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Extremely rare and important double-cased or Hermetic early dustproof wristwatch in solid sterling silver with superb white enamel dial and high quality Swiss made movement. This ingenious design, patented by Jean Finger in 1921, is a truly significant early attempt at fully "protecting" a wristwatch mechanism from moisture, dust and dirt by encasing the inner house entirely inside a second outer shell. Not only a revolutionary idea, but a precursor to the famous Rolex Oyster wristwatch, patented a full 5 years later in 1926. This particular example has the all the correct stamps attributing the design to Jean Finger, including a JF hallmark and the inscription "Double Boitier, Brevet+89276, Hermitique, Swiss Made". To wind the watch the wearer unscrews and removes the complete upper bezel and glass to reveal the inner case within. Then using your finger nail under a small tab at 4:00 the watch is hinged upwards so the movement can be wound and set as usual using the crown at 3:00. Once the watch is placed back down inside the lower shell and the bezel screwed back into place, the inner mechanism is, in truth, quite well "sealed" inside protecting it from dust and moisture. A further testemony to the importance of this design is that in the years after Jean Fingers patent, a number of major manufacturers including Rolex, Zenith and Eberhard produced watches using this case design. The museum quality example you see here is in stunning condition throughout on what looks like its original soft suede hand stitched leather strap. A truly important surviving representative of this critical innovation in watch-making history.
To learn more about the evolution of the waterproof wristwatch including details of the Jean Finger patents click here to read a wonderful article researched and written by David Boettcher of the UK from which much of our information has been sourced.
Style: Early Wristwatch, Military
Case: Stunning solid sterling silver hermetic case with outer shell protecting a second complete inner case hinged inside. Measures 34mm in diameter and comes on what appears to be the original hand stitched black suede leather strap with steel buckle on the 6:00 side. Stamped inside the outer case 0.925, Double Boitier (French for "Double Case"), Brevet + 89276, Hermetique, Swiss Made, JF. The inner case back is also sterling silver and fits perfectly but bears some different hallmarks, which to me means it is probably not original and was replaced at some point. It does not affect the overall look, or historical significance of the watch in my mind, but does mean the watch should not be considered "all original" (a factor which I have taken into consideration when pricing this rare example). The two crystals are also mineral glass, the inner I believe to be original but the outer was refited to perfection by our watchmaker with a new old stock replacement.
Dial: Original bright white enamel dial with Arabic numbers and skeleton hands, still bearing some of their original radium filling. Superb condition throughout with no hairlines or chips.
Movement: High quality manual wind movement with 15 bright red ruby jewels, bi-metalic cut balance, Breguet over-coil hairspring and a triple finger bridge plate design. Signed on the lower plate "Swiss Made". Freshly serviced by our watchmaker and in excellent working condition.
Note: It should be noted that while this was a worthy attempt at "water-proofing" in the early 1920's, in today's world it would perhaps be more accurately considered a "water-resistant" design due to the fact that without a good rubber or lead gasket to seal the join, it would almost certainly not remained dry inside if submerged for any longer than a few moments.