Hebdomas, ca. 1930, 8 days pocket watch. Steel, with Jacob Bengel Art Deco chain.
The Hebdomas trademark was registered to Graizley & Cie, La Chaux de Fonds, Switzerland.
The Hebdomas 8 day watch was patented in January 1889. It was used on 8 day watches with a visible balance wheel. At first these 8 day watches were all made by hand. Hebdomas watches won gold medals in Chicago 1892, Geneva 1896, Paris 1900, Milan 1906 and Brussels 1910.
In 1915, the patent and tradename was transferred to Schild & Cie, the new name for the Graizely & Cie company.