Astrolabe
Record status
Individual type · partial
Period
Early 16th century
This unsigned astrolabe is constructed of brass and measures 115 mm in diameter. It is held by the Museum of the History of Science, Oxford. The instrument features a limb soldered to the back plate of the mater, with a throne, shackle, and suspension ring.
It includes a rete for 13 stars and three plates for various latitudes (37/40°, 43/46°, and 49/52°). The back features a degree scale, a zodiacal scale with symbols, and a calendar scale. The central area includes a double shadow square and a diagram of unequal hours, alongside a linear scale for sine calculation. The alidade is straight and fitted with double pinhole sights. The authenticity of the instrument remains uncertain, with reports noting stylistic inconsistencies in the engravings and non-standard features of the rete, though it is not definitively classified as a counterfeit.
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
- Early 16th century
- Type
- Astrolabe
- Maker
- Unsigned
- Alidade
- Straight with pinholes
- Diameter
- 115 mm
- Latitude plates
- Three plates for various latitudes
Design
- Visible features
- • The rete is engraved for 13 named stars. • The instrument features a throne, shackle, and suspension ring. • The alidade is a straight bar with double pinhole sights. • A double shadow square is present on the lower half of the back.
- Plates and Sighting
- The instrument includes three interchangeable plates covering six different latitudes. These are engraved with azimuths every 10 degrees and almucantars at 3-degree intervals. The layout includes meridian and east-west lines, as well as indications for tropics and the equator. The alidade is a straight design equipped with double pinhole sights. It is secured to the instrument via a threaded bolt and nut assembly.
- Construction and Layout
- The astrolabe is composed of a brass mater with a soldered limb and a central throne, shackle, and suspension ring. The limb contains a degree scale marked 90 to 0 in quadrants, divided to 1-degree intervals, alongside a 1 to 12 hour scale repeated twice. The central rete is designed for 13 stars and incorporates an ecliptic circle marked with signs. The back of the instrument hosts a similar limb scale, a zodiacal scale, and a calendar scale where the first point of Aries is marked at 10 1/2 March. A double shadow square occupies the lower central space, while the upper left contains a linear scale for calculating the sines of angles.
- Condition and Authenticity
- The provenance and physical condition of the astrolabe are subject to academic debate. Reports indicate that while some aspects appear medieval, the engraved letters reflect a later and non-standard style. The rete is noted for having a thick plate and incorrect divisions. The status of the instrument is not fully resolved; it may represent an eccentric, non-commercial production or an authentic piece with later modifications. Current findings suggest it is not necessarily a simple counterfeit.
Identification
- Inventory number
- 52528
- 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 auction description notes doubts regarding its authenticity.
- Research required: The engravings are reported to be in a later style inconsistent with other features.
- Research required: The rete is described as having an incorrect division.