Tonda Annual Calendar: Annual and Lunar Calendars on the Same Dial
“The calendar is a man-made system designed to be in balance with the seasons and phases of our planet. The rotation of the Earth around the sun imposes these on us, and we record them with the respect of an enthralled observer. The annual calendar and its moon phase reflect the cosmic order that governs us.”—Michel Parmigiani
Parmigiani Fleurier presents the Tonda Annual Calendar, a piece that conveys Michel Parmigiani’s passion for these complications. In his honour, the manufacture has developed the calibre PF339, which features both a retrograde annual calendar and a precision moon phase. In combination, these two complications ensure the new Tonda Annual Calendar is a piece wholly devoted to astronomy, as it transcribes the rotation of the Earth in relation to both the sun and the moon.
The true beauty of the Retrograde Annual Calendar lies in the fact that the wearer maintains a point of contact with the watch each year. The date is automatically adjusted based on the number of days in the month—30 or 31—but it works on the basis of 29 days for February, whether or not it is a leap year. Therefore, once a year, or rather, three times every four years, at the end of February, the wearer of the Tonda Annual Calendar can remove the watch from his or her wrist and re-establish contact with its subtle mechanism by setting the date manually. It can then be left alone to follow its path flawlessly for the next 365 days. The retrograde date indication never obscures the moon phases at 6 o’clock, showcasing this highly poetic complication. The day of the week and the month are shown in windows at 9 o’clock and 3 o’clock respectively, for perfect legibility.
PRECISION MOON PHASE
The moon phase on the Tonda Annual Calendar is added to the calendar indications. It is known as a “precision moon phase” because it only needs correcting once every 122 years—remarkable accuracy that requires a compensation for the difference between a classic lunar cycle (29 days and 12 hours) and the actual lunar cycle (29 days, 12 hours, 44 minutes and 2.8 seconds). The Tonda Annual Calendar shows two representations of the moon – as viewed from both the northern and southern hemispheres – to meet the needs of wearers in any location. The moon counter and the solid rose gold moon discs stand out on an aventurine glass sky that evokes the poetic beauty of a galaxy full of twinkling stars.
Compared to its predecessor, the Tonda Quator launched in 2011, the Tonda Annual Calendar is notable for its understated character and legibility. The designers have enlarged the bezel to reveal as much of the dial as possible. The minute track and indices sit on the outside, producing a floating effect and guaranteeing highly accurate time reading. The numerals on the retrograde date are arranged on the inside, harmoniously encompassing the day and month counters. The dial is constructed in several levels, and the three-dimensional arrangement of the various counters creates its relief and richness. The hands are slimmer and more elongated than previously, although their proportions are perfectly in line with the golden ratio beloved of Michel Parmigiani. The Tonda Annual Calendar is available in two versions: a rose gold case with a white grained dial – a speciality of the manufacture; a white gold case with a black opaline dial.
THE CALIBRE PF339, DEVELOPED AND MANUFACTURED IN-HOUSE
Using the PF331 automatic movement as a base, Parmigiani Fleurier developed the calibre PF339, equipped with an additional module dedicated to the Retrograde Annual Calendar and its precision moon phase. The unique feature of this automatic movement, with a power reserve of 50 hours, is its series-mounted double barrel. This stabilises the distribution of energy so that it is transmitted to the regulator at a constant level. The movement is ornamented in line with Haute Horlogerie standards, featuring hand-bevelled bridges with Côtes de Genève decoration and an oscillating weight in solid rose gold adorned with a guilloché barley grain motif. The craftsmanship on the Tonda Annual Calendar is exemplary right down to the minutest details—even those that remain hidden.