Dent Demonstration Model of the Earnshaw Chronometer Escapement
Record status
Individual type · partial
Period
circa 1880
This circa 1880 demonstration model of an Earnshaw chronometer escapement was produced in London by Dent. Intended for display purposes, it was formerly held in the premises of E.
Dent & Co. The object features a vertical arrangement with the gear train secured between bridges on a brass bar. The going train is powered by a small gilded barrel wound via a knurled button, providing approximately one hour of duration. The wheels are gilded and fixed to lantern pinions with screws. The escapement mechanism follows the Earnshaw pattern, utilizing a polished steel spring-detent, a steel locking pin and roller, and a gold-alloy passing spring.
The balance staff is equipped with blued-steel end-plates, while the plain brass balance includes adjustable circular weights and timing screws. The assembly is completed with a helical blued-steel spring and is free-sprung with terminal curves, mounted on a turned mahogany base.
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 1880
- Type
- Demonstration model
- Maker
- Dent
- Height
- 25 cm
- Mounting
- Turned mahogany base
- Power reserve
- Approximately one hour
- Place recorded
- London
- Escapement type
- Earnshaw pattern
- Maker / attribution
- Dent
Design
- Visible features
- • Vertical train layout between bridges on a brass bar • Gilded wheels attached to lantern pinions via screws • Helical blued-steel balance spring
- Provenance and History
- The object is documented as having been held on the premises of E. Dent & Co., a firm founded by Edward John Dent. This specific model serves as an example of the tools used by the firm in their London operations. Its historical path includes a sale conducted by Christie's in London on 8 November 1972. The model was sold as lot 112 during that 1972 auction, upon the instructions of the Dent firm. The item currently remains identified by its historical association with the display of the Earnshaw chronometer escapement mechanism.
- Construction and Layout
- The demonstration model is constructed with a vertical orientation, placing the gear train between bridges mounted on a central brass bar. The wheels within the train are gilded and secured to their respective lantern pinions using screws. This configuration allows for the viewing of the escapement action and the transmission of power. Power is provided by a small gilded going barrel, which is wound through a knurled button. This mechanism is capable of sustaining movement for a duration of approximately one hour. The entire vertical assembly is mounted onto a turned mahogany base, which was historically accompanied by a glass dome.
- Escapement and Balance Mechanism
- The model features an Earnshaw-pattern chronometer escapement designed for demonstration. It incorporates a polished steel spring-detent and a steel locking pin and roller. The passing spring is described as being made of a gold alloy, although the source notes this with uncertainty. The balance assembly utilizes a plain brass balance fitted with adjustable circular weights and timing screws. The movement uses a helical blued-steel spring, which is free-sprung and finished with terminal curves. The balance staff is supported by blued-steel end-plates, contributing to the specialized construction required for this type of precision chronometric display.
Identification
- 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: Gold alloy composition of the passing spring is identified with a question mark in the source
- Research required: The total height of 25cm excludes the glass dome