Portable auctioneer's equal-arm balance

100 oz "Auctioneers' Plate Valuing" sensitive brass balance and weights by De Grave and Co., 1901-2, for silver specie, in fitted mahogany case 22"x11 1/2"x5" deep. (Also used in valuations for probate etc. Listed by De Grave Short and Co. Ltd, London, in catalogue of 1900

Portable equal-arm balance mounted on a mahogany carrying case containing a set of brass cup and grain weights. Made by De Grave & Co. Ltd., London, these scales were designed for use by auctioneers who needed to weigh precious metals accurately to give valuations. Equal-arm balances of this type are the simplest and earliest method of weighing. They consist of a beam that has a pan suspended at either end. In use objects to be weighed are placed in one pan while weights of known mass are placed in the other pan until the two are balanced with the bar level. The product of these weights gives the mass of the commodity being measured.