An early 20th Century Swiss lever in a patent silver Borgel wristwatch case. Gilt three quarter plate keyless movement with going barrel. Plain cock with polished steel regulator, uncut bimetallic balance with spiral hairspring. Club foot lever escapement. Signed white enamel dial with subsidiary seconds, Arabic numerals, the twelve in red, luminous hands. Patent Borgel silver wristwatch case, the movement fitted to a threaded brass carrier and screwed into the case, ribbed bezel. Maker's mark “FGT” in a rectangle overstruck with Borgel's mark “F.B.” above a key.
Fran�ois Borgel first patented his design for a watch case in 1891. It was an early attempt to make watches resistant to dust and moisture. The case back and middle part are in one piece and threaded internally. The movement, complete with dial and hands, is mounted in carrier ring. The bezel with glass is used to extract it once the button has been pulled out against its spring. Borgel screw cases have been used by a number of manufacturers included Longines and the International Watch Co. The business was sold in 1924 to Taubert who carried it on until the 1970's supplying many watch manufacturers including Patek Philippe and Vacheron & Constantin