On Display

    Klein bottles, 1995.

    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

     
    Napier's Bones, c 1690.

    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

     
    Brunsviga calculating machine, 1892.

    Brunsviga calculating machine with lid, no262. c.1892. This barrel calculating machine represents the Brunsviga in its earliest form. Barrel calculating machines were smaller, lighter and easier to operate than Arithmometers. The machine performs mu

     
    Exactus stylus-operated adding and subtracting device, 1955-1965.

    Exactus stylus-operated adding and subtracting device, with swivelling half plate for add and subtract options, marked "Mini-Add Made in England", c. 1950. The Exactus is one of several simple stylus-operated calculators to have been popular in the

     
    French sector, 1751-1774.

    Brass French sector by Canivet, Paris, 1751-1774. French sectors are less complicated than English sectors. They are also used for calculations involving proportions of length, area and volume.The lines radiate from the centre of the hinge.

     
    Klein bottle, 1995.

    A single surface model made by Alan Bennett in Bedford, 1995. It consists of a parallel sided coil with one piercing of the return tube which when theoretically cut gives a pair of 15-twist Mobius strips. A Klein bottle has no edges, no outside or in

     
    A stchoty, Russian abacus, early 20th century.

    Stchoty (Russian form of Abacus), early 20th century. The stchety has horizontal rows of beads rather than vertical as in the Japanese abacus. It is specifically for counting rubles and kopeks. The lower three rows are for the kopeks. The rest positi

     
    Robertson's 'Rapid Calculator', c 1910.

    Robertson's Rapid calculator, pat no. 5871,1910. Made by the Robertson Rapid Calculator Company of Glasgow, this was one of several large-scale ready reckoners to be developed in the first decade of the 20th century. This form of ready reckoner place

     
    Set of Napier's rods, 1770-1790.

    Set of Napier's bones, in wooden case with trade label of "J. Imison, Clock & Watch Maker, Optician, &c., No. 58 Hay-market, London", late 18th century. Napier's bones were invented in 1617 by Lord Napier of Murchiston, the inventor of logarithms, as

     
    The 'Tachylemme' ready reckoner, c 1876.

    "Tachylemme" of C.L.Chambon, c.1876. This instrument shows the daily interest on sums of money at various rates.