[CALCULATING DEVICE]. Cercle calculateur mobile.

… par V. Michaut Delacroix de Châtillon (Côte d’Or). Paris : Lith. de Paul Dupont et Cie., 1840. Printed card, 275 mm in diameter, wooden handle 290 mm in length, mounted in the centre to rotate; one side calculates rates of interest for wages, calculated at 6% from one day to 360 days; the other side calculates interest at the rate of 5% from one day to five years; considering its fragility, a remarkably well preserved example.

An extremely rare and early form of calculating device, with the printed date of 1840.

This is one of a number of mathematical and surveying instruments patented by Michaut-Delacroix (de la Croix), a surveyor from the regional town of Châtillon-sur-Seine, northwest of Dijon. His original application for a five-year patent on the Cercle calculateur mobile, dated 12 March 1840, can be viewed online at:

http://www.ami19.org/BrevetsFrancais/1840MichautDelacroix/1840MichautDelacroix.pdf

Above the imprint on the present example is printed Déposé à la Direction de la Librairie. Brevet d’Invention, indicating that the maker’s patent application was still under consideration by the relevant bureaucratic department at the time of publication.