English Equinoctial Dial
Record status
Individual type · partial
Period
Late 15th century ?
This late 15th-century English equinoctial dial is an unsigned brass instrument measuring 40 mm in diameter. Housed within a compass box—now lacking the magnetic needle—it features a hinged lid and an adjustable hour ring.
The dial's design includes a pivoted cross-piece supporting the gnomon, which plugs into a small hole projecting from an internal brass band. The top of the lid incorporates a primitive nocturnal mechanism divided into twelve sections, each subdivided and engraved with letters potentially signifying months in Latin or Italian. The device is historically associated with find-site provenance in the river Crane at Isleworth and was donated to the British Museum by H.
C. Pidgeon in 1853.
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
- Type
- English equinoctial dial
- Diameter
- 40 mm
- Provenance
- Found in the river Crane at Isleworth
- Place recorded
- England
- Inscription type
- Pseudo-Chinese characters for cardinal directions
- Nocturnal feature
- Divided into 12 parts for monthly indication
Design
- Visible features
- • Hinged brass construction featuring a compass box base and circular lid • Hour ring graduated with Roman numerals IIII to XII and I to VIII • Lid exterior serves as a primitive nocturnal with alidade attachment
- Historical Attribution
- The dial is attributed to England and is dated tentatively to the late 15th century, though this dating remains speculative. It is unsigned, precluding any definitive identification of its maker or workshop. Although described as a universal equinoctial dial, the current configuration suggests it was functional for only a single latitude, which remains unidentified. The inclusion of 'pseudo-Chinese' lettering for the cardinal directions within the compass box suggests a non-traditional approach to the instrument's marking. Researchers noted that similar examples exist within the collection of the Museum of History of Science, Oxford, though no direct link between the specific manufacture of this object and other known pieces has been established.
- Provenance and Condition
- The instrument was recovered from the river Crane at Isleworth. Following its discovery, it was acquired by the British Museum in 1853 through a donation by H. C. Pidgeon. The object is officially registered as MLA 1853, 6-18.1 and has been documented in the catalog of European scientific instruments held by the Department of Medieval and Later Antiquities. The physical state of the dial is described as significantly worn. The surfaces exhibit extensive distress, which affects the clarity of the engravings and the overall integrity of the metal components. The internal compass remains empty, lacking the necessary needle for orientation. These factors combined indicate a long period of environmental exposure before the instrument's recovery and subsequent preservation.
- Structural Design and Dial Components
- The equinoctial dial consists of a circular brass compass box housing, which currently appears empty. A lid and an hour ring are mounted to the same hinge, allowing for the folding configuration of the instrument. The hour ring is engraved with Roman numerals from IIII to XII and I to VIII. It utilizes a pivoted cross-piece to which the gnomon is attached. To deploy the dial, the gnomon is inserted into a small hole projecting into the compass box from a ring, supported by a perpendicular brass band to maintain the required height. The lid of the object functions as a primitive nocturnal. This component is divided into twelve parts, further subdivided into smaller units, with each section marked by a letter, potentially representing months in Latin or Italian. A central pivot holds a double-ended alidade.
Identification
- Inventory number
- MLA 1853, 6-18.1
- 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: Original latitude adjustment capability is unclear as the design limits use to one unknown location
- Research required: Inscriptions within the compass box are identified as 'pseudo-Chinese'