Escapement model by Emery, Josiah, England, 1792

Record summary

Held and catalogued by Science Museum Group, London (object number L2015-3484), this is a constant force escapement; chronometer by Emery, Josiah, made in London, Greater London, England, United Kingdom, London, dated 1792. The Atlas places it in the Precision & Scientific Horology period (1750 – 1850) of its Movements & Components collection. Recorded dimensions: overall: 165 mm x 122 mm x 71 mm. The record is illustrated with 2 photographs.

Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.

Catalogue description

Atlas type guide

Escapements and escapement models

The escapement is the heart of every mechanical clock and watch: it releases the gear train one tooth at a time and gives small impulses to the oscillator (pendulum or balance) to keep it swinging. The verge (thirteenth century), anchor (c. 1670), deadbeat (c. 1715), cylinder (1720s), lever (c. 1755), detent (1780s) and co-axial (1970s) escapements each solved problems of friction, recoil and isochronism in different ways.

Large demonstration models of escapements were made for teaching in horological schools, for patent applications and for exhibitions. They are valuable because they make visible, at large scale, the minute interactions that take place in a watch many times per second.

General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.

Read next:Verge escapementAnchor (recoil) escapementDetached lever escapementSpring detent escapementCo-axial escapementGrasshopper escapementEscapement simulation lab