Portable horizontal dial for latitude 47° North. This is an octagonal silver dial with a gilt-brass gnomon and gnomon brace. On the obverse side is an hour scale with the numbers enamelled in black. The hour-lines radiate out from a small central decoration. The gnomon, which is shaped and pierced, folds flat when not in use. Around the compass is fine leaf decoration. The cardinal points are designated in Latin initials and North is offset by 10° West to allow for magnetic variation. The needle, with an arrowhead for North, is surmounted by a brass pyramidal pivot, and there is a chipped glass plate over all. The compass and one turned silver leg support the dial-plate. The reverse side is plain apart from a decorated gnomon brace. The case is of black morocco leather, octagonal shaped, with faded pink velvet lining and a push-button metal clasp.

The dial is signed 'Salomon Chesnon ABlois'. Chesnon is one of the few French instrument makers from outside Paris and Dieppe to be represented in this collection. Blois is a large town lying between Tours and Orleans in the Loire Valley. It has a latitude of 47° 35' and so this dial was probably designed for use locally. Similar dials were sold at Sotheby's, London in 1994, and at Christie's, South Kensington in 1997; another is in the Whipple Museum (accession no. Wh: 1224).

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