Valjoux 23

History: Designed in 1916, the first Valjoux caliber 13, or VZ, began life as a mono-pusher chronograph utilizing a mechanism developed in 1846 by Adolph Nicole and Henri Féréol Piguet. A simple calendar complication was developed on the heels of the initial chronograph with the core design remaining in production in one of its many forms until 1974 – an astonishing 58 year run.

This is a 17-jewel, 13-ligne (about 29.5mm diameter), hacking and flyback movement of traditional column-wheel design. The 1976 technical specs for this movement can be obtained in this PDF.

Manufacturer: Valjoux (for Vallée de Joux, "Joux Valley") is a Swiss manufacturer of mechanical watch movements. It is known primarily for chronograph ébauche movements that are used in a number of mid- to high-range mechanical watches: The company has been a part of ETA for a number of years and is a member of the Swatch Group.

Valjoux SA was founded in 1901 by the brothers John and Charles Reymond in Les Bioux and until 1929 operated under the name "Reymond Frères SA". The company specialized on chronograph movements. In 1910 it moved to a factory building maintained by the municipality of Les Bioux. The company's famous column wheel chronograph movement, Calibre 22, debuted in 1914 and lasted in production for sixty years. But it was larger than desirable for wrist watch use. The military, involved in the First World War, required reliable bracelet chronographs. Thereafter the 13-ligne chronograph Calibre 23 (diameter 29.33 mm, height 5.85 mm) was developed, which in 1916 came to the production stage and soon ticked in the wristwatches of very different manufacturers (for instance Audemars Piguet, Patek Philippe, Rolex, and Vacheron Constantin). The production lasted nearly sixty years, and until 1974 about 125,000 ebauche movements of this type were made.