French platinum hunting cased knife edged lever watch Circa 1917

Platinum gentlemen’s pocket watch
–
An ultra thin French platinum hunting cased knife edged (montre couteau) keyless dress watch, circa 1915-1920. Retailed by Tiffany & Co. in New York, U.S.A. The rhodium plated movement with a lever escapement and eight adjustments. Silver guilloché dial with Arabic hour numerals, an outer minute track and original Breguet hands. The plain, round shaped, case with a hinged cover. Dial signed by the retailer and watchmaker, movement signed by the watchmaker and case by the retailer.
–
Diameter: 49 mm
–
Thickness: 4.9 mm.
–
Signed: Cartier Paris – Tiffany & Co
–
Couteau is the term used by Cartier in their manufacturing records to describe the type of ultra thin watches with knife edged cases, open faced or hunting cased models. These watches, with thicknesses of less than 4 mm for the open faced and less than 5 mm for the hunting cased version, are among the thinnest mechanical watches ever produced.
–
For these thin watches from the first half of the 20th century, Cartier used movements from Edmund Jaeger (Jaeger-LeCoultre), who had just invented a movement only 2 mm thick. In the 1920s, Cartier and Jaeger formed a joint venture, the European Watch & Clock Co., whose signature can be found on many Cartier movements. Movements were further sourced from Vacheron & Constantin, who, from 1940, utilized a movement which was only 1.31 mm thick.