | Latin name | Acres | Equivalence |
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also known as acnua |
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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.
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.
[edit] Volume
[edit] Liquid measures
| Roman unit | Latin name | Sesters | Equivalence |
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The Roman jar, so-called "amphora quadrantal" is the cubic foot. The congius is half-a-foot cubed. The Roman sester is the sixth of a congius.
[edit] Dry measures
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| Roman unit | Latin name | Pecks | Equivalence |
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Like the jar, the Roman bushel or "quadrantal" is one cubic foot. It is almost 26.027 litres. One-third of a quandrantal is a Roman peck.
[edit] Mass and coins
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The Roman pound is exactly three quarters of the Greek mine.
Thus the Greek and Roman drachm is related by the ratio 32 to 25.
| All the multiples of the Roman ounce have their own names | |||
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One and a half ounces was called by Romans "sescuncia". Some of these nouns were used to designate Roman bronze coins.
[edit] Time
The Julian calendar was introduced in 45 BC replacing the earlier Roman calendar. In the Julian calendar, an ordinary year is 365 days long, a leap year is 366 days long, and every fourth year is a leap year. The Gregorian calendar differs from the Julian calendar in that it skips three leap years every four centuries to more closely approximate the length of the tropical year.
[edit] References
- ^ Accuracy of length units Google translation of http://vormetrische-laengeneinheiten.de/html/genauigkeit.html by Rolf C. A. Rottländer, Rottenburg / Köln
[edit] Sources
- Vormetrische Längeneinheiten by Rolf C. A. Rottländer, Rottenburg / Köln (also see Search-Engine).
- Recovery of the Ancient System Foot/Cubit/Stadion by Dieter Lelgemann, acting 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.
- Knobloch, Eberhard, Dieter Lelgemann und 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.
- Reference draws of the Nippur Cubit at Florencetime.net.
- Proposal to Add Ancient Roman Weights and Monetary Signs to UCS (Universal Character Set)
