Augsburg dial by Johann Martin made for latitudes 2° to 90° North. A compass, with the magnetic variation marked at 8° West of North, is set into the silver dial-plate, which is supported by three feet. The latitude arc is gilt-brass and the hour ring is silver. Attached to the hour ring is a gilt-brass gnomon. A plumb bob support is hinged to the South side of the dial-plate.

The back of the compass is engraved with a Rojas projection. Three small volvelles are positioned round the compass base representing a lunar calendar, a perpetual calendar and a dial for Italian and Babylonian hours. There is a separate disc with a nocturnal on the obverse side and a windrose on the reverse. Various places are inscribed radially to show their longitude East of the Canary Islands (often used as the prime meridian at this time).

This beautiful dial by Johann Martin is considerably more intricate than the standard Augsburg dial. A gilt-brass wind vane for use with the windrose is also included among the set of instruments. On the obverse side of the dial-plate, it is signed 'Johann Martin a Augsbourg 18'. The dial has an octagonal shaped case on whose lid is engraved a table of latitudes. A very similar instrument was in the Greppin collection and sold in 1975. The King George III collection in the Science museum also contains a similar dial (inventory no. 1927-1467).

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