The compendium consists of a main box with a top cover. A projection on the cover latches onto the main box and there is also a swivelling suspension ring.
Around the sides of the box is the signature: 'HOC HOROLOGIVM FECIT VLRICVS SCHNIEP MONACENSIS AD ELEVATIONEM POLI 38 40 42 44 46 48 50 52 54 GRA ANNO [star] I.5.5.3.[star]'.
The top cover, with symmetrical foliate engraving in each corner of the plate, carries a combined nocturnal and volvelle (similar to that on Epact 35140). Orientation is indicated by 'MERIDIES' and 'SEPTENTRIO' placed in opposition outside a fixed zodiac scale. Each sign in the scale is divided to 10 and 2, and numbered by 10, and is indicated both by its name and (except for Capricorn) its symbol. The south point of the scale is approximately 8? Virgo.
The index pointer of the volvelle is marked A and its edge is cut away amongst the daylight hours to fully reveal the zodiac scale. The hours run 4 to 12 to 8 with small tooth projections, and their scale advertises the constellation with which the nocturnal was to be used: 'Horae noctis apud Vrsae maiorem inueniendae'. Presumably the guard stars of the Great Bear are intended. The rotating rule against which a star would be sighted is broken; its central disc is radially decorated.
The volvelle also provides the times of sunrise and sunset throughout the year for four latitudes. There are four concentric bands, each marked 'ORTVS SOLIS [star] HORA' and 'OCASVS SOLIS [star] HORA', for latitudes 42, 44, 46 and 48?. The times are read through apertures which reveal the fixed scale below, in which each hour is subdivided to 20 and 40 minutes. After setting the volvelle against the zodiac scale, the times are read off against the fiducial edges of the latitude scales.
The reverse of the cover carries a lunar volvelle and the two inner corners of the plate have foliate engraving. The plate is titled in a scroll 'CIRCVLI HORARV<M> LVNAE ET HORA: ITALICA:'. The fixed outer band gives the Latin names of the four principal directions and surrounds a series of mobile bands, which can no longer be rotated. There is a scale for Italian hours, 1 to 24, surrounding a scale of common hours I to XII, I to XII, which in turn surrounds a scale of common hours 1 to 12, 1to 12. A double aperture reveals a scale, presumably 0 to 291/2, for 'DIES ETATIS LVNAE'. There is also a circular aperture to reveal a diagram of the phases of the moon and an aspectarium stamped with the symbols for trine, quadrature, sextile and opposition.
The main box carries an inclining dial titled in scrollwork 'HOROLOGIVM SOLIS ET SIGNO ZODIACI', with a spring-loaded folding gnomon decorated with a central hole and trefoil engraving. The hours run 3 to 12 to 9 and surround lines indicating the sun's position in the zodiac throughout the year. The signs are indicated by their symbols and there are inscriptions for the 'TOPICVS [sic] CANCRI', 'AEQVINOCTIALIS' and 'TROP CAPRI:'. Cancer to Sagittarius is marked 'SIGNI DECRESCENTE DIE' and Capricorn to Gemini 'SIGNI CRESCENTE DIE'. A point cut out of the edge of the gnomon casts the shadow by which the sun's zodiacal position is read.
Fixed in the dial plate is the instrument's compass (diameter 21 mm). The silver base plate is engraved with a circle and a direction cross marked 'SE', 'OR', 'ME' and 'OC', along with an arrow indicating a westward variation of the compass.
The dial plate should pivot within the main box of the compendium, but the pivots are lost. When depressed at north, the dial plate reveals lines for latitudes 38, 40, 42, 44 and 46?. The compass bowl prevents a similar pressing down at south (perhaps a replacement?) but when the dial plate is removed, there are lines visible for 48, 50, 52 and 54?, as promised in the signature inscription.
The base has a two column table of the latitudes of 48 European places from 37 to 54?. Two holes are let into the plate under the compass bowl but there are no projections or fixtures to make use of them.