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
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.
Addiator' decimal adding machine with stylus and pencil on metal stand. Made by the Addiator-Gesellshaft Company of Berlin, Germany, the 'Addiator' was a relatively late mechanical calculator. It uses a chain mechanism, a stylus to add or subtract an
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
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.
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
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, 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 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
"Tachylemme" of C.L.Chambon, c.1876. This instrument shows the daily interest on sums of money at various rates.