A fine gilt and silvered brass diptych dial, probably German,...

A fine gilt and silvered brass diptych dial, probably German, dated 1643,
signed with initials S.A.V.Z. Ano.1643, the unusual construction with extended box on the upper outer face housing a plumb bob and with finely fretted covers to allow sight of the compass below, upper inner face with vertical string gnomon dial with central fret work engraved with a fantastical face, silvered brass horizontal string gnomon dial with inset compass well, the lower outer face with tables showing day and night lengths against calendar scales, raised on four ornate bun feet, the sides of the dial are applied with scrolling silver frets held in place with screws, when open,
3 1/3in x 3in x 2in (8 1/2cm x 8cm x 5cm)
Provenance:
Private European collection.
Trevor Philip & Sons, Ltd., 2003.
Private collection.