Ancient Roman units of measurement: Difference between revisions
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|style="padding:0 8px;"| modius |
|style="padding:0 8px;"| modius |
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|style="padding:0 8px; text-align:right;"| 16 sextarii |
|style="padding:0 8px; text-align:right;"| 16 sextarii |
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|style="padding:0 8px; text-align:right;"| 8.73 l |
|style="padding:0 8px; text-align:right;"| 8.73 l (or 8.62 l) |
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|style="padding:0 8px;"| modius castrensis |
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|style="padding:0 8px; text-align:right;"| 24 sextarii |
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|style="padding:0 8px; text-align:right;"| (12.93 l?)<ref>Dominic Rathbone, "Earnings and Costs: Living Standards and the Roman Economy (First to Third Centuries AD), p. 301, in Alan Bowman and Andrew Wilson, ''Quantifying the Roman Economy: Methods and Problems''.</ref> |
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|colspan=3 style="font-size:smaller;"| Except where noted, based on Smith (1851).<ref name="smith" /><br />Metric equivalents are approximate. |
|colspan=3 style="font-size:smaller;"| Except where noted, based on Smith (1851).<ref name="smith" /><br />Metric equivalents are approximate. |
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Revision as of 21:27, 15 September 2014
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The ancient Roman units of measurement were built on the Hellenic system with Egyptian, Hebrew, and Mesopotamian influences.[citation needed] The Roman units were comparatively consistent and well documented.
Length
The basic unit of Roman linear measurement was the pes or Roman foot. Investigation of its relation to the English foot goes back at least to 1647, when John Greaves published his Discourse on the Romane foot. Greaves visited Rome in 1639, and measured, among other things, the foot measure on the tomb of Titus Statilius Aper, that on the statue of Cossutius formerly in the gardens of Angelo Colocci, the congius of Vespasian previously measured by Villalpandus, a number of brass measuring-rods found in the ruins of Rome, the paving-stones of the Pantheon and many other ancient Roman buildings, and the distance between the milestones on the Appian Way. He concluded that the Cossutian foot was the "true" Roman foot, and reported these values compared to the iron standard of the English foot in the Guildhall in London:[1]
| Source | Reported value in English feet | Metric equivalent |
|---|---|---|
| Foot on the statue of Cossutius | 0.967 | 294.7 mm |
| Foot on the monument of Statilius | 0.972 | 296.3 mm |
| Foot of Villalpandus, derived from Congius of Vespasian | 0.986 | 300.5 mm |
| Metric equivalents are approximate. | ||
Smith (1851) gives a value of 0.9708 English feet, or about 295.9 mm.[2] An accepted modern value is 296 mm.[3]
The Roman foot was sub-divided either like the Greek pous into 16 digiti or fingers; or into 12 unciae or inches. Frontinus writes in the 1st century AD that the digitus was used in Campania and most parts of Italy.[4] The principal Roman units of length were:
| Roman unit | English name | Equal to | English equivalent | Metric equivalent | Description |
|---|---|---|---|---|---|
| digitus | finger | 1⁄16 pes | 0.0607 ft (0.728 in) | 18.5 mm | |
| uncia or pollex | inch or thumb | 1⁄12 pes | 0.0809 ft (0.971 in) | 24.6 mm | |
| palmus | palm width | 1⁄4 pes | 0.243 ft | 74 mm | |
