A single surface glass vessel made by Alan Bennett in Bedford, United Kingdom. It consists of three Klein bottles sharing an inlet tube which when cut produces three pairs of single-twist Mobius strips. A Klein bottle is a surface which has no edges,
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.
Twist & Shout Multiplication' a digital and audio mathematical toy by Leap Frog, a division of Knowledge Kids Enterprises. Complete with packaging, instructions and marked as manufactured in China, c.2000. This toy employs all the latest technology
Laundry tally board, English, of wood, brass and horn
`Baby Calculator' stylus adding device by Glenview, Illinois, USA, c. 1960. Like the Exactus, this is one of a number of simple stylus machines introduced in the mid 20th century. It performs multiplication and division by repeated addition and subtr
Mechanical ready reckoner patented by Patented by James Hines. This form of calculator gave costs of various quantities of goods at various prices per pound, hundredweight or ton. The quantity was set by turning the apropriate wheel at the side, and
A single surface glass vessel made by Alan Bennett in Bedford, 1995. Its form is a variation on the Klein bottle with an inlet passing through the vessel which when cut forms a pair of single-twist Mobius strips. A Klein bottle is a surface which has
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