Important Watches, Collectors’ Wristw...

Hotel Noga Hilton, Nov 14, 2004

LOT 433

J. Hammersley, To the Admiralty, ?Inventor and Maker of the Duo-in-Uno Balance Spring?, 14 Barclay Rd., London, No. 1/4018, hallmarked 1888-89. Very fine and rare 18K gold, half-hunting, keyless minute-repeating watch with chronograph, 30-minute register and duo-in-uno balance spring.

CHF 20,000 - 25,000

EUR 13,000 - 16,000 / USD 16,000 - 20,000

C. Five-body, ?bassine?, engine-turned, front with aperture encircled by champlevé radial Roman numerals, back with engraved initials, gold hinged cuvette. D. White enamel, radial Roman numerals, outer minute divisions, outermost chronograph track divided into fifths, minute register at 12, subsidiary sunk seconds at 6. Blued steel ?spade? hands. M. 44 mm, 3/4-plate, frosted gilt, jeweled to the center, lateral counterpoised lever escapement, cut-bimetallic compensation balance with gold screws and blued steel duo-in-uno balance spring, repeating on gongs through activating slide in the band.Dial and movement signed.Diam. 55 mm.


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Grading System
Grade: AAA

Excellent
Case: 3

Good
Movement: 3*

Good

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

Notes

The duo-in-uno balance spring enables one to lower the height of a helical spring. John Hammersley is also credited with the invention of the trio-in-uno balance spring, in which a spiral form is made on both ends, forming a closed cage. They are dfficult to make and therefore extremely rare. John Hammersley 1819-1901 Was an excellent watch and chronometer maker who made movements for Dent, and deck watches for the Admiralty.