around a Greek racing stadium. It was equal to 625 Roman
feet, ⅛ of a Roman mile.
Romans measured weight in a unit called a libra, which
was divided into 12 base units of equal weight, also called
unciae. A libra weighed 11.5 ounces, just short of a modern
pound. Accordingly, each uncia weighed just a bit less than an
ounce. Another term for libra was as. Asses or librae were not
just units of measurement for weighing commercial goods;
they were also used to establish the value of Roman currency,
emphasizing just how critical a standard of weights and mea-
sures was to the Roman economic system.
Liquid volume was measured in a unit called an am-
phora. Borrowed f rom Greece, t his unit was equiva lent to 6.8
gallons of liquid. In the ancient Mediterranean terra-cotta
vessels called amphorae were used to transport liquids like
oil and wine. Th e volume of the amphora is equivalent to
1 cubic foot of liquid and is thought to be derived from the
amount of liquid a human being can comfortably carry. Th e
Romans also employed smaller volume units. For example, 1
amphora was equal to 8 congii, each of which had a volume
of 0.85 gallons. One congius contained 12 heminae, each
of which had a volume of 0.57 pints. A sextarius consisted
of 2 heminae. For measuring either dry or liquid volume,
the Romans used the modius (pl. modii). Th is volume was
equivalent to 2.4 gallons of liquid. Th e modius was further
subdivided into 16 units for liquid measure called sextarii;
each had a volume of 1.1 pints.
Romans used four main units to measure land area. Th ey
were used in land division and distribution for colonial, agri-
cultural, and military endeavors. Th e basis for these calcula-tions was the actus, a unit of length equal to 120 feet. A square
actus, actus quadratus, was equivalent to 14,400 square Ro-
man feet, or about ⅓ acre. Next was the jugerum, possibly
derived from the average area two oxen could plow in a single
day. One jugerum equaled 2 actus quadrati. Two jugera made
a heredium, which measured approximately 1.25 acres. Th e
largest denomination of land area was the centuria, which
was equivalent to 100 heredia, approximately 125 acres dur-
ing the republic but up to 200 heredia in the empire. Th e ori-
gin of the centuria was the approximate area occupied by an
encamped century of the Roman military.
Th e Roman system of weights and measures was partially
standardized during the late republic. Although there were
slight regional variations in units, the basic units of distance,
length, weight, volume, and area were uniform throughout
republican and imperial territory. Elected offi cials called ae-
diles were responsible for regulating the system of weights of
measures in towns and cities throughout Roman territory. In
Rome the standards for weights and measures were kept at
the Roman Forum in the Temple of Castor and Pollux. Em-
ploying a uniform system of weights and measures, Rome was
able to div ide its la nd, mint money, a nd excha nge commercia l
goods over a vast territory while using a common vocabulary
from Britain to the Persian Gulf.THE AMERICAS
BY KIRK H. BEETZ
Exactly what the weights and measures were for ancient
Americans is among the mysteries of ancient American
life. For most ancient cultures archaeologists rely heavily on
written records for identifying weights and measures, and
most ancient Americans left no such records. Some ancient
American cultures did have written languages, but it seems
that they did not deem their weights and measures worthy
of recording. For instance, merchant transactions among
the ancient Maya were written on the ground, in dirt, with
stones, seeds, or other small objects serving to mark num-
bers, presumably including those that stood for weight, vol-
ume, and length; the transactions were then memorized and
the dirt and markers reused for other transactions. A lack of
physical evidence adds to the mystery. For instance, in other
parts of the world metal scales for weighing objects have
been found and their uses identifi ed, but Americans made
little use of metal in the ancient era. Th ey may have used
wooden measuring devices or devices that combined wood,
bone, and stone. If both the wood and the bone decayed, ar-
chaeologists would have only the stones, and the stones may
look like nothing special.
Researchers expect weights and measures to appear in
cultures that trade extensively among themselves and with
outsiders and that have a central government which can im-
pose standards for weights and measures on people. Th is as-
sumption would seem to leave the cultures of the Innuits and
the people of the plains of North America out of the picture.Roman cup or bowl depicting a man carving the number 7 on a
nilometer, a device used to measure the water level of the Nile’s annual
fl ood (© Th e Trustees of the British Museum)weights and measures: The Americas 11810895-1194_Soc&Culturev4(s-z).i1181 1181 10/10/07 2:31:22 PM