Planimeter by Beuvière, unsigned, France, circa 1845, in its wooden case L. 54cm. Missing the graduated glass ruler.
Instrument for measuring area, designed by A. Beuvière, former Chief Surveyor of the Cadastre and professor at the Conservatoire des arts et métiers. Two examples, slightly different, are in the CNAM museum. See Catalogue of the Museum: section A, Instruments and calculating machines, 1942, 129. For its operation see H. de Morin, Les appareils d'intégration ..., 1913, 73-5.