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Farey's ellipsograph, 1817.

Farey's ellipsograph dated 1817 in mahogany case. An ellipsograph is used to draw ellipses, which consist of a combination of two circular motions. The drawing pencil is fixed in position in a central ring, which then revolves. At the same time, the

 
The 'Brical' British calculator, 1905.

Brical' adding machine in case with two bone styluses. Patented by H and M Dickinson, the 'Brical' was Britain's answer to the French circular 'Tronset' instrument and is a modification of it. It was designed to add sums of money from 1/2d to £500.

 
GEM calculator, 1890.

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.

 
Bissaker's slide rule, 1654, and Thacher's calculating instrument, 1881.

The earliest known dated slide rule, made by Robert Bissaker, which uses scales bound together with metal bands.

 
Henrici's harmonic analyser, No 3, 1894.

Harmonic analyser designed by O.Henrici, made by G. Coradi, 1894. Harmonic analysers were designed to break down a complex wave, such as a sound wave, into its fundamental and harmonic components. This one uses the motions of three glass spheres whic

 
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

 
The 'Multiplicateur Enfantin' ready reckoner, c 1880.

Automatic calculator: Chambon's "Multiplicateur Enfantin". The device shows multiplication tables up to 50 times 28.

 
Gunnery callipers, French, 17th century.

Callipers, used for artillery purposes, French, 17th century. Callipers were used to measure the diameter of cannon balls and the bores of cannons. This example also containd scales for artillery calculations

 
Klein bottle, 1995.

A single surface model made by Alan Bennett in Bedford, 1995. It consists of three Klein bottles set inside each other sharing a common loop. When cut this gives a pair of single-twist Mobius strips. A Klein bottle has no edges, no outside or inside

 
Napier's rods, 1671-1700.

Napier's bones, cylindrical type, late 17th century. John Napier (1550-1617), discoverer of logarithms, created the popular calculating tool known as Napier's rods or bones. Napier's rods reduced muliplication to a sequence of simple additions; divis