A black marble Napoleon III mercury regulator mantle clock, circa 1870s, with maker's stamp of Vincent et Cie, the elegant architectural arched clock with a visible escapement and a black chapter ring with Roman numerals, the glazed section below housing the mercury pendulum, upon an extended base, with refined and striking inlaid malachite adornments, with key and in working order, height 51.5 cm, width 37 cm, depth 21 cm