Ready reckoner for ship's cargoes

Ready reckoner or calculating scale, boxwood weighted with brass, for gross and tare weights of ship's cargoes, engraved "Robert Ludgate, Custom House, London, 1807"

Ready reckoners made calculations faster and simpler. This example aided the calculation of the weight of a ship’s cargo, and might have helped a customs officer ensure the correct fees and charges were levied on shipping merchants.

Tare is the weight of the packaging or container. The instrument’s tables and scales enable a user to find the gross (overall) weight based on the tare weight, which could be set at 7lbs, or at a percentage of the weight of the goods.

Robert Ludgate was one of a number of instrument-makers located close to London’s Custom House. When this ready-reckoner was made, London was Britain’s busiest port, and a hub of national and international trade. Taxes on imported and manufactured goods were an important source of government revenue. By the 1700s the bureaucracy for collecting and administering them was substantial.