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Automatic calculator: Chambon's "Multiplicateur Enfantin". The device shows multiplication tables up to 50 times 28.
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
Set of 7 assembled cardboard geometrical models on wooden stands showing the surfaces of the second order.
Gem' calculating machine, J.Guthrie's patent No 15062, 1890. The GEM calculator is a simple device for the addition of English money. Numbers are added by inserting a stylus against the figure and pulling downward.
Planimeter (rolling type) by G. Coradi, Zurich, in case, 1886. Planimeters were used by engineers and scientists to measure the area inside a closed curve.
Gunners callipers, 6 inch by H.Gregory, brass 18th century. These callipers ere used for measuring the diameter of cannon balls, or by crossing the arms, the bore of a cannon..
Carpenter's 2-foot folding rule in boxwood with logarithmic slide, made by James Rabone & Sons, Birmingham, mid to late 19th century. This is a standard carpenter's rule of the period and includes scales for calculating the volume of wood and the p
Gunner's callipers by Thomas Wright, early 18th century. The callipers can be used as shown to measure the diameter of cannon balls, or with crossed arms to measure the bore of a cannon. The arms are inscribed with tables containing information relat
"Tachylemme" of C.L.Chambon, c.1876. This instrument shows the daily interest on sums of money at various rates.
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
