Abstract: The mechanism comprises a date-disc (8) actuated at midnight by a lever (1) supporting a rotary part (3) with catches (3a) gearing with the wheel (4) of 24 h. The mechanism is so designed that each transition from a date to the next is effected in less than one hour so that the calendar remains still in synchronism with the hours hand, even in the case of the changing of the indication of time-zones. The disc comprises pins (14) controlling at the end of each month through a star-wheel (13) the rotation of a first (17) and a second (20) cam. The cams bear finger-pieces (17a,17b,21) the ones (17a,17b) of the first cam having variable widths according to the different lengths of the months forming bankings for a catch (9) of the lever (1) for hindering the return motion of this lever thus prolonging the duration of the gearing of the rotary part (3) with the disc (8).

Abstract: Analog display calendar watch having a window or windows and an hour spindle changing device in which the movements of the hour hand and the disc or discs of the calendar are synchronized.The calendar disc is driven once every 24 hours by a rocker lever which supports a plate having a catch engaging the calendar disc, the plate being rotated by a 24-hour wheel and effecting a whole number, greater than one, of turns in 24 hours. The width of the catch is slightly less than the space between two teeth of the calendar disc, so that any forward or backward movement of the hour hand, controlled by the hour setting spindle, permits an immediate forward or backward movement of the calendar disc.