Ancient Roman units of measurement
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The ancient Roman units of measurement were built on the Greek system with Egyptian influences. The Roman units were generally accurate and well documented.
Contents |
[edit] Length
The Roman foot is defined to be 16⁄28 of the Nippur cubit.
| Roman unit | Latin name | Feet | Equivalence |
|---|---|---|---|
| one digit | digitus | 1⁄16 | 18.5 mm |
| one palm | palmus | 1⁄4 | 74 mm |
| one foot | pes | 1 | 296 mm |
| 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 stadion | stadium | 625 | 185 m |
| one mile | milliarium | 5000 | 1.48 km |
| one league | leuga | 7500 | 2.22 km |
Notes
- Since late Antiquity the Roman foot was sometimes divided into unciae, 12 equal parts.
Although, the ancient digit measure largely dominated before beginning of Middle Ages. - The value of the historical Roman foot scientifically obtained by modern statistical methods is 296.2 mm ± 0.5 mm (about 296.2 mm ±0.17%) (cf. Rottländer, Tübingen, Germany). The table above is based on this value, however 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, whilst descriptive is +0.27% out of the range given above.
[edit] Area
| Roman unit | Latin name | Acres | Equivalence |
|---|---|---|---|
| <center> pes quadratus | <center> 1⁄14 400 | <center> ~ 875 cm² | |
| <center> one square perch | <center> scripulum | <center> 1⁄144 | <center> ~ 8.75 m² |
| <center> one aune of furrows | <center> actus minimus | <center> 1⁄30 | <center> ~ 42 m² |
| <center> one rood | <center> clima | <center> 1⁄4 | <center> ~ 315 m² |
| <center>one acre | <center>actus quadratus also known as acnua | <center>1 | <center>~ 1260 m² |
| <center> one yoke | <center> iugerum | <center> 2 | <center> ~ 2520 m² |
| <center> one morn | <center> heredium | <center> 4 | <center> ~ 5040 m² |
| <center> one centurie | <center> centurium | <center> 400 | <center> ~ 50.4 ha |
| <center> one "quadruplex" | <center> saltus | <center> 1600 | <center> ~ 201.6 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.
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 |
|---|---|---|---|
| <center> one spoonful | <center> ligula | <center> 1⁄48 | <center> ~ 11⁄8 cl |
| <center> one dose | <center> cyathus | <center> 1⁄12 | <center> ~ 41⁄2 cl |
| <center> one sixth-sester | <center> sextans | <center> 1⁄6 | <center> ~ 9 cl |
| <center> one third-sester | <center> triens | <center> 1⁄3 | <center> ~ 18 cl |
| <center> one half-sester | <center> hemina | <center> 1⁄2 | <center> ~ 27 cl |
| <center> one double third-sester | <center> cheonix | <center> 2⁄3 | <center> ~ 36 cl |
| <center>one sester | <center>sextarius | <center>1 | <center>~ 54 cl |
| <center> one congius | <center> congius | <center> 6 | <center> ~ 31⁄4 l |
| <center> one urn | <center> urna | <center> 24 | <center> ~ 13 l |
| <center> one jar | <center> amphora | <center> 48 | <center> ~ 26 l |
| <center> one hose | <center> culleus | <center> 960 | <center> ~ 520 l |
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
| Roman unit | Latin name | Pecks | Equivalence |
|---|---|---|---|
| <center> one drawing-spoon | <center> acetabulum | <center> 1⁄128 | <center> ~ 63⁄4 cl |
| <center> one quarter-sester | <center> quartarius | <center> 1⁄64 | <center> ~ 131⁄2 cl |
| <center> one half-sester | <center> hemina | <center> 1⁄32 | <center> ~ 27 cl |
| <center> one sester | <center> sextarius | <center> 1⁄16 | <center> ~ 54 cl |
| <center> one gallon | <center> semodius | <center> 1⁄2 | <center> ~ 42⁄3 l |
| <center>one peck | <center>modius | <center>1 | <center>~ 82⁄3 l |
| <center> one bushel | <center> quadrantal | <center> 3 | <center> ~ 26 l |
Like the jar, the Roman bushel or "quadrantal" is one cubic foot. It is almost 26.027 L. One-third of a quandrantal is a Roman peck.
[edit] Weight
| <center> Roman unit | <center> Latin name | <center> Drachms | <center> Equivalence |
| <center> one chalcus | <center> chalcus | <center> 1 / 48 | <center> ~ 71 mg |
| <center> one siliqua | <center> siliqua | <center> 1 / 18 | <center> ~ 189⅓ mg |
| <center> one obolus | <center> obolus | <center> 1 / 6 | <center> ~ 0.568 g |
| <center> one scruple | <center> scrupulum | <center> 1 / 3 | <center> ~ 1.136 g |
| <center>one drachm | <center>drachma | <center>1 | <center>~ 3.408 g |
| <center> one shekel | <center> sicilicus | <center> 2 | <center> ~ 6.816 g |
| <center> one ounce | <center> uncia | <center> 8 | <center> ~ 27.264 g |
| <center> one pound | <center> libra | <center> 96 | <center> ~ 327.168 g |
| <center> one mine | <center> mina | <center> 128 | <center> ~ 436.224 g |
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 | |||
|---|---|---|---|
| <center> 1 ounce = | <center> uncia | <center> 7 ounces = | <center> septunx |
| <center> 2 ounces = | <center> sextans | <center> 8 ounces = | <center> bes |
| <center> 3 ounces = | <center> quadrans | <center> 9 ounces = | <center> dodrans |
| <center> 4 ounces = | <center> trians | <center> 10 ounces = | <center> dextans |
| <center> 5 ounces = | <center> quincunx | <center> 11 ounces = | <center> deunx |
| <center> 6 ounces = | <center> semis | <center> 12 ounces = | <center> as |
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 as in the Gregorian calendar an ordinary year is 365 days long and a leap year is 366 days long. The difference is which years are leap years. In the Julian calendar every fourth year is a leap year. The Gregorian calendar uses a more complex algorithm to more closely approximate the length of the tropical year.
[edit] References
Vormetrische Längeneinheiten by Rolf C. A. Rottländer, Rottenburg / Köln (also see Search-Engine).
Recovery of the Ancient System Foot/Cubit/Stadion — Length Units 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."
zfv (Zeitschrift für Geodäsie, Geoinformation und Landmanagment) 128. Jahrgang, Heft 3/2003, S. 211-217.
[edit] See also
- Systems of measurement
- History of measurement
- Units of measurementde:Alte Maße und Gewichte (Römische Antike)
eo:Romiaj mezurunuoj fr:Unités de mesure romaines it:Unità di misura romane la:Mensura Romana pl:Miary rzymskie
sl:Stare uteži in mere#Rimski sistem