| palmus major | palm length | 3⁄4 pes | 0.728 ft | 222 mm | in late times |
| pes | foot | 1 pes | 0.971 ft | 296 mm | |
| palmipes | 11⁄4 pedes | 1.214 ft | 370 mm | ||
| cubitus | cubit | 11⁄2 pedes | 1.456 ft | 444 mm | |
| gradus or pes sestertius | step | 21⁄2 pedes | 2.427 ft | 0.74 m | |
| passus | (double) pace | 5 pedes | 4.854 ft | 1.48 m | |
| decempeda or pertica | perch | 10 pedes | 9.708 ft | 2.96 m | |
| actus (in length) | 120 pedes | 116.496 ft | 35.5 m | ||
| stadium | furlong | 625 pedes | 607.14 ft | 185 m | |
| mille passuum or milliarium[5][6][7] | mile | 5000 pedes | 4854 ft (0.919 standard mi) | 1.48 km | |
| Gallic leuga | league | 7500 pedes | 7281 ft (1.379 standard mi) | 2.22 km | |
| Except where noted, based on Smith (1851).[2] English and Metric equivalents are approximate, converted at 1 pes = 0.9708 English feet and 296 mm respectively. | |||||
Area
The ordinary units of measurement of area were:
| Roman unit | English name | Equal to | Metric equivalent | Description |
|---|---|---|---|---|
| pes quadratus | square foot | 1 pes² | 0.0876 m² | |
| scrupulum or decempeda quadrata | 100 pedes² | 8.76 m² | the square of the standard 10-foot measuring rod | |
| actus simplex | 480 pedes² | 42.1 m² | 4 × 120 pedes[8] | |
| uncia | 2400 pedes² | 210 m² | ||
| clima | 3600 pedes² | 315 m² | 60 × 60 pedes[8] | |
| actus quadratus or acnua | 14400 pedes² | 1262 m² | also called arpennis in Gaul[8] | |
| jugerum | 28800 pedes² | 2523 m² | ||
| heredium | 2 jugera | 5047 m² | ||
| centuria | 200 jugera | 50.5 ha | formerly 100 jugera[8] | |
| saltus | 800 jugera | 201.9 ha | ||
| Except where noted, based on Smith (1851).[2] Metric equivalents are approximate, converted at 1 pes = 296 mm. | ||||
Other units of area described by Columella in his De Re Rustica include the porca of 180 × 30 Roman feet (about 473 m²) used in Hispania Baetica and the Gallic candetum or cadetum of 100 feet in the city or 150 in the country. Columella also gives uncial divisions of the jugerum, tabulated by the anonymous translator of the 1745 Millar edition as follows:
| Roman unit | Roman square feet | Fraction of jugerum | Metric equivalent | Description |
|---|---|---|---|---|
| dimidium scrupulum | 50 | 1⁄576 | 4.38 m² | |
| scrupulum | 100 | 1⁄288 | 8.76 m² | |
| duo scrupula | 200 | 1⁄144 | 17.5 m² | |
| sextula | 400 | 1⁄72 | 35.0 m² | |
| sicilicus | 600 | 1⁄48 | 52.6 m² | |
| semiuncia | 1200 | 1⁄24 | 105 m² | |
| uncia | 2400 | 1⁄12 | 210 m² | |
| sextans | 4800 | 1⁄6 | 421 m² | |
| quadrans | 7200 | 1⁄4 | 631 m² | |
| triens | 9600 | 1⁄3 | 841 m² | |
| quincunx | 12000 | 5⁄12 | 1051 m² | |
| semis | 14400 | 1⁄2 | 1262 m² | = actus quadratus[2] |
| septunx | 16800 | 7⁄12 | 1472 m² | |
| bes | 19200 | 2⁄3 | 1682 m² | |
| dodrans | 21600 | 3⁄4 | 1893 m² | |
| dextans | 24000 | 5⁄6 | 2103 m² | |
| deunx | 26400 | 11⁄12 | 2313 m² | |
| jugerum | 28800 | 1 | 2523 m² | |
| Except where noted, based on Millar (1745).[8] Metric equivalents are approximate, converted at 1 pes = 296 mm. | ||||
Volume
Both liquid and dry measures were based on the sextarius. As no two surviving examples are identical, scholarly opinion ranges from 0.53 l[9] to 0.58 l.[10] Cardarelli gives a value 0.54928 l.[11] A 1952 estimate for its value in Pliny the Elder's Natural History estimated it as 500 ml.[12]
Since the Romans themselves defined the sextarius as 1/48th of an amphora quadrantal, and the amphora quadrantal as one cubic foot, assuming a value of 296 mm for the Roman foot yields a theoretical value for the sextarius of about 540.3 ml, which falls comfortably within the accepted range.
