A device comprises a basic
clock movement MB whose time indicators are driven by a first
barrel connected to a first wheelwork and a first
regulator organ, and an autonomous chronograph module MCA whose indicators are driven by a second
barrel independent from the first, connected to a second wheelwork and a second
regulator organ. The chronograph module is exclusively composed of
mechanical elements. The frequency of oscillation supplied by its
regulator is equal N times the frequency of oscillation supplied by the regulator of the base movement, with the coefficient N being definable according to a specific application of the chronograph, so that any chronograph module thus previously defined can work with the same base movement. The chronograph regulator remains constantly engaged with the corresponding wheelwork. The chronograph module allows a time interval to be read with a minimum precision of a hundredth of second. The organs of the base movement and of the chronograph module are arranged in such a way that in assembled state, the height and overall
diameter do not exceed 7.75 mm and 30 mm respectively, the dimensions of the chronograph itself being not greater than 4 mm (height) and 30 mm (
diameter) when its elements are mounted on a bottom plate, so that the device can advantageously be integrated in the case of a
wrist-watch and affords an aesthetic exterior.