Paul Perregaux And The Rolex Twin Lock.

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In the early 1920s, a famous Swiss casemaker, Francis Baumgartner, made cases based on a patent by Borgel. The idea involved sealing the case by taking the middle part and threading it on both sides, rotating in opposite directions. The movement and dial then were fited within a ring that screwed into the caseframe. Several companies then used Baumgartner-made cases in the 1920s, including Omega and Longines. However, the Borgel-based cases did not seal well at the stem opening. To solve that, two Swiss watchmakers in La Chaux-de-Fonds, Paul Perregaux and Georges Peret, applied for a Swiss patent in 1925 for a screwed stem watertight system .

Hans Wilsdorf of Rolex grasped that a hermetically sealed case, together with careful fitting of the crystal and the aquired special stem mechanism, would produce a better waterproof wristwatch. He quickly negotiated to have the Perregaux and Peret patent assigned to him. Wilsdorf then obtained a British patent on October 18, 1926.Mr Wisdorf was a very shrewd business man Drawings from the patent are shown below.


The Rolex Oyster was born and became a commercial success.. In 1927, a stenographer, Mercedes Gleitze, swam the English Channel with the unheard of accompaniment of a wristwatch –the Rolex Oyster— on her wrist for the entire 15 hour, 15 minute, swim.
http://people.timezone.com/mfriedber...der_water.html

1.Picture is Paul Perregaux silver case hallmark is 1924
I bought this from Eddie Platts,a few years ago.

2.Perregaux & Perret twin lock patent