Brass Astrolabe, 16th century (?)
Record status
Individual type · partial
Period
16th century (?)
This 16th-century (?) brass planispheric astrolabe (inventory 37527) is of North African origin. It features a compass-bearing throne with an integrated base, a simple round-section ring, and an eye-bolt shackle.
The mater and limb are constructed of two pieces, soldered and riveted together, with a degree scale on the limb. The instrument includes eight latitude plates, an alidade, and a rete of the simple indicator-line type with trefoil-based star pointers and four silver rotational knobs. The back of the instrument is engraved with seven distinct scales, including altitude, zodiacal signs, calendar, unequal hours, sine/cosine, and a shadow square.
Acquired by the University of Oxford in 1952, the instrument was previously held in the collection of John Selden, who bequeathed it to the Bodleian Library in 1659.
Evidence at a glance
- Linked sources
- 1
- Photograph views
- 1
- Catalogue references
- 0
Counts describe this entry’s documentation, not authenticity, rarity or completeness. Photographs may show one specimen; check each caption and licence.
Technical characteristics
- Date
- 16th century (?)
- Type
- Arabic-inscribed astrolabe, North Africa
- Material
- Brass
- Rete Type
- Indicator-line
- Provenance
- John Selden collection
- Throne Type
- Compass bearing
- Place recorded
- North Africa
- Place of Origin
- North Africa
Design
- Visible features
- • Rete features trefoil-shaped bases for star pointers • Four silver rotational knobs on the rete • Double-ended alidade with rigid, simple, single-pinhale sights • Teardrop-shaped guide near the suspension ring
- Back Scales and Layout
- The back of the astrolabe is engraved with seven distinct scales used for astronomical and timekeeping calculations. These include circular, concentric scales for altitude, zodiacal signs, and the calendar, which are arranged in the outer circular areas. The zodiacal signs are labeled in Arabic script. Additional functions include unequal hour scales, sine/cosine calculations, and a shadow square. The unequal hours are located in the upper left quadrant. The sine/cosine scale is found in the upper right quadrant, while the shadow square occupies the lower sections, with specific divisions marked in fingers for each face of the square.
- Provenance and History
- The astrolabe entered the Bodleian Library in 1659 as part of the manuscript collection bequeathed by the jurist, antiquary, and Member of Parliament for Oxford University, John Selden (1584–1654). The object remained with the library until it was transferred to the History of Science Museum in 1952. The records note an inventory number of 37527 and an accession number of 1952-76.
- Construction and Design
- The astrolabe is constructed primarily of brass. Its main body comprises a mater and limb formed from two pieces, which are joined through a soldered and riveted construction. The throne follows a compass-bearing style and is secured to an integrated base; it remains otherwise undecorated. The suspension system consists of a plain ring with a circular cross-section, complemented by an eye-bolt shackle that pivots within a round bracket attached to the throne. A teardrop-shaped guide, intended for suspension, is positioned near the ring. The instrument's rete is a simple indicator-line type. Its star pointers predominantly feature trefoil-shaped bases, and it is fitted with four silver rotational knobs. The accompanying alidade is double-ended, featuring original, rigid, single-pinhole sights. Eight plates are provided for the instrument, covering latitudes up to 45 degrees. The womb of the instrument remains blank.
Identification
- Inventory Number
- 37527
- 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.
Research required
- Research required: The exact dating remains uncertain as indicated by the 16th-century (?) classification
- Research required: The hole in the throne is missing its original compass