## On Display

A 2 foot boxwood slide rule for navigators, c.1800. 'Sliding Gunters' , or navigator's rules with a slide are comparatively rare, as most navigators preferred to stick with the ordinary 'Gunter' scale based on the combination of trigonometric, logari

A single surface model made by Alan Bennett in Bedford, 1995. It consists of a sphere with three interlinked loops the equivalent of three interconnected Klein bottles. A Klein bottle has no edges, no outside or inside and cannot be properly construc

Mechanical counting device, c 1900. Devices for counting the revolutions or repetitive actions of machines were developed from the mid 19th century.

Set of 'arithmetical scales' by Smith and Dolier, late 19th century. These 'scales' were used to set many different sums in addition and subtraction. Pupils in a class would probably have used slates to do the sums.

Calculating Rule 'Parker's Prestometer Tablet', c.1860 by Isaac Aston, London. One side of the rule is inscribed with multiplication tables involving halves.the other side has more complicated scales involving areas and volumes.

A single surface model made by Alan Bennett in Bedford, 1995. It consists of a Klein bottle cut to form one single-twist Mobius strip. A Klein bottle is a surface which has no edges, no outside or inside and cannot be properly constructed in three d

A single surface model made by Alan Bennett in Bedford, 1995. It consists of a Klein bottle cut to form one single-twist Mobius strip. A Klein bottle is a surface which has no edges, no outside or inside and cannot be properly constructed in three di

A single surface model made by Alan Bennett in Bedford, 1995. It consists of a Klein bottle cut to form one four-twist band. A Klein bottle is a surface which has no edges, no outside or inside and cannot be properly constructed in three dimensions.

Single surface models made by Alan Bennett in Bedford, 1995. Four small Klein bottles (left to right): i) one loop relating to the single-twist Mobius strip, ii) two loop relating to the three-twist Mobius strip, iii) three loops relating to the five

Set of Napier's bones in boxwood, in a boxwood case. John Napier (1550-1617), discoverer of logarithms, also created this popular calculating tool known as Napier's cylindrical 'rods' or 'bones'. Napier's bones reduced muliplication to a sequence of