Silver and Enamel Centre Seconds Calendar Verge

A late 18^th Century Swiss centre seconds verge with day date calendar in a silver and enamel open face case.  Full plate gilt fusee movement.  Finely pierced and engraved bridge cock with steel coqueret, plain three arm gilt balance with blue steel spiral hairspring.  Silver regulator dial with blue steel indicator.  Polished steel mainspring setup ratchet and click.  Wound through the white enamel dial, subsidiary chapter of Arabic numerals at six o'clock for time, two further subsidiaries above for date and day in French.  Sweep centre seconds hand, fine gold hands. Silver open face case with ribbed middle.  Polychrome enamel scene on the back of a couple resting by a lake.  The sky and background in translucent enamel over an engine turned ground.  Translucent turquoise enamel border over an engine turned ground.