4068 - Pocket watch: extremely rare double-wheel Debaufre escapement, Patry, Geneva, circa 1820: Approx. Ø48mm, ca. 84g, original silver case, case and movement share the same number 6726, one of the rarest escapements, pallet marked "Patent Jewelled Vertical", large balance wheel, mainplate and dial signed M. Patry, enamel dial, gold hands, small seconds, in working order. The Debaufre escapement is a rare, historical watch escapement with deadbeat friction, invented in London in 1704 by the French watchmaker Pierre (Peter) Debaufre. It is regarded as one of the earliest modifications designed to apply the deadbeat principle to pocket watches. Due to its visual operation and regional prevalence, it is also known in the English-speaking world as the "Chaffcutter", "Ormskirk" or "Club-footed verge". Two identical, mirror-image escape wheels are mounted offset on the same shaft. The teeth of the two wheels alternately engage with the pallet. Whilst one tooth rests on the flat underside (rest phase), the next tooth slides over the sloping surface of the pallet as it oscillates, imparting a driving impulse to the balance wheel.