weights and measures: The Americas Roman cup or bowl depicting a man carving the number on a nilometer, a device used to measure the water level of the Nile’s annual flood (© The Trustees of the British Museum) 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 measures was to the Roman economic system Liquid volume was measured in a unit called an amphora Borrowed from Greece, this unit was equivalent to 6.8 gallons of liquid In the ancient Mediterranean terra-cotta vessels called amphorae were used to transport liquids like oil and wine The volume of the amphora is equivalent to cubic foot of liquid and is thought to be derived from the amount of liquid a human being can comfortably carry The Romans also employed smaller volume units For example, amphora was equal to 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 heminae For measuring either dry or liquid volume, the Romans used the modius (pl modii) This volume was equivalent to 2.4 gallons of liquid The 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 They were used in land division and distribution for colonial, agricultural, and military endeavors The basis for these calcula- 1181 tions was the actus, a unit of length equal to 120 feet A square actus, actus quadratus, was equivalent to 14,400 square Roman 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 actus quadrati Two jugera made a heredium, which measured approximately 1.25 acres The largest denomination of land area was the centuria, which was equivalent to 100 heredia, approximately 125 acres during the republic but up to 200 heredia in the empire The origin of the centuria was the approximate area occupied by an encamped century of the Roman military The 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 officials called aediles 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 Employing a uniform system of weights and measures, Rome was able to divide its land, mint money, and exchange commercial 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 numbers, presumably including those that stood for weight, volume, 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 identified, but Americans made little use of metal in the ancient era They may have used wooden measuring devices or devices that combined wood, bone, and stone If both the wood and the bone decayed, archaeologists 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 impose standards for weights and measures on people This assumption would seem to leave the cultures of the Innuits and the people of the plains of North America out of the picture