Roman Weights

• Roman Weights were measured on Roman Scales.
• The base Roman unit of Weight was the Uncia, the modern ounce (oz), and 12 Unciae made 1 Libra, the modern pound (lb).

The Units

• Uncia:
  • The base unit (one modern ounce or 28 grams)
• As:
  • This was 6 Uncia.
• Libra:
  • This was 12 Uncia. Libra abbreviates to the modern pound (lb) and weighed 3/4 lb.

Roman Scales

• The Roman Scale was an instrument used for weighing which consisted of two types of balance.
• One was a lever, suspended in the centre, to two arms of equal length, with the scales hanging from each end.
• The other was also a suspended lever but with arms of unequal length. The item to be weighed was attached to the smaller arm and the weight was then moved out along the notched arm until it balanced.