Cadran Calculateur Claudel.

Remiremont : Mougin, 1887. Narrow octavo (240 x 120 mm), publisher’s blind-blocked red percaline over boards with metal corners and clasp, containing the calculator itself, printed on folding thick board 230 x 230 mm, with wooden ruler still attached by the original screw; preceded by a [4]-page summary and with a printed sheet of formulae pasted on the inside of lower board; [together with] the accompanying “user manual”, octavo (230 x 150 mm), publisher’s cloth-backed printed card covers (darkened and chipped), pp. 34, internally good.

Extremely rare calculating device invented and patented by Claudel in 1885. The calculator is accompanied by its explanatory booklet and is complete with its boxwood ruler allowing instant reading of various operations: multiplications, divisions, fractions, proportions, square roots, cubic roots, logarithms, surfaces and volumes, speed, and vapour pressures; there are also various other applications for engineers, architects or builders.

No example traced in libraries worldwide. (An example in the IBM collection is incomplete, and lacks the explanatory booklet).