A rare double dial inlaid rosewood mystery timepiece, D.Desmet Heltzel, French, circa 1850

two 6-inch adjacent glass dials with gilt numerals and single hands inscribed Minutes and Heures and within heavy gilt bezels concealing the toothed edge of the revolving glass panels, the gilt brass shaped support engraved Première pendule à mouvement invisible avec aiguille des minutes faites par D.Desmet Heltzel à Brugea, the drive  provided by an adapted French clock movement with silk suspension, the going train driving the hours hand and the former strike train driving the minutes hand, the movement concealed within a bow-ended rosewood marquetry plinth inlaid  with  boxwood flowers, leaf scrolls and stringing; with a glass dome