Imitation ring dial for latitude 48° North. The ring is made of brass and has a fixed suspension bracket through which a leather thong is threaded. On the outer face is a date scale and an inscription: 'IO.H.S.THON ANNO 1721.' The equinoxes are marked at approximately 19 March and 19 September. On the inner face is an hour scale and an inscription: 'PIZ BUIN'. There is a central sliding collar, containing a pinhole, which can be moved by means of a small projecting piece. The ring comes with accompanying promotional information, in German, giving instructions on its use: 'hold the dial by the thong, so that the Sun shines through the hole in the central ring. The point of light that appears on the inside shows you the time.'

Metallwarenfabrik manufactured 150,000 of these dials as a promotion for 'Piz Buin', and they were sold worldwide. The accompanying literature also explains their relationship with the original dial (made by Johannes Thon in 1721). Unfortunately, many of the dials have been sold on without the information about their origins and are now often bought by unsuspecting collectors as genuine 18th century instruments.

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