FRANCE, vers 1825-1835 ITROPE (?) Jeune, Engineer Optician, in Chartres. Thermometer terminal in centigrade and Réaumur, in the shape of pedestal out of brown-black patinated brass, decorated with frieze of leaves and crowned trompe and of a crown of laurel. Signed "Itropé Jne Ing. Opten in Charters" on the silver plate. Base in yellow marble of Siena. H. 22 cm. Scratches on the plate; base restored, chips. Provenance : Auguste VERNEUIL (1856-1913), inventor of synthetic ruby.