With the Mechanical Computer at the heart of the QP à Équation Millesimé Edition, Greubal Forsey's newest timepiece brings a revolutionary stance to one of the watchmaking world's oldest complication – the perpetual calendar, by incorporating the equation of time. This was only made possible with the creation of the Mechanical Computer.

The Mechanical Computer – Greubel Forsey's seventh invention – is essentially the urban 25-part component version of some of the calendar functions which were incorporated in age-old astronomical clocks. The new interpretation enables ergonomics and easy readability of the various now-simplified functions of the watch. It also allows all corrections – including days – to be made by rapidly turning the bi-directional crown. The Mechanical Computer directly drives a system of sapphire disks which display the difference between the “real” solar time vis-à-vis the civil time. This difference is called the “equation of time”.

The dial of the QP à Équation offers multiple information which is as easy to set and read as a simple calendar. It indicates the leap years, 24 hours of the day and night, the day of the week, the large date, the month, the hours, the minutes, the seconds, and lastly, the chronometric 72-hour power reserve.

The movement side of the timepiece, on the other hand, displays the equation of time with the months, seasons, solstices, and equinoxes, along with the calendar year.

One of the three patent inventions, the Tourbillon 24 Secondes, provides the timekeeping of the watch. The invention solves the problem of critical positions of the oscillator in relation to gravity by improving the chronometric performance of the system using a rapid revolution of the tourbillon cage and a 25 degree angle.

The new 43.5mm Millésime white gold watch is an ultra-complicated timepiece which offers a simple linear display.