Rocking Bar keyless watch mechanism
Record status
Individual type · partial
Period
circa 1870
Catalogued under object number 1920-539 in the Science Museum Group Collection, this spring-driven keyless watch mechanism dates to circa 1870. Sourced from the Bruno Roberts Collection, the brass movement features a rocking bar keyless mechanism and a detached lever escapement according to source records.
The uncased movement is displayed with the dial side exposed, revealing its brass plate, motion work, rocking bar winding and setting assembly, central hands, and a small subsidiary pointer.
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 1870
- Type
- spring-driven keyless watch mechanism , lever escapement and detached
- Credit
- Bruno Roberts Collection
Design
- Visible features
- • Circular brass movement plate shown from the dial side without a dial plate. • Exposed rocking bar keyless mechanism including steel winding and setting wheels, rocking lever, and jumper spring. • Central pierced hour and minute hands mounted at the center arbor. • A single blued steel pointer mounted at the subsidiary dial position in the upper-left quadrant. • Hand-scratched watchmaker markings or numerals visible in the upper-right section of the plate.
- Identity and Provenance
- This object is catalogued in the Science Museum Group Collection under object number 1920-539 with the title 'Rocking Bar keyless watch mechanism'. The institutional record classifies its type as 'spring-driven keyless watch mechanism , lever escapement and detached' and assigns an estimated date of 'circa 1870'. Provenance is noted through a credit line to the 'Bruno Roberts Collection'. Neither a specific maker nor a place of origin is recorded in the museum documentation.
- Keyless Work and Mechanical Details
- Visible on the dial side is an exposed rocking bar keyless mechanism consisting of steel winding and setting wheels, a pivoting rocking lever, and a jumper spring. While the museum record describes the movement as having a detached lever escapement, only the dial side is shown in the provided photograph. The train, escapement, and balance assembly situated on the rear plate are not visible, leaving those structural details unobservable in the image.
- Dial Side Construction and Indications
- The uncased circular brass movement plate is shown from the dial side without a dial plate mounted over the work. It features central pierced hour and minute hands mounted directly at the center arbor. In the upper-left quadrant, a single blued steel pointer is fitted at a subsidiary dial location. In the upper-right section of the plate, faint hand-scratched watchmaker markings or numerals are visible on the metal surface.
Identification
- Object Number
- 1920-539
- 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 maker and country of origin are not recorded in the source.
- Research required: Only the dial side of the uncased mechanism is shown in the provided photograph; the gear train and escapement on the rear plate are not visible.