Noun
A form of balance in which the body to be weighed is suspended from the shorter arm of a lever, which turns on a fulcrum, and a counterpoise is caused to slide upon the longer arm to produce equilibrium, its place upon this arm (which is notched or graduated) indicating the weight; a Roman balance; -- very commonly used also in the plural form, steelyards.
Source: Webster's dictionaryHowever, some of Holbein's other portraits of Steelyard merchants, for example that of Derich Born, concentrate on the naturalness of the face. Source: Internet
The first reference to it as the Steelyard (der Stahlhof) occurs in 1422. Source: Internet
Wilson, 184. For the guildhall of the Steelyard Holbein painted two monumental allegories, "The Triumph of Wealth" and "The Triumph of Poverty", both now lost. Source: Internet