One of the faces has a folding triangular gnomon indicating common hours from 10 to 12 to 8, and with a decorative sun effigy and strapwork inscribed 'HOR{AE} EQVAL{IS}'. This gnomon has two other tips which serve as gnomons for the lower dial, inscribed 'QVANTITAS DIEI' from 8 to 16 and 'QVANTITAS NOCTI' from 16 to 8, and unequal hours indicated XII and VI to VIIII. The tropics and equinoctial lines are also inscribed 'TROPI:<CUS> CAPRICO{RNI}', 'TROPICVS CANCRI' and 'AEQVINOCTIALIS'.

The second face of the dial probably had another triangular gnomon, now missing, to indicate common hours from 4 to 12, then 1 and 2, inscribed in strapwork 'HORA{E} EQVALES' with a sun effigy. Below this dial, similar to the previous side, is another dial inscribed 'QVANTITAS DIEI' from 8 to 15, and 'QVANTITAS NOCTI' from 16 to 8. Unequal hours are engraved XII and then III to VI, and the tropics and equinoctial lines are also engraved 'TROP:<ICVS> CAPRIC:<ORNI>', 'TROPICVS CANCRI' and 'AEQVATOR DIEI'.

The third face of the dial is inscribed with a table of ruling planets, 'TABVLA GVBERNANTIVM PLANETARVM DIEI IN HORIS INAEQVALIBUS', with headings for the unequal hours and the corresponding ruling planet for each day of the week.

The fourth face of the dial is engraved with a figure of justice, represented as a woman holding a six-point star and inscribed 'IVSTICIA', with strapwork on the upper part. This is an unusual representation. On the border is the signature 'HOC OPVS VECIT VDVLRICVS SCHNIEP DE MONACO [star] ANNO DOMINI MDLXVII ELEVA POLI 48'.

On the top of the column is a hinged lid with engraved dome and finial, and within is a compass.

Inside the instrument is an ingenious levelling device consisting of a slotted brass plumb-bob with lead weight below the slot, and at its top a silvered disc engraved with a rosette. The upper edge of the slot rests in a V- shaped knife-edge attached to a vertical bar, this latter assembly fitting tightly within the case. Levelling is obtained by centralising the disc within the open top.

The instrument was purchased in 1890 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. 31, no.63.