The reference 130, launched commercially in 1934, is a single-push chronograph using the calibre 13. It is equipped with two subsidiary dials, one indicating the seconds up to the minute and the other the minutes up to the half hour.
Produced from 1940, the reference 1491 is a watch without chronograph with a more elegant design than the already classic Calatrava. Released in 1941, the reference 1518 introduces commercially a tantalizing combination of complications, paving the way for the 2499 that replaced it in 1951.
Some sensational prototypes are prapared during this period. In 1942 the reference 1554, known in only two units, modifies the 1491 to insert a chronograph. In 1943 the reference 1527, not communicated in period to the public, manages to improve the aesthetics of the 1518. It was also made in only two copies, among them a unique example with a chronograph which was sold for CHF 6.25M including premium by Christie's on 10 May 2010.
These refinements interest professionals in specific applications. In 1938 a sports commentator specializing in boxing bought a 130 made in 1937, which obviously interested him for its 30-minute chronograph.
Advances in broadcasting create new needs. When his watch returns to the factory for servicing in 1942, it is reassembled as a 1491 with a slightly wider and thicker casing than the basic 1491. The dial is modified especially for this customer by an oversizing of the 30-minute sub-dial.
This wristwatch is estimated US $ 500K for sale by Christie's in Dubai on March 22, lot 177. It is the only known example of a chronograph in the reference 1491. The simultaneity of its design with the ephemeral 1554 cannot be a chance.