A quinaria (plural: quinariae) is a
Roman unit of
area
Area is the measure of a region's size on a surface. The area of a plane region or ''plane area'' refers to the area of a shape or planar lamina, while '' surface area'' refers to the area of an open surface or the boundary of a three-di ...
, roughly equal to
.
Its primary use was to measure the cross-sectional area of pipes in Roman water distribution systems. A "one quinaria" pipe is in diameter.
In Roman times, there was considerable ambiguity regarding the origin of the name, and the actual value of a quinaria. According to
Frontinus
Sextus Julius Frontinus (c. 40 – 103 AD) was a Roman civil engineer, author, soldier and senator of the late 1st century AD. He was a successful general under Domitian, commanding forces in Roman Britain, and on the Rhine and Danube frontier ...
:
...Those who refer (the quinaria) to Vitruvius and the plumbers, declare that it was so named from the fact that a flat sheet of lead 5 digits wide, made up into a round pipe, forms this ajutage. But this is indefinite, because the plate, when made up into a round shape, will be extended on the exterior surface and contracted on the interior surface. The most probable explanation is that the quinaria received its name from having a diameter of 5/4 of a digit...
In other words,
Vitruvius
Vitruvius ( ; ; –70 BC – after ) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work titled . As the only treatise on architecture to survive from antiquity, it has been regarded since the Renaissan ...
claimed that the name was derived from a pipe created from a flat sheet of lead "5
digits wide", roughly , but Frontinus contested the definitiveness of this because the exterior circumference of the resulting pipe would be larger than the interior circumference. According to Frontinus, the name and value is derived from a pipe having a diameter of "5/4 of a digit". Using Vitruvius' standard, the value of a quinaria is , and the resulting pipe would have a diameter of .
The importance of this measure was that water taxes in ancient Rome were based on the size of the supply pipe.
[Robert Graves]
See also
*
Ancient Roman weights and measures
The units of measurement of ancient Rome were generally consistent and well documented.
Length
The basic unit of Roman linear measurement was the ''pes'' (plural: ''pedes'') or Roman foot. Investigation of its relation to the English foot goes ...
*
Water theft#Roman period
Notes and references
External links
''The Quinaria'', part of the Encyclopædia Romana
Units of area
Human-based units of measurement
Ancient Roman units of measurement
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