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.