Important Collectors’ Wristwatches, P...

Geneva, Nov 16, 2008

LOT 490

Peto Cross Detent Escapement Brockbanks, London, No. 3791. The case with London hallmarks for 1825-1826. Very fine and extremely rare, 18K gold pocket chronometer with Peto cross detent escapement. C. Three-body, ?bassine?, No. 8919, mastermarkWW, engine-turned, flat band, the back cover with small central engraved monogram. Fixed gold cuvette engraved ?M.K. Hindmarsh?. D. White enamel with radial Roman numerals, outer minute track, large subsidiary seconds. Gold Breguet hands. M. 44 mm., matte gilt three-quarter plate with detachable plate for the barrel, cylindrical pillars, third, fourth and escapement pivots with jewels in screwed gold chatons, fusee and chain, Harrison?s maintaining power, Peto cross detent escapement with brass escape wheel, adjustable steel passing spring, three-arm bimetallic compensation balance with wedge-shaped brass weights retained by steel plates and screws, free movement of the bimetallic sectors limited by small screws in the free ends, steel timing screws, blued steel flat balance spring, diamond endstone, empty fixing holes on the barrel bridge for the amplitude limiting device. Movement signed. Diam. 51 mm.

CHF 9,500 - 13,000

USD 9,000 - 12,000 / EUR 6,000 - 8,000

Sold: CHF 9,600

C. Three-body, ?bassine?, No. 8919, mastermarkWW, engine-turned, flat band, the back cover with small central engraved monogram. Fixed gold cuvette engraved ?M.K. Hindmarsh?. D. White enamel with radial Roman numerals, outer minute track, large subsidiary seconds. Gold Breguet hands. M. 44 mm., matte gilt three-quarter plate with detachable plate for the barrel, cylindrical pillars, third, fourth and escapement pivots with jewels in screwed gold chatons, fusee and chain, Harrison?s maintaining power, Peto cross detent escapement with brass escape wheel, adjustable steel passing spring, three-arm bimetallic compensation balance with wedge-shaped brass weights retained by steel plates and screws, free movement of the bimetallic sectors limited by small screws in the free ends, steel timing screws, blued steel flat balance spring, diamond endstone, empty fixing holes on the barrel bridge for the amplitude limiting device. Movement signed. Diam. 51 mm.


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Grading System
Grade: AA

Very good
Case: 3-11

Good

Slightly worn
Movement: 3*

Good

Overhaul recommended, at buyer's expense
Dial: 2-01

Very good

HANDS Original

Notes

An amplitude limiting device consisting of a spring-loaded, pivoted lever, was once fitted to the barrel bridge of this watch; the fixing holes remain. Above a certain range of amplitudes, the expanding balance spring would push the lever sideways onto the path of a small steel piece carried on a balance crossing.
Peto?s Cross Detent Escapement Most surviving examples of the cross detent escapement are in chronometers signed Brockbanks. The escapement was invented by James Peto, who worked for the Brockbanks, around 1783-1784. Brockbanks John and Myles Brockbanks, pioneers of chronometry, were succeeded by their nephews, also named John and Myles. For a nearly identical movement see: The Time Museum Catalogue of Chronometers, A.G. Randall, Time Museum, 1991, pp. 112 & 113.