Astrolabe, circa 1570
Record status
Individual type · partial
Period
circa 1570
This unsigned brass astrolabe has a diameter of 232 mm and comprises a mater, rete, latitude plates, rule, and alidade. The mater features a squat throne with a shackle and suspension ring.
Its limb contains hour divisions and a degree scale alongside French names for sixteen compass points. The rete follows the Arsenius type in tracery, featuring a tulip motif and 25 named stars, with an ecliptic circle marked by zodiacal signs. Two latitude plates provide projections for 45, 47, and 48 degrees, with one side displaying a universal projection of the Gemma Frisius type. The back includes a calendar scale, a double shadow square, and a conversion diagram for equal and unequal hours.
The assembly includes a pin that engages with a sliding washer. The instrument is held at the Museum of the History of Science, Oxford.
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 1570
- Type
- French astrolabe
- Diameter
- 232 mm
- Material
- Brass
- Rete type
- Arsenius
- Compass points
- 16
- Place recorded
- France
- Attributed country
- French
Design
- Visible features
- • Squat throne with shackle and suspension ring • Arsenius-type rete with tulip-motif tracery • Degree scale on limb numbered by 10 • Double shadow square on the instrument's back
- Construction and Mater
- The astrolabe is constructed of brass and measures 232 mm in diameter. The mater is fitted with a squat throne, which supports the shackle and suspension ring. The back plate is secured to the main body by rivets. The limb features a complex series of markings, including hour divisions from 0 to 12 twice, indicated by Roman numerals, and a degree scale running from 0 to 360, divided into single-degree units. A notable feature is the interior of the mater, which contains a latitude projection for 43 degrees. This includes azimuths and almucantars, as well as markings for the 12 houses labeled 'I DOMVS' through 'XII DOMVS', beginning from the eastern horizon.
- Rete and Latitude Plates
- The rete is designed in the Arsenius style, featuring intricate tracery with a tulip motif and displaying 25 named stars. The ecliptic circle is marked with names and symbols of the zodiacal signs, each provided with a 30-degree scale. The instrument is equipped with two latitude plates providing projections for 45, 47, and 48 degrees. These plates feature azimuths and almucantars numbered by 10. A significant variation in the design is the inclusion of a universal projection of the Gemma Frisius type on the back of one of the latitude plates for 48 degrees. This plate displays lines of right ascension and declination, as well as additional star and ecliptic markings. The configuration represents a blend of familiar elements in an unconventional arrangement, drawing on both Flemish influences and French characteristics.
- Back Plate and Accessories
- The back of the instrument carries an outer degree scale that serves both for angular measurements and as a base for a zodiacal scale. Accompanying this is a calendar scale with Latin month names, divided into days. The central area contains a double shadow square and a conversion diagram used for equal and unequal hours. The rule has shaped ends and is fixed with an attached pin, featuring a linear scale divided into 10-degree increments and marked with zodiacal signs. The counterchanged alidade is marked with a scale of hours on one arm. The central assembly is secured by a pin that engages with a sliding washer, completing the functional requirements for the astrolabe's operation.
Identification
- Inventory number
- 49726
- 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 French origin is based on the uncertain significance of the compass point names
- Research required: The universal projection's placement on a latitude plate is an unusual configuration