Equinoctial Dial by Petrus ab Aggere
Record status
Individual type · partial
Period
1562
This equinoctial dial, crafted from gilt brass, measures 11 x 57 x 57 mm and was produced in Madrid in 1562. Signed by Petrus ab Aggere, the instrument features a square form and includes an internal compass with eight directional points.
The lid's exterior is engraved with an hour circle marked 1 to 12 twice, alongside decorative arabesque spandrels and a Latin quotation from Matthew 25. The dial displays latitude tables on both the inner lid and the box bottom. Additional functional components include an unequal scale for latitudes on the right side and an instructional inscription regarding magnetic declination on the left and bottom edges. The outer edges of the instrument bear further inscriptions detailing the latitude settings, the maker's signature, and the date of production.
It is currently held in the Lewis Evans Collection 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
- 1562
- Type
- Equinoctial dial
- Maker
- Petrus ab Aggere
- Material
- Gilt brass
- Dimensions
- 11 x 57 x 57 mm
- Provenance
- Lewis Evans Collection
- Inscriptions
- Matthew 25
- Place recorded
- Spain (Madrid)
- Place of origin
- Madrid
- Maker / attribution
- Petrus ab Aggere
Design
- Visible features
- • The dial is hinged to allow the lid to act as an adjustable gnomon • The magnetic compass is recessed within the square box • Latitude scale on the side is calibrated from 20 to 60 degrees • The dial face is integrated into the underside of the folding lid
- Construction and Design
- The equinoctial dial is constructed from gilt brass and takes a square form, measuring 11 mm in depth and 57 mm in both width and length. The design incorporates a folding lid that functions as the equinoctial plane, which is decorated with arabesques in the spandrel spaces. The lid's outer face displays an hour circle numbered 1 to 12 in two sequences. The instrument integrates a compass featuring eight named directions, located within the base of the box. These features facilitate the alignment and orientation of the dial for timekeeping.
- Provenance and Attribution
- The object is signed by Petrus ab Aggere and carries a date of 1562, confirming its production in Madrid. The piece was formerly part of the Lewis Evans Collection, documented as item S. 6. The museum notes that the dial is comparable in form to another piece by Juan Cocart, a maker associated with Spain, which is also held in the collection of the Museum of the History of Science, Oxford.
- Inscriptions and Latitude Data
- The dial contains multiple instructional and moralizing inscriptions. The top border carries a quotation from the Gospel of Matthew 25, which serves as a memento mori. Further text, including instructions regarding magnetic declination, is found on the sides and bottom of the box. Latitude information is provided through tables located on both the inner lid and the bottom of the box. A latitude scale, divided by degrees from 20 to 60, is located on the right side of the instrument. The edge inscriptions clarify the purpose of this scale and identify the maker and date.
Identification
- Inventory number
- 35203
- 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 recipient 'D. Petri Fag iardi F.' remains unverified
- Research required: The functional precision of the magnetic compass in a contemporary setting is not documented