The instrument is in the form of a box with a friction-clasped lid. The outer faces are purely decorative: the outer face of the lid has an engraving of Mercury between two columns; the sides have foliage engraving; and the base carries strapwork and foliage.
The inner face of the cover carries a horizontal pin-gnomon dial marked for Italian hours XI to XXII. Lines numbered from 8 to 16 for 'QVANTITAS DIEI' and 16 to 8 for 'QVANTITAS NOCTI' indicate the length of the day or night between the 'TROPICVS CANCRI' and 'TROPICVS CAPRICORNI'. The pin is placed within a sun and the signature '[star] VS [star]' and date 1570 are placed above a cartouche with the inscription 'HORA ITALICE ET QVANTITA: DIEI DIEI [sic] ET NO'.
The main box contains a horizontal string-gnomon dial with a decorated folding gnomon support sprung to the vertical and incorporating a plummet. The silvered dial plate is numbered 5 to 12 to 7 and also has half hour lines. At the southern end is the latitude for which the instrument was to be used '[star] POLVS 46 GRAD ' and another signature '[star] VS [star]'. The inset compass is 20 mm in diameter; its bowl has a cross of direction labelled 'S', 'OR', 'M' and 'OC' and is marked for variation.
Provenance: Lewis Evans Collection G. 381.