Astrolabe, 1558

Technical characteristics

Date

1558

Type

Flemish astrolabe

Maker

Jacobus Valerius (attributed)

Material

Brass

Geography

Flemish

Dimensions

133 mm in diameter

Place recorded

Flemish (attributed)

Missing components

Latitude plates and rete

Maker / attribution

Jacobus Valerius (attributed)

Design

Visible features

• The limb is engraved with a degree scale 0 to 360 and a scale of hours numbered I to XII twice. • The central space on the back contains a projection of the celestial sphere. • The interior surface of the mater is densely engraved with a radiating table of numbers for astronomical calculations. • The limb is fixed to the back plate, shackle, and suspension ring.

Attribution and Origin

The instrument is attributed to the maker Jacobus Valerius, based on stylistic parallels to an existing instrument in Brussels bearing his name. There is scholarly uncertainty regarding the place of manufacture; while the table of numbers specifically addresses the needs of Zaragosa, Spain, political ties between the Spanish crown and the Netherlands suggest that a Flemish origin is plausible. The complexity of the calculations suggests the astrolabe was intended for a user with specific scholarly or specialist requirements. The absence of the rete and latitude plates limits its current utility, yet the existing engraving provides clear evidence of its original design and function.

Construction and Mater

The astrolabe is constructed of brass and measures 133 mm in diameter. Currently, only the mater remains, with the limb soldered directly to the back plate. The suspension mechanism, including the shackle and ring, is extant. The interior surface of the mater is entirely occupied by a radiating table of numbers used to determine conjunctions, oppositions, and solar and lunar eclipses. This table is specifically calculated for the Spanish town of Zaragosa, referred to in the instrument as Caesar Augusta, and covers the years 1558 to 1570. The limb is engraved with a degree scale of 0 to 360 and a scale of hours numbered I to XII twice. The outer rim is marked with the names of the 12 classical winds.

The Reverse and Scales

The reverse of the astrolabe is decorated with 13 concentric scales. The outermost scale represents 90 to 0 to 90 degrees, followed by a zodiacal scale including names and symbols for each 30-degree section. A circle indicates the positions and magnitudes of certain stars, while additional circles contain planetary symbols and a calendar scale with Latin month names. The central area of the back features a projection of the celestial sphere in the lower half. One of the upper quadrants contains a shadow square labeled 'VMBRA VERSA' and 'VMBRA RECTA', with scales 0 to 12. The opposing quadrant holds an unequal hour diagram and solar altitude lines every 5 degrees, marked with the inscription 'RECTIFICATA ? ANNO ? XPI ? 1558'.

Identification

Inventory Number

48892

Source note

Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.

Catalogue references

No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.