La Multi, prototype of French calculating device based on Napier's bones, seven figures, c. 1920. This is a prototype of an instrument which did not prove successful. Napier's bones, a calculating device invented by John Napier in 1617, allowed the u
Rectangular protractor in brass, engraved "Dollond, London", late 18th century.As well as the usual angular scale the instrument contains a diagonal scale for plotting distances on a map or plan.
The Sinclair Executive Electronic Pocket Calculator (cutaway for exhibition) was the first electronic pocket calculator that could really fit into a pocket. Clive Sinclair (b. 1940) was able to achieve this by reducing the power input demanded by the
Electronic Pocket Calculator by Isot, model Elka 101, c1976. Before the fall of the Iron Curtain in 1989, Bulgaria hasd one of the largest electronics industries in Eastern Europe. However in the 1970s they had to import the integrated circuits to co
Surveyor's sector, Italian, early 17th century, engraved "Adam Heroldt fecit Romae". The sector was invented independantly by Galileo and Thomas Hook at the end of the 16th century. It primarily measures proportions and can contain lines concerning t
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
Little Professor' calculator, children's working educational toy / game, 1980. Electronic calculators were now low cost available items which could be targetted at children and those with straightforward requirements. This example was exhibited in th
Harding's improved counter by Harding, Richardson, Rhodes and Co. Ltd., Leeds. Revolution counters were devised to keep a record of the operation of machinery.
Numeric Demonstrator', an elementary teaching aid patented by Ethel Linay in about 1900.. This elementary arithmetical teaching apparatus consists of ten wooden rods with squared paper pasted on them in order to show multiplication visually.
S & N adding machine by Seidel & Naumann, Dresden, serial no. 2398, in fitted box with stylus and instructions. The Seidel and Naumann adding machines used chain drives and a stylus. The numbers to be added were pulled down to the base bar and then a