Azimuth Dial
Record status
Individual type · partial
Period
circa 1600
This brass instrument, measuring 145 mm in diameter, is configured as an azimuth dial with an integrated planisphere. Its construction follows the general form of an astrolabe, featuring a mater equipped with a simple throne and suspension ring.
The reverse side serves as the primary azimuth dial, displaying specific lines for solar declination and hour markings ranging from IIII to XII to VIII, with divisions at 20-minute intervals. The mater itself is engraved with a Gemma Frisius universal projection, with the ecliptic marked by zodiacal symbols. The instrument includes a semi-circular plate featuring a corresponding universal projection. An inscription on the azimuth dial attributes its invention to Sir Robert Dudley in 1598.
The instrument is currently held in the British Museum. The ruler and fixing mechanism are identified as modern replacements. This object is documented in the catalogue of European Scientific Instruments by F. A. B. Ward.
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
- circa 1600
- Type
- English azimuth dial
- Diameter
- 145 mm
- Material
- Brass
- Inscription
- An Azumoth dyall for the latitude 52 deg. invented by Sr Ro Duddeley Ano 1598
- Place recorded
- England
- Replacement parts
- Ruler and fixing mechanism
Design
- Visible features
- • Features a suspension ring at the top of the throne • Reverse side engraved with tropics and hour lines • Includes a central pivot point for the instrument components • Degree scales visible along the outer rim
- Construction and Layout
- The instrument is constructed from brass and measures 145 mm in diameter, mimicking the structural form of an astrolabe. A simple throne with a suspension ring is attached to the mater's rim. The rim itself is engraved with a double degree scale, including a 0 to 360 circle and a 0 to 90 quadrant arrangement, subdivided down to 1-degree increments. The reverse of the device functions as an azimuth dial. Engravings include labelled tropics for Cancer and Capricorn, as well as an equator indicated by a double line with alternate shading. Solar declinations are marked by lines with arrowheads at 5-degree intervals, further subdivided to 1 degree. The hour lines are numbered IIII through XII to VIII, allowing for 20-minute readings.
- Projection and Components
- The interior of the mater features a Gemma Frisius universal projection, with the ecliptic marked using standard zodiacal signs. This is paired with a semi-circular plate that reflects the same universal projection system. While the primary plate and mater are original to the instrument's construction, the ruler and the associated fixing mechanism are catalogued as later replacements.
- Inscription and Provenance
- The azimuth dial contains an inscription within the circle created by the marking for the Tropic of Cancer. This text specifies that the instrument was intended for a latitude of 52 degrees and attributes its invention to Sir Robert Dudley in 1598. The piece is currently part of the collection at the British Museum in London. The instrument was acquired by the British Museum in 1894. It is recorded in the institution's inventory as MLA 1894,6-15.2 and is included in F. A. B. Ward's catalogue of European Scientific Instruments published in 1981.
Identification
- Inventory number
- MLA 1894,6-15.2
- 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 ruler and fixing mechanism are reported as replacements
- Research required: Attribution of invention to Sir Robert Dudley relies on the accuracy of the inscription