A rare Regency one-day marine chronometer with Brockbanks ‘affix’ balance Brockbanks, …
Schätzpreis: 1.500 £ - 2.000 £
ca. 1.851 $ - 2.468 $
Zuschlagspreis: 2.800 £
ca. 3.456 $
A rare Regency one-day marine chronometer with Brockbanks ‘affix’ balance Brockbanks, London, circa 1810 The circular four pillar single chain fusee movement with Harrison's maintaining power, Earnshaw type spring detent escapement regulated by Brockbanks triple-arm split bimetallic ‘affix’ balance with helical balance spring and faceted diamond endstone, the backplate with blued-steel pillar and backcock securing screws and inscribed Brockbanks, London, No. 659, ONE DAY, with cylindrical brass internal dust cover similarly engraved to rear, the 3 inch circular white enamel Roman numeral dial with subsidiary seconds dial and signed BROCKBANKS, LONDON to centre, with Arabic five minutes within the outer minute track and gilt spade hands, fitted into a brass bowl with hinged moulded convex glazed bezel and shuttered winding square to underside, mounted via gimbals into a mahogany three tier box with gimbal locking plunger and tipsy key to interior, the front inset with oval ivory plate engraved 659 and the sides with hinged brass carrying handles, (top tier of box with damage), 16.5cm (6.5ins) wide. The firm Brockbanks was established when the two brothers John and Myles Brockbank went into partnership in the early 1790's. The firm was continued by various members of the family until becoming Brockbanks & Grove when George Grove was taken into partnership in 1812, later becoming Brockbank and Atkins when George Atkins was taken into partnership after Grove's death in 1814. The firm was well known for producing fine marine chronometers. A closely related chronometer by Brockbanks (number 632 featuring the same design of ‘affix’ balance) resides in the collection of the British Museum and is extensively described in Randall, Anthony G. and Good, Richard CATALOGUE OF Watches IN THE BRITISH MUSEUM, VI Pocket Chronometers, Marine Chronometers and Other Portable Precision Timekeepers on pages 93-4. Below is an extract describing the balance which is essentially the same as that of the current lot: “Bimetallic three-armed balance riveted to a brass collet. Limiting screws for the movement of the free ends of the bimetallic rims pass through clearance holes in the rims and into steel brackets integral with the arms. The outer sides of the rims are graduated with a series of inclined marks near their free ends. The brass compensation weights are fixed by a fitted plate, each with a screw and steady pin. Each weight has a brass screw set sideways on its outside, tangential to the balance; these are for fine adjustment of the compensation. Poising of the balance has been achieved by filing the undersides of the arms. Each steel timing screw set in the fixed ends of a rim has two holes in the end of the head instead of a screwdriver slot. Diam. of rim 29.7 mm, h. 2.17 mm.” The movement of number 632 is illustrated along with details of the balance and escapement in plates 49c-e; these images and the full catalogue entry are also available on The Bristish Museum website. Please note, this lot may be subject to CITES regulations if exported from the EU. The CITES regulations may be found at www.defra.gov.uk/ahvla-en/imports-exports/cites/ . Please note: The serial number engraved on the movement backplate reads 658 not 659 as indicated in the catalogue. Condition report disclaimer
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