Astronomical compendium for unknown latitude. This is a round, gilt-brass compendium with a suspension ring attached to the hinge. The lid carries a nocturnal with a date scale and a zodiac scale. The equinoxes are marked at approximately March 10 and September 8. It has a rotatable brass disc with teeth and a pointer, on which is an hour scale. Stars are engraved on the rest of the surface. It has a rotatable index arm with a hinged end, inscribed 'VRSA MAIOR' (Great Bear). Inside the lid is a printed and painted compass card. It has a green and white wind-ring and an eight point compass rose in red, gold and white. The base has a lunar volvelle consisting of fixed scales and a rotatable disc. The fixed disc has an hour scale and a lunar-age scale and the rotatable disc has an hour scale with a rectangular hole cut out to reveal the lunar-age scale. This has a ring of stars, a central sunface and a circular aperture to allow the viewing of a pictorial representation of the phases of the moon.

Although the compass card in the base of the compendium is clearly Italian, the style of the instrument suggests that it was made in Germany and that the compass card was a later addition. Nothing apart from the compass card remains inside. The instrument may have included either a horizontal dial or a universal equinoctial dial.

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