Twelve replica German jetons, originals date from the 16th century. These small counters were placed on a counting cloth in a similar manner to beads on an abacus.
An early example of the Comptometer, with 72 numbered keys. The top of box has a plate engraved with varoius patents up to 1891. The Felt and Tarrant Comptometer was one of the first generation of mass-produced office calculators. It was extremely su
Brass sector (Gunter's pattern) by Elias Allen 1623. Allen made the sector to the design of Edmund Gunter who published a description of it in the same year. Sectors were used from the end of the 16th century until the mid 19th for calculations invol
Gunner's quadrant and perpendicular by George Adams the Younger, c.1780. This instrument was designed primarily to ensure that a cannon or mortar was elevated to the required angle. Quadrants were also used for navigational purposes to determine the
Japanese soroban or abacus with 13 columns, each with 5 beads below the bar and one above.This represents an intermediate form between the original Chinese abacus and the modern Japanese type. This arrangement was common from the late 19th century u
Stylus-operated Indian currency adder, wooden backboard with handmade varnished card face inscribed 'R.G.W. 24.2.12'. The GEM calculator was originally patented in 1890 as a simple device for the addition of English money. Numbers are added by insert
McFarlane calculating cylinder, c1835. This is a ready reckoner inscribed with tables giving various percentages of various sums of money in sterling.
'Tachypoly Plasiasme' ready reckoner, 1880-1884. Invented by C L Chambon in 1880, the 'Tachypoly plasiasme' ready reckoner showed multiplication tables up to 100 times 100.
Set of 7 assembled cardboard geometrical models on wooden stands showing the surfaces of the second order.
A single surface model made in glass by Alan Bennett in Bedford, 1995. It consists of a Klein bottle with three loops, one of which has been cut away and sectioned to form a pair of single twist Mobius strips. A Klein bottle is a surface which has n