Quadrant by Robert Dudley
Record status
Individual type · partial
Period
1597
This brass quadrant, measuring 370 mm in radius, was signed and dated by Robert Dudley in 1597. It is a navigational and astronomical instrument densely engraved with various scales for timekeeping, solar and lunar calculations, and celestial tracking.
The front face features a limb with a scale of degrees, tables for the solar cycle, dominical letter, and epact, a zodiacal scale, and a calendar for the date of Easter. The centre displays hour lines, solar latitude scales, and the named tropes of Cancer and Capricorn, alongside planetary hours. The reverse side includes a shadow square, a wind rose with 32 directions, and a calendar scale paired with an additional zodiac scale.
A central hole is present, interpreted as a pivot point for a sighting vane or alidade. The instrument originates from the Dudley bequest and is held in the collection of the Istituto e Museo di Storia della Scienza in Florence.
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
- 1597
- Type
- English quadrant
- Maker
- Robert Dudley
- Radius
- 370 mm
- Material
- Brass
- Inscription
- Sir Robert Duddeley was the Inventer of this Instrument Ano 1597
- Place recorded
- England
- Maker / attribution
- Robert Dudley
Design
- Visible features
- • Signature of Sir Robert Dudley dated 1597 visible on the obverse face • Engraved hour lines and zodiacal information • Central hole present for potential alidade attachment • Brass construction with alternating shading on scales
- Reverse Face Features
- The back of the quadrant repeats the degree scale on the limb, but shifts focus to terrestrial and further temporal measurement. It incorporates a shadow square, which is divided to 5 and 1 and numbered from 1 to 60. This component is labeled as 'VMBRAE RECTAE' and 'VMBRAE VERSAE', with an inner side numbered continuously across the edges. Occupying the interior of the shadow square is a wind rose featuring 32 directions, with the north marked by a fleur-de-lis. Surrounding this are two further concentric scales: a calendar scale with month names in Latin, and a zodiac scale indicating the position of the sun, where the first point of Aries is set to March 10.
- Front Face Configuration
- The obverse of the quadrant is dominated by a limb engraved with a degree scale divided to one-quarter degree increments. Near the apex, multiple tables provide astronomical data, including the solar cycle, dominical letter, epact, and the lunar cycle. A zodiac scale is also positioned near the apex, displaying names and symbols, complemented by a signature identifying Robert Dudley as the inventor. The central field of the quadrant contains hour lines numbered from 1 to 12 and an unequal scale representing the sun's latitude. The major celestial boundaries, specifically the tropics and the equator, are explicitly marked. Furthermore, the instrument displays planetary hours and a double concentric circle containing the date.
- Provenance and Physical Condition
- The instrument is part of the Dudley bequest and is currently managed by the Istituto e Museo di Storia della Scienza in Florence. The brass surface features intricate engraving, including alternate shading on various scales to facilitate reading. A central hole is present, which is noted by the museum records as a feature possibly intended for the mounting of an alidade. The overall design includes tables for the calculation of the date of Easter, known as the 'Tabula Pascalis', and a multi-decade list of cycles covering years from 1539 to 1868. This extensive information suggests the quadrant was intended to function as a long-term astronomical reference tool.
Identification
- Inventory Number
- 3365
- 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 function of the central hole is described only as a possibility for an alidade
- Research required: Specific purpose of numerical values in the centre of the wind rose remains unexplained