Rotonde de Cartier Astrocalendaire: the perpetual attraction

The design of some watches catches the eye with such intensity that it is impossible to forget about them afterwards. The Rotonde de Cartier Astrocalendaire is undoubtedly among those rare references that have expertly merged creative architecture and an uncommon mechanical layout. It is such a perfect merge that it is difficult to decide which of these two different universes had a greater hand in the production of such a pieces.

Exceptional watchmaking creativity

Led by Carole Forestier Kasapi, the team has the ability and the talent to come up with remarkable creations. The least that can be said about this association of skilled people is that, in only a few years, it has managed to take the Cartier maison to new heights. Indeed, the brand has gone from just producing luxury watches to being one of the most creative producers in all watchmaking sectors, particularly that of great complications.

Of course, we are talking about a brand that is perfectly able to find its own means to achieve its ambitions and that knows to be surrounded by the right people. However, the brand also listens to its designers and developers. Indeed, producing several new high-end creations annually is a true challenge, even for a great maison, and it needs full cooperation from its collaborators. Just like in any other craft, creativity in watchmaking does not just happen. Even for skilled people like Carole Forestier and her team, creating extraordinary timepieces requires constant work and a team to contrast ideas with.

Reinterpretation of the Perpetual Calendar wheels

As highlighted by Carole, the starting point was to take some distance from the traditional display of calendar information. This is actually easy to say but in fact, there are quite a number of pitfalls involved as it often happens that the execution of things that are “possible” is complicated. Carole explains: “To be successful in improving what already exists, it is sometimes necessary to use a whole different approach, even if that means that the complication itself has to be reinvented. When we started, it seemed important to target the weaknesses of existing Perpetual Calendars.

The final objective was to ‘reinvent’ it, to give it a new dimension and aesthetics and to facilitate the production of one of the most appreciated complications in the world”. She adds: “To this end, we decided to only use wheels”. This construction consists of very few springs, cams, levers, snails or stars.

Carole continues by explaining that the reason for this choice is natural and it is related to the problems inherent to chronometry: “The precision of these pieces is usually influenced by calendar information due to the use of springs and cams. The date leaps – particularly ‘cumulated’ leaps, i.e. date, day and month – charge the two barrels with energy, thus causing fluctuations”. As Carole reminds us: “when there are only wheels, there is no element to overcome and fight, which makes this an interesting choice. Even better: if we use a (properly aligned) gear train, we also solve the problems of adjustment and calendar corrections”.

Preventing damage

In a classical construction with corrections that are always badly identified, the biggest problem arises when it is impossible to do anything without the risk of breaking a component. As Carole explains: “With the gear trains, we can make corrections whenever necessary without the risk of breaking anything; it is an enormous advantage”. To make the Rotonde Astrocalendaire perfectly readable, the winding crown placed in an intermediate position adjusts the date and month. The leap year, displayed at the back of the watch through a transparent back,  is also adjusted via the crown. Only the day of the week – with only seven possible options – has an adjusting push-button, embedded at 2 o’clock in the platinum case middle.

A caliber named desire

Its self-winding caliber with flying tourbillon reference 9459 MC consisting of 67 gears is an innovating mechanical construction, which only makes sense when it is associated with a unique display that offers perfect readability. Its design leaves no one indifferent and accentuates circles in this configuration born from the fertile mind of a whole team.

Concentric and overlapping, the circles are all projected on the dial like the ripple effect made from a cobblestone deliberately thrown into a pool of still water. The circles are actually part of the plate that provides the calendar information: the date, month and day. Unlike traditional constructions, the dial’s layout is not flat but rather plays with depth with every concentric circle being carved deeper than the previous one till they reach the top of the flying tourbillon’s frame. Incidentally, the latter has been cleverly housed in the center of this sort of amphitheater dedicated to the calendar.

Purists who appreciate exceptional features will undoubtedly want to see these circles turn to align the affixed calendar information in the 12-6 axis. Let’s not forget, however, that this type of mechanical watch would have typically consumed too much energy from the movement, whose main function should always be to display time as accurately as possible. Therefore, some fine blued apertures have been used to display the calendar information. They are all layered and interdependent and they support the fine (invisible) PVD-treated blue felloe wheels that are associated to their own plate.

The spinning of these toothed circles on the edge, driven by a gear train that is piloted by an organ that centralizes the data, has been partially patented. The demand particularly focused on the wheel with three “flexible” teeth (whose function is to manage the different month length) or more precisely on the fact that three of the teeth are retractable.

The Rotonde de Cartier Astrocalendaire is fascinating, beautiful and perfectly in sync with the brand’s signature. It is a 45-mm platinum watch inspired and created for this very reason, in a limited edition of 100 pieces worldwide. This mechanically complex and original piece, which in terms of display and from a purely stylistic point of view, was assembled and regulated in the new Cartier workshops located at the heart of Calvin’s city. It completely corresponds to the specifications of the rare “Poinçon de Genève” certification, which is affixed on one of its bridges.