LONDON.- Christie’s presents collectors with the opportunity to bid for an exceptionally rare Arithmetical machine. This ‘pocket-sized’ calculator, measuring 14.5 centimeters in width and 32.5 centimeters in length, is one of the earliest mechanical calculating devices known to exist and is the first portable device; only three other known examples of this design have survived. The French instrument by Parisian mechanician and watchmaker to His Royal Highness King Louis XIV – René Grillet de Roven dates from circa 1673 and will be offered in Christie’s bi-annual sale of Travel, Science and Natural History auction on Thursday, 10 October 2013. The exceptional piece is expected to realise between £70,000 and £100,000.

James Hyslop, Head of Travel, Science and Natural History, Christie's South Kensington commented, “This pocket-sized calculator is one of the earliest surviving pieces in the history of the computer. Mechanical calculators date from the 1640s, but were big clunky brass machines. This small lightweight machine, based on Napier’s logarithms was one of the earliest portable designs. I am proud to be presenting collectors with the opportunity to bid on such an exciting piece.”

The calculating device, contained in a complete walnut wooden box, comprises twenty-four rotating dials arranged in three rows of eight located on the interior lid. Each wheel consists of several concentric circles, while the bottom of the box contains a set of rolling cylinders carrying logarithmic tables. The Arithmetical machine performs all the arithmetic operations including addition, subtraction, multiplication and division through the use of these rolling rotating Napier’s bones.

Grillet exhibited his pocket sized machine during the 1670’s and 1680’s at markets and fairs throughout Paris and the Netherlands. The device is very rare to the market; with only three other known examples; two of these are in the Musée des Arts et Métiers, Paris and the other in the collections of IBM based in New York.