Diptych dial for latitude 49° North. Miniature rectangular ivory diptych dial consisting of two leaves that fold flat when the dial is not in use. Leaf Ia is bare. Leaf Ib features a vertical dial for use with a string gnomon, which is missing. There are various stellar motifs in red. Leaf IIa has a compass with the meridian line offset at 5° East of North. On it is Jacob Karner's makers mark - '3'. The needle is blued, has an arrowhead for North and is surmounted by a brass pyramidal pivot. A glass plate covers all. Below this is a dial for Italian hours, with a brass pin gnomon, with the hour-lines and numbers in black. Various stellar motifs decorate the leaf. Leaf IIb is bare apart from Karner's makers mark in the centre towards the top. The leaves have a silver hook fastener and a silver hook for holding the dial open.

Miniature diptych dials were a common variant of the Nuremberg makers' craft, particularly during the 18th century (see AST0291, AST0289, AST0254 and AST0414). The number 3 that Jacob Karner used as his maker's mark may reflect the fact that he was a third-generation diptych maker.

For more information regarding this dial please refer to the OUP & NMM catalogue, 'Sundials at Greenwich'.