GERMANY. Mainz. Erzbistum. Friedrich Karl Joseph von Erthal, 1774-1802. Dukat 1795 (Gold, 22 mm, 3.47 g, 12 h), Mainz FS JA (die engraver J. F. Stieler and mint master J. Aatz). FRID•CAR•IOS•A EP•ET EL•MOG•EP•W• Draped bust of Friedrich Karl Joseph von Erthal to right, F•S• below. Rev. AVREA MOGVNTIA City view, MDCCLXXXXV / I•A• below. Friedberg 1685. Pick 791. Walther 655. Tiny marks and copper spots, otherwise, extremely fine.

The picturesque reverse of this ducat depicts the pontoon bridge of Mainz, which crossed the Rhine between 1661 and 1885, linking Mainz with Kastel. The roadway, extending for roughly 500 meters, rested on a chain of 48 wooden barges. To allow ships to pass, two movable spans could be opened as required. In 1844, the wooden barges were replaced by iron pontoons, while the laborious manual opening of the movable sections was superseded by steam-powered machinery. During periods of flooding or heavy ice drift, the entire bridge had to be withdrawn to a protected harbor for safety