Important Collectors Wristwatches, Po...

Geneva, Nov 14, 2009

LOT 20

Siderograph Longines Watch Co., ?Service Hydrographique de la Marine?, No. 5789255. Made circa 1943. Very fine and rare aluminium, siderograph with center-seconds, seconds recorder, split-seconds, 36-hour power reserve indication and stop feature, in a gimballed mahogany deck box.

CHF 7,000 - 9,000

USD 7,000 - 9,000 / EUR 4,700 - 6,000

Sold: CHF 10,800

C. Deck box with brass bound corners, aluminium gimbal and external start-stop for the chronograph. Inner: Cylindrical, massive, back secured by five screws, chronograph pushbutton at 8 o'clock, knob for setting revolving 60 seconds dial at 5 o'clock, winding/setting stem at 12 o'clock, start/stop lever at 10 o'clock, glazed back removable screw-on weight to work with the gimbals. D. Two-tone, silvered, black Arabic numerals, outer minute track, with outer revolving blue chronograph ring, power-reserve sector below the 12. M. 21''', Cal. 21.29, rhodium-plated, fausses cotes decoration, 17 jewels, straight-line lever escapement with beryllium pallet fork, monometallic balance, self-compensating blued steel Breguet balance spring with micrometric cam-type regulator, chronograph work visible on the back plate. Dial, movement and deck box signed. Deck box: 15.3 cm x 15.3 cm x 100 cm. Inner: Diam. 94 mm.


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Grading System
Grade: AA

Very good
Case: 3-9-10

Good

Scratched

Patinated
Movement: 2

Very good
Dial: 3-9-01

Good

Scratched

HANDS Original

Notes

Invented by Longines in 1938, the ?Siderograph? measures Greenwich (0 longitude) Sidereal or Civil Time in hour angles, minutes and minutes of arc, and can be considered the final evolution of the marine chronometer. These timepieces allow the user to navigate at night as well as during the daylight hours more accurately than the Weems and Lindberg systems for nocturnal navigation that were heavily reliant on radio time signals. The ?Siderographs? were based on the chronometer calibre 2129 which was at the time Longines's most accurate movement. The caliber was modified with the addition of the split-seconds mechanisms and anti-magnetic beryllium pallet fork. The movement was then cased in a heat-toughened aluminum case. This is a non-magnetic, light, nonferrous material suited for use for use in :aeronautic and maritime applications. The present lot is one of a handful of examples known to exist in a gimballed deck box, an indication it was intended for use aboard a ship.