The inner side of the upper leaf has a table for converting unequal hours, engraved from 1 to 12 twice, and common hours, engraved on the outer circle from 1 to 12 twice, divided to the quarter hour by alternate shading. Day and night hours are named 'DIEIS' and 'NOCTIS', and the twilight line is dotted and inscribed 'ORIENS' and 'OCCIDENS'. A previous incorrect engraving reads 'DIEIS' underneath 'NOCTIS'. The spandrel spaces are decorated with foliage. Fixed at the centre is an eccentric zodiac band, divided by 30?, subdivided by 10 and by 5, numbered from 10 to 30 by 10. The zodiacal symbols are engraved on the inner part of the band. On top of the zodiac band is a brass arm, with a star burst in the centre and geometric decoration.

In the main box is a universal equinoctial dial, with hour lines engraved on a silver circle from I to XII twice, divided to the half hour by alternate shading, the circle fixed on a brass circular support. On the brass ring are engraved five latitudes 42, 45, 48, 52 and 54. The other side of the silver ring is engraved with common hours, divided to the half hour by alternate shading, and numbered from 1 to 12 twice. The base of the brass support, near the hinge, is decorated with scrollwork.

Inside the main box is a silver plate with a compass well in the middle, and hours engraved around it from I to XII twice. A small circular well probably contained an enamel decoration. The spandrel spaces are decorated with foliate scrolls.

The back of the silver circular plate is engraved with cities and latitudes in four rings, from the external one: 'INCOLSTAT 48', 'NORENPERG 49', 'VENEDIG 45', 'LISIBONA 39', 'DRESSEN 51', 'MAILANT 45', 'BARSOLONA 39', 'WITENBERG 52'. The second ring has 'FRANCKFORT 50', 'AVGSPVRG 48', 'SALTZBVRG [?]', 'ERFORT 51', 'PARIS 48', 'HERTZBVRG 52', 'FREIBVRG [?]', 'FLORENTZ 43'. The third ring has 'STRAVBING 48', 'PASS[?]R 48', 'ANDORF 5 [?]', 'BREMEN 54', 'TRENT 45', 'NEAPOLIS 42', 'STVCKART [?]', 'MINGEN 48'. The fourth ring has 'BERLIN 53', 'WIEN 48', 'BRESLAV 51', 'COLN 51', 'SPEIR 49', 'LOVEN 51', 'ROMA 42', 'PRAG 50'. The silver ring is fixed with two screws and nuts, one of which is missing.

The inside of the lower leaf is engraved with a table of ruling planets for each month and for each day of the week, headed 'HORA PLANETARVM DIEIS' and 'HORA PLANETARVM NOCTIS'. The days of the week are named 'SONDAG', 'MENDAG', 'ERICHDAG', 'MITWOCH', 'PFINSDAG', 'FREYDAG', 'SAMSDAG'.

The outside face of the lower leaf is engraved in the manner of a quadrant. A degree scale is engraved on the limb, divided by ten and by five, subdivided by one by alternate shading, numbered by five. Common hour lines are engraved on the right hand side, from 4 to 12 to 8, and on the left hand side is a vertical zodiac scale, with each sign divided to ten and five degrees, numbered from 10 to 30 by 10. The symbols of the zodiacal signs are engraved on the sides, and the signs are named in German, from top to bottom: 'STEINPOCK', 'WASSERMAN', 'FISCH', 'WIDER', 'STYER', 'ZWILLING', 'SCHVTZ', 'SCHORPIO', 'WAG', 'IVNGFRA', 'LEO', 'KREWS'. Next to the apex is a shadow square divided to one and numbered from 4 to 12 by four, with a human figure with a spade and a severed head on the other hand. A small hole on the apex was meant to hold the plumb bob which is now missing. The space opposite the apex is decorated with a landscape and men using astronomical instruments.

On one side of the main box are two hole sights.

The instrument was bequeathed in 1888 by Octavius Morgan, and is described in F. A. B. Ward, A Catalogue of European Scientific Instruments in the Department of Medieval and Later Antiquities of the British Museum (London, 1981), p.121, no.351.