Astrolabe by Thomas Gemini
Record status
Individual type · partial
Period
1559
This 1559 brass astrolabe was produced by the craftsman Thomas Gemini in London. The object features a simple throne with s-shaped scrollwork, engraved with dedications to Queen Elizabeth I and bearing her coat-of-arms along with the Latin inscription 'Elizabeth Dei Gratia Angliæ Franciæ & Hiberniæ Regina etc.' The device incorporates an arsenius-type rete with three-dimensional strapwork and twenty-eight star pointers.
The womb contains a windrose and a 'Quadratum Nauticum'. It is assembled with a central nut and bolt, and includes an alidade and rule for the universal planisphere.
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
- 1559
- Type
- Latin-inscribed astrolabe
- Maker
- Thomas Gemini
- Material
- Brass
- Rete Type
- Arsenius
- Provenance
- University of Oxford, Savilian Collection
- Inscriptions
- Elizabeth Dei Gratia Angliæ Franciæ & Hiberniæ Regina etc.
- Place recorded
- London
- Maker / attribution
- Thomas Gemini
Design
- Visible features
- • The rete exhibits distinct three-dimensional strapwork rather than mere engraved shading • The throne is engraved with the royal coat-of-arms of Queen Elizabeth I • The womb includes a windrose and a 'Quadratum Nauticum' grid • The alidade is double-ended, counter-changed, and original to the instrument
- Construction and Design
- The astrolabe is constructed primarily of brass and features a three-piece construction for the mater and limb. The throne is of a simple type, attached via an integrated base, and decorated with s-shaped scroll work on both sides. The device is assembled using a central brass screw and washer mechanism. The rete is characterized by its arsenius style, which utilizes true three-dimensional strapwork to distinguish the interlacing patterns, rather than relying on engraved shading. It features twenty-eight stars marked with pointers and contains an ecliptic scale with divisions every five degrees.
- Inscriptions and Royal Provenance
- The instrument is engraved with royal iconography relating to Queen Elizabeth I, including her coat-of-arms and a formal Latin dedication. The inscriptions on the throne and womb identify the maker as Thomas Gemini and the year of manufacture as 1559, coinciding with the Queen's coronation year. Historical records from 1559 link the instrument to the household accounts of Robert Dudley, who made a payment to Gemini for an astronomical instrument. The object later entered the possession of John Greaves, Savilian Professor of Astronomy at Oxford, who utilized the astrolabe for scientific measurements during his 1637–1640 journey to the Levant.
- Provenance and Collection History
- The astrolabe was part of the Savilian Collection at the University of Oxford. Following its use by John Greaves, the instrument was presented to the university by his brother, Nicholas Greaves, in memory of John Greaves and John Bainbridge. The instruments were historically kept in the Savilian Tower's 'astronomy chamber' before being transferred to the University Observatory. The collection was identified and catalogued in 1936, at which point the astrolabe was assigned the inventory number 42223.
Identification
- Inventory Number
- 42223
- 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 identity of the original commissioner remains unverified, although likely to be Robert Dudley
- Research required: The specific purpose of the payment to Gemini in Dudley's 1559 accounts is stated as 'unspecified'