Equinoctial Dial by Charles Whitwell
Record status
Individual type · partial
Period
1606
This equinoctial dial is constructed from gilt brass with a diameter of 62 mm. It was made by Charles Whitwell in London in 1606. The instrument functions as a universal equinoctial dial, incorporating a circular compass bowl with a hinged cover that features a central aperture for visibility when closed.
The dial assembly, which includes a folding gnomon with an integral latitude quadrant, is secured to the same hinge as the cover. The device features multiple functional components, including a circular calendar scale on the cover exterior, a table of primes and epacts on the interior, and a lunar volvelle with an aspectarium located on the underside of the compass bowl. The compass includes a hand-coloured printed card featuring a 32-direction wind rose.
The instrument was formerly part of the Lewis Evans Collection, inventory number 220, and is held by 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
- 1606
- Type
- English equinoctial dial
- Maker
- Charles Whitwell
- Diameter
- 62 mm
- Material
- Gilt brass
- Provenance
- Lewis Evans Collection 220
- Compass needle
- Modern replacement
- Place recorded
- England
- Maker / attribution
- Charles Whitwell
Design
- Visible features
- • The hour ring features both summer hours (I-XII, I-XII) and winter hours (VI-XII-VI). • The compass card is hand-coloured and features 32 wind directions. • The lunar volvelle on the underside includes a moon phase aperture and aspectarium symbols. • The signature 'Carolus Whitwell fecit' is engraved on the lower face of the hour ring.
- Lunar Volvelle and Provenance
- The underside of the compass bowl serves as a mount for a lunar volvelle. This assembly includes two fixed outer scales, one representing hours I to XII, I to XII, and the other a wind rose identifying 32 directions, with the 16 primary directions denoted by letters. Two rotating discs with pointers are mounted here. The larger disc displays a scale for the age of the moon, ranging from 1 to 29 1/2 days. The smaller disc contains an aspectarium featuring symbols for trine, quadrature, and sextile, along with an aperture designed to display the phases of the moon. The instrument entered the museum's collection through the Lewis Evans Collection, specifically item number 220.
- Dial and Navigation Components
- Fixed to the main hinge is an equinoctial dial assembly that recesses into the compass housing. The upper surface of the hour ring displays hours marked I to XII twice, subdivided into half-hours. The lower face is configured for winter hours, marked VI to XII to VI, and also includes the signature 'Carolus Whitwell fecit'. A folding gnomon is provided for setting latitude, featuring an integral quadrant graduated from 10 to 90 degrees. While a hole for a plumb bob is present, the bob itself is missing. The compass itself contains a hand-coloured, printed card displaying a wind rose with 32 directions and an outer degree scale marked 0 to 90.
- Construction and Exterior Features
- The instrument is fashioned from gilt brass and measures 62 mm in diameter. It comprises a circular compass bowl integrated with a hinged cover. The design incorporates a ring-shaped cover, which allows the user to view the internal compass even when the instrument is in the closed position. This cover is fitted with a catch to maintain closure. The external surface of the cover is engraved with a circular calendar scale. This scale identifies each month, which is then subdivided and numbered at 10, 20, and the final day of the month, with further subdivisions provided every two days. The internal face of the cover features a table of primes and epacts along with the engraved date '1606'.
Identification
- Reference
- 44225
- Inventory number
- 44225
- 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 blued compass needle is described as a possible modern replacement.
- Research required: A plumb bob is missing from the attachment point on the latitude quadrant.