The core volume units are:
- amphora quadrantal (Roman jar) – one cubic pes (Roman foot)
- congius – a half-pes cube (thus 1⁄8 amphora quadrantal)
- sextarius – literally 1⁄6, of a congius
Liquid measures
| Roman unit | Equal to | Metric |
|---|---|---|
| ligula | 1⁄48 sextarius | 11.4 ml |
| cyathus | 1⁄12 sextarius | 45 ml |
| acetabulum | 1⁄8 sextarius | 68 ml |
| quartarius | 1⁄4 sextarius | 136 ml |
| hemina or cotyla | 1⁄2 sextarius | 273 ml |
| sextarius | 1⁄6 congius | 546 ml |
| congius | 6 sextarii | 3.27 l |
| urna | 4 congii | 13.1 l |
| amphora quadrantal | 8 congii | 26.2 l |
| culeus | 160 congii | 524 l |
| Except where noted, based on Smith (1851).[2] Metric equivalents are approximate. | ||
Dry measures
| Roman unit | Equal to | Metric |
|---|---|---|
| ligula | 1⁄48 sextarius | 11.4 ml |
| cyathus | 1⁄12 sextarius | 45 ml |
| acetabulum | 1⁄8 sextarius | 68 ml |
| quartarius | 1⁄4 sextarius | 136 ml |
| hemina or cotyla | 1⁄2 sextarius | 273 ml |
| sextarius | 1⁄6 congius | 546 ml |
| semimodius | 8 sextarii | 4.36 l |
| modius | 16 sextarii | 8.73 l (or 8.62 l) |
| modius castrensis | 24 sextarii | (12.93 l?)[13] |
| Except where noted, based on Smith (1851).[2] Metric equivalents are approximate. | ||
Weight
The units of weight (in the everyday sense of the word; technically, "mass") were mostly based on factors of 12. Several of the unit names were also the names of coins during the Roman Republic and had the same fractional value of a larger base unit: libra for weight and as for coin. Modern estimates of the libra range from 322 to 329 grams (11.4 to 11.6 oz) with 5076 grains or 328.9 grams (11.60 oz) an accepted figure.[3][10][14]
The uncial divisions of the as or libra were:
| Roman unit | English name | Equal to | Metric equivalent | Description |
|---|---|---|---|---|
| uncia | Roman ounce | 1⁄12 libra | 27.4 g | |
| sescuncia or sescunx | 1⁄8 libra | 41.1 g | ||
| sextans | 1⁄6 libra | 54.8 g | ||
| quadrans or teruncius | 1⁄4 libra | 82.2 g | ||
| triens | 1⁄3 libra | 109.6 g | ||
| quincunx | 5⁄12 libra | 137.0 g | ||
| semis or semissis | 1⁄2 libra | 164.5 g | ||
| septunx | 7⁄12 libra | 191.9 g | ||
| bes or bessis | 2⁄3 libra | 219.3 g | ||
| dodrans | 3⁄4 libra | 246.7 g | ||
| dextans | 5⁄6 libra | 274.1 g | ||
| deunx | 11⁄12 libra | 301.5 g | ||
| as or libra | Roman pound | 328.9 g | ||
| Except where noted, based on Smith (1851).[2] Metric equivalents are approximate, converted at 1 libra = 328.9 g . | ||||
The subdivisions of the uncia were:
| Roman unit | English name | Equal to | Metric equivalent | Description |
|---|---|---|---|---|
| siliqua | 1⁄144 uncia | 0.19 g | ||
| obolus | 1⁄48 uncia | 0.57 g | ||
| scrupulum | 1⁄24 uncia | 1.14 g | ||
| semisextula | 1⁄12 uncia | 2.28 g | ||
| sextula | 1⁄6 uncia | 4.57 g | ||
| sicilicius | 1⁄4 uncia | 6.85 g | ||
| duella | 1⁄3 uncia | 9.14 g | ||
| semuncia | 1⁄2 uncia | 13.7 g | ||
| uncia | Roman ounce | 27.4 g | ||
| Except where noted, based on Smith (1851).[2] Metric equivalents are approximate, converted at 1 libra = 328.9 g . | ||||
Time
 |
Years
The complicated Roman calendar was replaced by the Julian calendar in 45 BC. In the Julian calendar, an ordinary year is 365 days long, and a leap year is 366 days long. Between 45 BC and 1 AD, leap years occurred at irregular intervals. Starting in the year 4 AD, leap years occurred regularly every four years. Year numbers were rarely used; rather, the year was specified by naming the Roman consuls for that year. When a year number was required, the Greek Olympiads were used, or the count of years since the founding of Rome, "ab urbe condita" in 753 BC. In the middle ages, the year numbering was changed to the Anno Domini count.
The calendar used in most of the modern world, 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.
Weeks
The Romans grouped days into an eight-day cycle called a nundina, with every eighth day being a market day.
Independent of the nundinae, astrologers kept a seven-day cycle called a hebdomada where each day corresponded to one of the seven classical planets, with the first day of the week being Saturn-day, followed by Sun-day, Moon-day, Mars-day, Mercury-day, Jove-day, and lastly Venus-day. Each astrological day was reckoned to begin at sunrise. The Jews also used a seven-day week, which began Saturday evening. The seventh day of the week they called Sabbath; the other days they numbered rather than named, except for Friday, which could be called either the Parasceve or the sixth day. Each Jewish day was reckoned to begin at sunset. Christians followed the Jewish seven-day week, except that they commonly called the first day of the week the Dominica, or the Lord's day. In 321 Constantine the Great gave his subjects every Sunday off in honor of his family's tutelary deity, the Unconquered Sun, thus cementing the seven-day week into Roman civil society.
