Gallet Clamshell

The Clamshell, manufactured between 1936 and 1951 by the Gallet Watch Company of Switzerland, is the world's first water resistant wrist chronograph.

Introduced prior to World War II as part of Gallet's MultiChron line of military and professional use timepieces, Clamshell watches are recognized by the presence of four screws on the reverse side of the case, located at base of the lugs that attach the watch to the band or bracelet. Most Gallet Clamshell chronographs measure 34.2 millimeters in diameter (not measuring the winding crown) by approximately 42 millimeters in overall length, with a few smaller and larger examples released during the 1940s.

The Clamshell's 15-year history began in 1936 when Gallet purchased the rights to a patent for the "waterproof" watch case design (Brevet N° 189190), invented by the Swiss firm of Schmitz Frères & Cie in the neighboring city of Grenchen. By inserting gasket sealed pushbuttons into the side of this unique watch case design, Gallet was able to expand the water resistant characteristics of the Schmitz Frères concept to the more complex wrist-worn chronograph. Originally engineered by Gallet for the adverse conditions of the battlefield, the Clamshell chronograph derived its nickname from the way that the upper and lower sections of the watch case compressed together over a specially flared crystal, protecting the delicate inner mechanisms from the intrusion of water, dirt, dust, and caustic chemicals.

The "waterproof" Clamshell filled such a critical void in the area of military, industrial, and sports related timekeeping that its popularity helped Gallet's overall sales of wrist-worn watches and hand-held timers exceed 100,000 units per year for over 15 years. Gallet also supplied privately labeled versions of its Clamshell chronograph to other watch companies, as well as retailers that included C. Bucherer of Lucerne, Türler in Zurich, Tiffany & Co. of New York, and T. Eaton of Canada. In spite of the Clamshell's effectiveness at preventing water intrusion to a submerged depth of over 100 meters, it was eventually replaced by more easily serviceable versions with full screw-on case backs and readily available generic crystals.

During the 15 years of the Clamshell's production, numerous dial or face variations were released. Styles ranged from basic military specification black to more exotic two-toned and multicolored versions with tachometer, telemeter, and heart rate indications. A relatively small number were released with luminous numbers, accompanied by radium-filled minute, hour, and sweep second hands for low-light conditions.

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