Inclining Dial by Johann Christoph Keller
Record status
Individual type · partial
Period
circa 1600
This inclining dial, held by the Museum of the History of Science, Oxford, is signed by Johann Christoph Keller and dates to approximately 1600. Manufactured in Linz, the instrument consists of a brass plate integrated into a wooden case.
The brass dial is mounted on gimbals, allowing for adjustment to latitudes ranging between 45 and 55 degrees through the use of a sliding counterpoise positioned on the underside of the plate. A compass is set at the center, mounted on pivots to maintain a horizontal position regardless of the angle of the dial. Time is indicated by a string gnomon dial, with hours marked from IIII to XII to VIII, supported by a folding brass stand.
The signature of the maker is inscribed at the top of the dial plate. The wooden case, which features brass round feet, is described as appearing to be modern.
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
- Inclining sundial
- Maker
- Johann Christoph Keller
- Material
- Brass and wood
- Dimensions
- 113 x 116 x 67 mm
- Place recorded
- Linz
- Compass markings
- SE, OR, ME, OC
- Maker / attribution
- Johann Christoph Keller
Design
- Visible features
- • Dial plate mounted on gimbals • Folding brass gnomon stand • Cardinal points marked SE, OR, ME, OC • Modern wooden case with spherical feet
- Timekeeping Mechanism
- The time is indicated via a string gnomon, which creates the necessary shadow on the brass plate. The hour scale is marked with Roman numerals ranging from IIII to XII and continuing to VIII. To ensure the gnomon remains in the correct position for timekeeping, it is supported by a folding brass stand attached to the dial plate. The signature is prominently displayed at the top of the dial plate. The inscription, 'I ? CHRIST KELLER ? LINZI', identifies the maker and the location of manufacture as Linz, providing attribution for the origin of the instrument to the period around 1600.
- Construction and Design
- The inclining dial is constructed from a brass plate housed within a wooden case. The primary function of the instrument relies on a gimbal-mounted system that allows the plate to tilt relative to the horizon. Adjustment for latitude is managed through a sliding counterpoise located on the underside of the brass plate, accommodating a range between 45 and 55 degrees. The overall dimensions are 113 by 116 by 67 millimeters, supported by round brass feet. A central compass is integrated into the dial plate. This component is mounted on pivots to remain horizontal during operation, irrespective of the angle of the main dial. The compass dial is marked with cardinal points abbreviated as 'SE', 'OR', 'ME', and 'OC' and includes declination markings to facilitate orientation.
- Condition and Attribution
- The instrument is catalogued under the inventory number 35317 at the Museum of the History of Science in Oxford. Documentation provided by the museum indicates that the wooden case, which contributes to the current aesthetic of the object, is not original. It is explicitly noted in the records that the wooden case with its round brass feet appears to be modern in origin. The attribution to Johann Christoph Keller of Linz is derived from the signature present on the dial plate itself. The dial is classified as an inclining dial, which utilizes the aforementioned gimbals and counterpoise to compensate for different latitudes,
Identification
- Inventory number
- 35317
- 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 wooden case is noted as appearing to be modern
- Research required: Latitude adjustability range specified as 45 to 55 degrees