File:Post Medieval sun dial; pocket ring dial. (FindID 424905).jpg

English: Post Medieval complete cast copper-alloy 'pocket' sundial of 17th or 18th century date. The sundial is of the simple ring type. It consists of a broad, flat, copper alloy ring with a channel (sometimes corroded to a void) cut in the centre of the outer side along its circumference which originally would have been filled with a separate sliding collar. This is now missing.

The exterior has two four incised lines running around it, one near each edge and two flanking the channel. The channel breaks through to the interior of the ring to create a slot along two-fifths of the circumference. This slot is flanked on the outer side by horizontal incised gradation lines running from the slit to the inner incised lines and the initials of the months of the year, in groups of six arranged to either side: 'I F M A M I' to one side (for the first months of the year) and 'I A S O N D' (for the later months of the year) to the other side.

The interior has three incised lines running around it, one towards each edge and one in the centre. These circumferential lines on the interior are interrupted by the central slot. Around two fifth of the diameter the central line is marked by 12 indented dots. Each dot is flanked by two stamped digits representing the hours of the day: 8, 7, 6, 5, 4, 3, 2, 1 above and: 4 5 6 7 8 910 11 12 below the central line and dots. The surface of the ring dial has not developed a patina, most likely or has been over cleaned, which the finders tend not to do, therefore it is has an abraded red copper coloured surface. The ring dial measures 34.59mm diameter; width: 32.22mm; thickness: 10.06mm. Weight: 8.6g.

These sundials are known as simple ring dials or poke dials ('poke' being an archaic word for pocket). The sliding collar would be set into position for the month of the year and, when the dial was suspended vertically, the sun would shine through the hole in the lozenge shaped piece, through the slot, and onto the interior of the ring. The time could then be read by looking at the closest gradation mark to the spot of light on the interior of the ring. Turner states "A cheap dial, it was popular during the seventeenth and eighteenth centuries among country people who kept it in their poke, or pocket. Not infrequently they are literally unearthed (Turner, G L'E, 1980. <a href="../../../database/publications/publication/id/2195" title="View reference work's details">Antique Scientific Instruments</a> Poole, Dorset : Blandford Press Ltd, pp 25).