On Display

Chuckrum board, Indian, late 19th century.

Chuckrum board with 108 small coins.This board was used to count 100 small 'chuckrum' coins rapidly by spreading them over the surface to fill the holes.

Kelvin's harmonic analyser, 1878.

Kelvin's harmonic analyser, 1878. The machine was Invented by William Thomson, Lord Kelvin, (1824-1907), a pioneering Irish physicist. The harmonic analyser was designed to analyse graphical records of daily changes in atmospheric temperature and pre

Arithmetical Jewel, 1619.

The 'Arithmetical Jewel' publicised by William Pratt in 1619. This instrument combines features of an abacus with those of pen reckoning. Numbers are put in by moving the flags to reveal dots. Sums are then worked out with a pen and paper.

Exchequer tally and foil, English, 1822.

An exchequer tally dated 1822. The English Exchequer used tallies to record deposits from the mid-12th century until 1826. Notches show the amount paid; differently spaced notches standing for a penny, a shilling, £1, £20, £100 and £1000.

Boxwood Coggeshall folding slide rule, 1720-1730.

Boxwood Coggeshall rule, folding with slide, c. 1720-1730. Until the early 19th century slide rules were usually made for specific trades. This is a type of carpenter's rule.

Klein bottle, 1995.

A single surface model made by Alan Bennett in Bedford, 1995. It consists of a Klein bottle with coiled inlet tube, or jacketed coil with singularity and entrance at opposite ends, which when theoretically cut gives a pair of 19-twist Mobius strips.

Timetable or rent rule, 1850-1860.

Timetable or rent rule for calculating the number of weeks for storage charges, as used by the dock companies, by Dring and Fage, Tooley Street, London, c. 1850-1860. The rule allows the number of weeks to be read off between two dates up to two yea

Two gilt bronze arithmetical medals, 1753.

Two gilt bronze "arithmetical medals" sold by J.Maddux at the "Hand and Pen", Brook Street, Holbourn, c. 1753. The medals are inscribed with the multiplication tables up to 10 on one side and the 12 times table on the other. They indicate the relativ

Circular slide rule, 1660-1680.

A circular slide rule, made by John Brown, with two brass radial arms and an stronomical quadrant engraved on the back. A spiral slide rule affords a long and therefore accurate logarithmic line in a small amount of space. The potential of spiral rul

Chinese abacus or Suan Pan, 19th century.

Chinese abacus, or suan-pan, 19th century