Automatic calculator: Chambon's "Multiplicateur Enfantin". The device shows multiplication tables up to 50 times 28.
Replica of a quipu made from an original held at the Museum of Natural History, New York, in 1974. Quipus were used by the Incas during the 15th and early 16th centuries as records of all types of accounts. It was discovered in the early 20th 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
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.
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
Model to show face-centre cubic packing made of ping-pong balls.1975. This model imitates a stuctural form found in crystals.
A single surface model made by Alan Bennett in Bedford, 1995. It consists of a parallel sided coil with loops piercing the return tube which when theoretically cut gives a pair of 13-twist Mobius strips. A Klein bottle has no edges, no outside or ins
Single surface glass vessel made by Alan Bennett in Bedford, 1995 The triple loop Klein bottle when cut gives a pair of five-twist Mobius strips. A Klein bottle is a surface which has no edges, no outside or inside and cannot properly be constructe
Wire model of a 'cylindroid' by Howard Grubb, Dublin in brass glazed cylindrical case on a wooden base. The model was made on the instructions of Robert Stawell Ball who wrote the definitive work 'A treatise on the Theory of Screws' in 1900. Thomas G
Playskool wooden toy, a wooden framework with rotating blocks bearing numbers and symbols to do arithmetic. 1960-1980. Toys to help with arithmetic were introduced from the start of the 20th century.