Pair of kitchen scales and weights, made in Sweden, c 1880.

Pair of kitchen scales and weights, made in Sweden, c 1880.

Money-changer's balance, 1653.

Calculating scale, 1807.

Calculating scale, 1807.

Slide rule, 1815. Made by W Cary. Slide rul

Slide rule, 1815. Made by W Cary. Slide rul

Chinese scales, 19th century.

Hayward's slide rule, 19th century. Made by

Equal arm postal balance, 1850-1880.

Balance with scale pans, c 1370-1350 BC.

Weideman's stilliard, 1750-1800.