Hours
The Romans divided the daytime into twelve horae or hours starting in the morning and ending in the evening. The night was divided into four watches. The duration of these hours varied with seasons; in the winter, when the daylight period was shorter, its 12 hours were correspondingly shorter and its four watches were correspondingly longer.
Astrologers divided the solar day into 24 equal hours, and these astrological hours became the basis for medieval clocks and our modern 24 hour mean solar day.
Although the division of hours into minutes and seconds did not occur until the middle ages, ancient astrologers had a minuta equal to a 60th of a day (24 modern minutes), and a secunda equal to one 3600th of a day (24 modern seconds).
Unicode
Ancient Roman units of measurement were added to the Unicode Standard in April, 2008 with the release of version 5.1.
The Unicode block for ancient Roman units of measurement, called Ancient Symbols, is U+10190–U+101CF:
| Ancient Symbols[1][2] Official Unicode Consortium code chart (PDF) | ||||||||||||||||
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
| U+1019x | 𐆐 | 𐆑 | 𐆒 | 𐆓 | 𐆔 | 𐆕 | 𐆖 | 𐆗 | 𐆘 | 𐆙 | 𐆚 | 𐆛 | 𐆜 | |||
| U+101Ax | 𐆠 | |||||||||||||||
| U+101Bx | ||||||||||||||||
| U+101Cx | ||||||||||||||||
| Notes | ||||||||||||||||
See also
References
- ^ Greaves, John (1647) A discourse of the Romane foot and denarius; from whence, as from two principles, the measures and weights used by the ancients may be deduced London: William Lee
- ^ a b c d e f g h Smith, Sir William; Charles Anthon (1851) A new classical dictionary of Greek and Roman biography, mythology, and geography partly based upon the Dictionary of Greek and Roman biography and mythology New York: Harper & Bros. Tables, pp. 1024–30
- ^ a b Hosch, William L. (ed.) (2010) The Britannica Guide to Numbers and Measurement New York, NY: Britannica Educational Publications, 1st edition. ISBN 978-1-61530-108-9, p.206
- ^ Sextus Julius Frontinus (c. 100 AD) De aquis 1:24. English translation.
- ^ Kamm, Antony (2008). The Romans: an introduction. Routledge. p. 144. ISBN 978-1-134-04799-4. Retrieved 10 December 2011.
- ^ Mattingly, David (2008). An Imperial Possession: Britain in the Roman Empire, 54 BC – AD 409. Penguin. p. 146. ISBN 978-0-14-014822-0. Retrieved 10 December 2011.
- ^ Goldsworthy, Adrian (2008). Caesar: Life of a Colossus. Yale University Press. p. 210. ISBN 978-0-300-12689-1. Retrieved 10 December 2011.
- ^ a b c d e Lucius Junius Moderatus Columella, Anon. (trans.) (1745) L. Junius Moderatus Columella of Husbandry, in Twelve Books: and his book, concerning Trees. Translated into English, with illustrations from Pliny, Cato, Varro, Palladius and other ancient and modern authors London: A. Millar. pp xiv, 600. Pages 208–216.
- ^ Inc NetLibrary, inc Encyclopædia Britannica (2009). Encyclopædia Britannica almanac 2008. Encyclopædia Britannica. p. 162. ISBN 978-1-59339-475-2. Retrieved December 2011.
{{cite book}}: Check date values in:|accessdate=(help) - ^ a b Zupko, Ronald Edward (1977). British weights & measures: a history from antiquity to the seventeenth century. University of Wisconsin Press. p. 7. Retrieved 9 December 2011.
- ^ Cardarelli, François; M.J. Shields (tr.) (2003). Encyclopaedia of Scientific Units, Weights and Measures: Their SI Equivalences and Origins. Springer. pp. 74–5. ISBN 9781852336820.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ W.H. Jones (1954). "Pliny's Natural History (Introduction to Chapter 6)".
- ^ Dominic Rathbone, "Earnings and Costs: Living Standards and the Roman Economy (First to Third Centuries AD), p. 301, in Alan Bowman and Andrew Wilson, Quantifying the Roman Economy: Methods and Problems.
- ^ Skinner, Frederick George (1967). Weights and measures: their ancient origins and their development in Great Britain up to A.D. 1855. H.M.S.O. p. 65. Retrieved 9 December 2011.
External links