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The Encyclopedia of Horology

Glossary · Mechanism

Cylinder escapement

A frictional-rest watch escapement in which the escape-wheel teeth act on the rim of a hollow cylinder on the balance staff.

Explanation

In the cylinder escapement, associated with Tompion and perfected by Graham in the 1720s, the balance staff is formed as a hollow cylinder with a section cut away. Escape-wheel teeth enter and leave the cylinder, resting on its rim between impulses, so the wheel is locked for most of the balance's swing — a frictional-rest action. Impulse is given as a tooth slides across the cylinder's lip.

The design allowed much thinner watches than the verge and dominated continental watchmaking through the eighteenth and much of the nineteenth century. Its costs are friction at the rest surfaces, sensitivity to oil condition, and a delicate cylinder that is difficult to make and repair. It does not give the free-swinging balance of a lever or detent escapement, so a cylinder watch is not expected to hold rate like a lever watch of similar appearance.

Identification cues: a flat, toothed escape wheel with slender upright teeth, a balance staff carrying the cylinder, and typically a Swiss or French bar movement. Record the escapement from the movement, not from the case style; many cylinder movements sit in cases that look like lever watches of the same period.

Sources & references

  1. de Carle, D., Practical Watch Repairing — technical further reading; exact procedures require calibre documentation
  2. Reymondin et al., The Theory of Horology — construction and terminology further reading

Where sources disagree, the disagreement is stated rather than resolved silently.

Distinctions at a glance

FeatureCylinder escapementComparison
Rest actionFrictional rest on the cylinder rimLever balance swings free between impulses
ImpulseTooth slides across the cylinder lipLever impulses through fork and pin
Typical hostContinental bar movements, 18th–19th centuryEnglish full plate usually verge or lever
Rate expectationModest; sensitive to oil and wearNot comparable to a serviced lever watch

What to record

  • Identify the escapement from the wheel and balance staff, not the case.
  • Note cylinder condition as a specialist service item.
  • Keep rate expectations appropriate to frictional-rest action.

Never oil or prod the cylinder rim; the lips are thin and the escape-wheel teeth bend easily.

In the object catalogue

Catalogued objects whose own source record mentions “Cylinder escapement”. The quoted line shows where; it is the seller’s or museum’s wording, not independent verification.