Ring dial for latitude 53° North. This instrument consists of a fixed bracket, pierced by a suspension ring. On the outer face are two date scales, divided by month. The equinoxes are marked at approximately 22 March and 24 September and it is stamped 'LAT 53'. The inner face has two hour-scales with diagonal hour-lines across the dial. The summer scale is numbered IV-XII, I-VIII, and the winter scale VI-XII, I-VIII. There are ecliptic divisions parallel to the ring edges, indicated by months. A central sliding collar, which is moved by a buckle-type slider, carries two pinhole gnomons.

The use of IV rather than IIII on sundials is very rare, but IV does occur on some later instruments, particularly of the 19th century. The latitude stamped on the dial approximates to that of Sheffield (53° 23'). The dial is signed 'L. PROCTOR SHEFFIELD' on the outer face. Another ring dial by Proctor is in the Whipple Museum (accession no. Wh: 1179).

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