Roman Steelyard Balance 1st-3rd Century AD
A steelyard (statera) balance consisting of a rectangular beam with disc-shaped terminals, three hanging chains ending in a large hooks, and suspended lead contra weight on iron hook . The face of the beam is sectioned using incised Roman numerals to mark the weight; around 150 grams, length of the bar 185mm. Steelyard balances were used to weight loads by moving a counterweight along the beam until it balanced and then reading the incised numeral. Vitruvius describes them and their function in his De Architecture, Book X, 3-4. See this slightly larger example with a weight that sold at Christie's for approximately $7852 in 2008: http://www.christies.com/lotfinder/Lot/a-late-roman-bronze-steelyard-balance-and-5060684-details.aspx