Duplex Escapement
Also known as: Duplex watch escapement
Record status
Individual type · partial
Period
about 1700 onwards (patented form 1782)
The duplex is a watch escapement in which the escape wheel has two sets of teeth: long locking teeth projecting from the side of the wheel and short impulse teeth standing up from its face. A locking tooth rests against a small roller on the balance staff; as the balance swings, a notch in the roller releases it and the pallet receives a push from an impulse tooth. As in the detent escapement, the balance is impulsed during only one of its two swings.
It was difficult to make but, carefully made, approached the accuracy of the detent escapement. It was used in quality English pocket watches from about 1790 to 1860, and in the cheap American Waterbury watch from 1880 to 1898. The linked Victoria and Albert Museum example is a London watch of 1811-12 whose movement, by Smith & Asprey, Bruton Street, no. 3973, has a duplex escapement; the museum notes the movement is contemporary but not original to the case.
Evidence at a glance
- Linked sources
- 2
- 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
- Frictional rest watch escapement
- Impulse
- On one swing of the balance in each cycle
- Escape wheel
- Two sets of teeth: locking and impulse
Identification
- Identification
- Escape wheel with two tiers of teeth and a small notched roller on the balance staff.
- Source note
- Background drawn from Wikipedia ("Escapement"), a tertiary source, and from the linked V&A object record; not yet checked against a standard horological reference.
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: confirm details against a standard horological reference.