Nice English Roberval letter scale with one weight and one letter plate. A set of four staple weights are insert in the beautiful inlayed marble base. 

Classic design made by many firms from 1840 to around 1940. Many variations in decorative style including, filigree brass bases, china bases, Wedgwood plaques set into the plates, enameled patterns, inlaid stone flowers, etc, etc. The plain style shown is the most common. Weights were commonly flat, round, stacking, and provident with a knob on the top one ( often missing ). Top two weights normally the same value, e.g. 1/4, 1/4 oz or 1/2, 1/2 oz. Weights over 2 oz were often lead cased in brass. " Bottle " weights or square knobbed weights were also used.